| |
Corps Capital Construction Project Review
The Scientific Basis for Juvenile Fish Passage Improvements in the
Federal Columbia River Power System: John Day Dam Extended Length Turbine
Intake Screens and Bonneville Dams Bypass System Outfalls
June 9, 1998 | document ISAB 98-4
Contents
INDEPENDENT SCIENTIFIC ADVISORY BOARD
851 SW Sixth Avenue, Suite 1100, Portland, OR 97204
Peter A. Bisson, Ph.D.
Charles C. Coutant, Ph.D.
Dan Goodman, Ph.D.
James A. Lichatowich, M.S.
William J. Liss, Ph.D.
Lyman McDonald, Ph.D.
Phillip R. Mundy, Ph.D.
Brian Riddell, Ph.D.
Richard R. Whitney, Ph.D.
Richard N. Williams, Ph.D.
INTRODUCTION
Definition of the Assignment
This report responds to a request for assistance from the Northwest Power
Planning Council (Council) dated January 7, 1998 on issues related to the
planned capital construction projects of the U. S. Army Corps of Engineers
(Corps or COE) (i.e., the Corps? Columbia River Fisheries Mitigation
Program, or CRFM Program).
The U.S. Congress, in its appropriations bill for FY 98 directed the
Council, with assistance from the Independent Scientific Advisory Board (ISAB),
to review the mainstem Columbia River capital construction program of the
Corps. The review is to evaluate the technical need for costly fish passage
strategies at mainstem dams. The Northwest Power Planning Council document
of January 7, 1998, identified sets of general and specific questions that
Council staff initially felt would help focus the review by the ISAB
(Appendix A). Subsequent discussions with the ISAB narrowed the focus at the
outset to near-term and long-term assignments. The three near-term
assignments are:
1. Role of mainstem fish bypass measures in an ecosystem approach for the
Columbia/Snake rivers;
2. Review of the scientific basis for future investment in
extended-length bar screens at John Day Dam;
3. Review of the scientific basis for juvenile fish passage improvements
at Bonneville Dam.
Long term assignments to be completed in December include reviews of the
COE's programs for surface bypass and dissolved gas abatement (tentatively
scheduled for completion in September 1998) and a comparative evaluation of
multiple technologies for aiding downstream passage of salmonids.
The Council established a policy context for the review of the CRFM
Program concerning possible major alternatives for future configuration of
mainstem hydroelectric dams presently under consideration in the region. The
following four future alternative system configuration scenarios provided
sideboards for the review:
1. All existing mainstem dams, including dam modifications, remain in
place and operational for the foreseeable future.
2. All dams remain in place except that the four lower Snake River
projects are breached to provide a natural river condition in the Snake
River within the next 5-10 years.
3. All dams remain in place except that a lower Columbia River project,
such as John Day Dam, is breached or lowered within the next 10 years.
4. Dams remain in place except that the four lower Snake River projects
are breached to provide a natural river condition in the Snake River and
John Day Dam is breached or lowered in the Columbia River within the next
5-10 years.
During 1999, the region will receive additional guidance on operational
scenarios. The National Marine Fisheries Service is scheduled to issue a
longer term Biological Opinion on the operation of the federal Columbia
River hydroelectric system in 1999.
Preparation of the Response
The ISAB used the Council's scoping document (Ruff 1998) as a guide for
its review. Each of the Council's questions was adapted to the specific
circumstances of the project being reviewed. We attempted to provide a
direct answer to each of the Council's question, with an explanation.
Information for the review was derived from a number of sources. The ISAB
received both oral presentations and written documents for its review. The
COE staff briefed the ISAB on January 20 and February 17. Each briefing was
attended by representatives of other organizations in the Columbia River
basin, who also were offered time to provide their views and documents.
Lists of the agencies participating and the documents tendered are available
on request from Erik Merrill at the Council.
The full ISAB initially discussed the scope of the review and the desired
product. A subcommittee of the ISAB reviewed documents and prepared the
initial draft report. The draft was reviewed and modified by other ISAB
members. This final report is a consensus document of the Board.
JOHN DAY EXTENDED-LENGTH SCREENS
The Corps of Engineers proposes to install extended-length submersible
bar screens, ESBS, in the turbine intakes at John Day Dam as a replacement
for the standard-length submersible traveling screens now in place. The
purpose of the proposed operation is to increase the percentage of the
juvenile emigrant salmonids guided into the bypass system for the
powerhouse, thereby decreasing the complementary percentage of the emigrants
passing through the turbines. This is expected to increase the survival of
the emigrants passing John Day Dam based on the theory that emigrants
passing through the bypass have higher survivals than emigrants passing
through the turbines.
Council Questions on John Day Extended Length Screens
1. How does the concept of John Day turbine intake screening fit
within the context of restoration of normative conditions to the Columbia
River ecosystem?
The proposal for installation of the John Day extended length screens
does not accommodate the natural ecological processes and juvenile salmonid
migratory behaviors needed to sustain salmonids in the Columbia River basin,
as explained in reviews such as Upstream (National Research Council
(NRC), 1996) and Return to the River (Independent Scientific Group (ISG),
1996).
Screens at turbine intakes at John Day and elsewhere in the Columbia
River mainstem inherently run counter to the behavioral characteristics of
emigrating of juvenile salmon and steelhead. During periods of active
downstream migration, juvenile salmonids characteristically are concentrated
in the highest velocity regions of a river, which occur in the thalweg and
upper third of the water column. Being drawn into or actively sounding into
deep turbine intakes is not a normal behavior of downstream migrants, with
the result that many fish are delayed at dam forebays. Delay in the forebay
increases risk of mortality for juvenile salmon and steelhead through
predation, exposure to high temperatures and communicable diseases.
One aspect of screening turbine intakes that could be considered
consistent with natural ecological processes and juvenile salmonid migration
behaviors are the location of the screens in the upper portions of the
turbine intakes, and diversion to the gatewells. These aspects take
advantage of the natural tendency of migrating juvenile salmonids to return
to the surface after diving into the turbine intake.
On the other hand, these factors are not likely to apply equally to all
species and populations. Due to inherent differences in size, swimming
abilities and behavioral responses to bar screens, some populations, species
and life history types may experience increases in survival while others may
be harmed. Management actions that favor normal ecological processes and
support of the typical juvenile salmonid migratory behaviors, such as
surface spill and surface bypass, may provide benefits to a broader variety
of populations, species and life history types than do remedies such as
turbine intake screens.
2. What is the record of effectiveness of John Day turbine intake
screening to mitigate for the mortality that would otherwise be inflicted by
mainstem hydroelectric dams, and how would the implementation of extended
length screens contribute to improving this record? Please address the
following specifics in answering this question: a. How has John Day turbine
intake screening contributed toward meeting salmon recovery goals? b. What
are the positive impacts of John Day turbine intake screening facilities? c.
What negative impacts have the facilities incurred?
Definition of terms: Fish guiding efficiency, FGE,
is the proportion or percentage of juvenile salmon entering the turbine
intakes that are diverted into the bypass system. Fish passage efficiency,
FPE, is the proportion or percentage of juvenile salmon passing the
hydroelectric project by routes other than turbines. When all of the river's
flow is going into the powerhouse there is no spill, and the FGE is equal to
the FPE. At times when not all of the river's flow is entering the
powerhouse, FGE is less than FPE. Neither FGE nor FPE taken alone is a
measure of survival experienced by juvenile salmon or other emigrants during
hydroelectric project passage. Hydroelectric project survival is the
proportion or percentage of the juveniles that pass the dam alive during a
specified time interval, such as the migration season. The term, "nominal",
is given to a numerical survival value when it is applied to a route of
passage at a hydroelectric project other than the project at which the
survival was actually estimated empirically.
The record of effectiveness of turbine intake screens is uncertain. Large
incremental improvements in FGE have been steadily made over the last 20
years at the mainstem dams operated by the COE, as well as at dams operated
by other parties. For example, during the 17 years of service at John Day
Dam, before standard traveling screens were installed, COE staff estimated
that only 2% of juveniles entering the turbine intakes exited via orifices
into the "gatewell salvage systems". When standard screens were installed in
1985, FPE for wild yearling chinook improved to about 64% (Table 4 in
Anderson et al., 1998). [Note that in the absence of spill at John Day, FGE
is equal to FPE]. Similar fish passage efficiency improvements were also
realized at other projects during the 1980s when turbine screens were
installed. Despite these dramatic improvements in fish passage efficiency,
no corresponding improvement in the return rates of wild adult stream type
salmon and steelhead above Bonneville Dam has occurred and the downward
trend in salmon abundance has continued (National Research Council, 1996;
Whitney et al. 1997). Either survival in passing dams was not improved or
the improvement was masked by changes in survival elsewhere (often suggested
to occur in the estuary or ocean).
The interim objective in both the Fish and Wildlife Program of the
Northwest Power Planing Council (FWP) and National Marine Fishery Services?
(NMFS) Proposed Recovery Plan is 80% FPE and 95% survival of juveniles past
each project (i.e., 95% project survival). The COE expected with the
installation of extended-length submersible bar screens (ESBS), to achieve
55%-84% improvement of FGE or 3% project survival improvement for spring
migrants and 20-60% improvement of FGE or 4% project survival improvement
for summer migrants (IT Briefing Summary). These improvements, if actually
achieved, would contribute to the goal of 95% project survival. Installation
of ESBS was estimated to increase FGE relative to standard length
submersible bar screens (SBS) for yearling spring chinook (58% to 84%),
steelhead (86% to 94%), sockeye (41% to 79%), and subyearling chinook (32%
to 60%) (Fredericks and Graves memo to Hydro Files, April 9, 1997; Brege et
al., 1997; Krcma et al., 1986; Brege et al., 1992; Whitney et al. 1997).
Interpretation of the record of effectiveness of John Day turbine intake
screening to mitigate for the mortality that would otherwise be inflicted by
turbine passage would depend on how many of the juveniles were passed by the
primary non-turbine alternative route, spill. Spill can occur during the
migration season either involuntarily when river discharge exceeds the
turbine capacity of the dam or voluntarily when spill is used as a
management tool to pass juveniles. To evaluate the effectiveness of ESBS,
the ISAB sought to verify expected improvements under operational scenarios
that included or excluded passage of juvenile salmon by spill. Our efforts
to match calculations of effectiveness of ESBS by the Corps and NMFS have
highlighted many uncertainties, which are discussed in the answer to
Question 3 below. Our calculations suggest that 80% FPE possibly could be
achieved with ESBS for yearling chinook, steelhead, and perhaps for sockeye,
but probably not for ocean type chinook over the course of an entire annual
migratory season. The ISAB calculated that, assuming no juveniles are passed
by spill, the reduction in nominal total project mortality of yearling
chinook with extended-length screens relative to the standard screens might
be 3.1%. The calculation used average numbers that were provided in agency
documents for FGE of both screens, mortality in turbines, and mortality in
the bypass systems (principally the Fredericks and Graves memo, Anderson et
al., 1998, and summaries in Whitney et al., 1997). Reduction in mortality of
subyearling chinook with the new screens relative to the standard screens
was taken to be 3.0%. These figures are comparable to those of the COE.
Spill decreases the relative improvement in survival of juvenile salmon
due to the ESBS. For example, ISAB calculations suggest that when fifty
percent or more of the emigrants are spilled, the difference in nominal
survivals between standard and extended-length screens is 1.5% or less. A
question for fisheries managers is whether there is a greater increase in
survival by voluntarily spilling water or by minimizing spill and depending
on screens and fish bypasses to protect fish from turbines.
However, the more important question is whether a putative improvement in
project survival of a few percent following installation of extended-length
screens will contribute in a meaningful way to recovery of stocks at risk of
extinction or to protection of healthy stocks. The answer to this question
needs to be weighed relative to the costs of the installation and the
alternative costs of lost power generation if survival is managed by
voluntary spill. Analysis that addresses this question quantitatively and
currently is not available. The analysis will require thoughtful
collaboration between biologists and economists.
When considering species other than juvenile salmon and steelhead, the
application of ESBS is indeed uncertain. Any changes in the FPEs generated
by addition of the ESBS for other anadromous species, such as Pacific
lamprey, and other migratory species, such as the catostomids, are unknown.
Impingement of juvenile Pacific lamprey has been demonstrated for the John
Day ESBS, but the proportion of migrants affected is not known.
3. What are the major uncertainties or research questions associated
with increasing the ability of John Day turbine intake screens to divert
juvenile emigrants to the bypass system?
a. The 80% fish passage goal and the 95% survival goal at each
hydroelectric project are policy decisions. It is uncertain how these goals
might relate to an expected improvement in the relationship between the
numbers of downstream migrants and numbers of returning adults.
b. A major uncertainty regarding the effectiveness of turbine-intake
screens (both conventional and extended-length) is highlighted by the fact
that dramatic improvements in FGE over the last 20+ years at most Columbia
basin mainstem dams have not been matched by dramatic improvements in
returns of adult salmon and steelhead to spawning grounds above Bonneville
Dam. In addition, there is no documented evidence that installation of
screens has slowed the decline of salmonid stocks. However, documentation of
improvements in numbers of returning adults is complicated by the difficulty
of separating the mortality that occurs during dam passage from the
mortalities experienced in other parts of the life cycle (especially in the
estuary and ocean). Furthermore, evaluations of smolt to adult survival in
Columbia River salmon generally lack statistical power sufficient to have a
reasonable chance of detecting the effects of small, incremental increases
in downstream survival of juveniles at a project such as John Day Dam.
c. The following uncertainties involve the estimation of FPE and project
survival. These uncertainties render estimates of FPE and project survival
at John Day Dam problematic.
? There is an uncertainty with respect to the number used for downward
adjustment of the estimates of FGE for standard screens. In calculating
project survival, a downward adjustment of 20% in measured FGEs for screens
in the Snake and lower Columbia rivers was made, due to the location of the
fyke net array directly below the screens. The fyke array is thought to have
pushed more water and fish upward than would have occurred in its absence
(Anderson et al., 1998). The basis for this adjustment is tenuous. If the
unadjusted FGE number is used, the expected improvement in survival due to
installation of ESBS is lowered. For example, if the unadjusted FGE figure
for yearling chinook is used (69%, Anderson et al., 1998), the estimated
total mortality would be 5.4%, giving a 1.6% improvement in survival with
extended screens, compared to the 3.1% improvement estimated with the
adjustment.
? The estimate of bypass mortality (2%) used in calculating project
survival may be too conservative. Bypass survival studies have not been
conducted at John Day Dam. Numerous uncertainties are associated with bypass
survival studies at other dams, which influence their applicability to John
Day. Furthermore, NMFS studies at Snake River dams indicate that bypass
mortality can be highly variable (0.6-7%; Bill Muir, NMFS, personal
communication). Analysis of the sensitivity of project survival to variation
in bypass mortality was not available, but it is likely that small changes
in bypass mortality could lead to large changes in benefits ascribed to ESBS.
? Recent empirical studies of project survival of species and life
history types at John Day Dam for standard length screens are lacking. Thus,
project survival for standard-length bypass screens at John Day must be
extrapolated from other sources or earlier studies for determination of
expected improvement in survival with ESBS. The use of actual estimates of
survival is preferred over the use of nominal figures.
? Estimation of improvement in project survival is complicated by
difficulties in selecting the appropriate FGEs from among those that have
been measured (Anderson et al. 1998; Fredericks and Graves memo to Hydro
Files April 9, 1997; Whitney et al., 1997). Moreover, the use of average
FGEs in determining project survival may bias survival estimates. Measured
FGEs vary not only among species and life history types, but also with time
of year, degree of smoltification, time of day, and other factors. (Whitney
et al 1997). Analysis of the sensitivity of project survival estimates to
variation in FGE was not available.
? Detecting effectiveness of small increases in downstream survival of
juveniles at John Day on adult returns will be difficult. Rigorous modeling
studies were not available to assess the probability of detecting effects of
small increases in survival at John Day Dam on smolt to adult return rates (SARs),
given variability in survival due to fluctuations in freshwater and ocean
conditions.
d. Increased gatewell turbulence is a consequence of extended-length
screens. During orifice blockages, fish in the gatewell cannot exit as
intended and smolts would be subjected to increased turbulence for extended
periods of time. The actual effects on salmon and other species of prolonged
exposure to these higher levels of turbulence have not been measured,
however the effects are likely to be harmful. Even in the absence of orifice
blockages, turbulence may lead to higher levels of descaling than current
designs of standard screens. Knowledge of the effects on survival of
juvenile salmon and other species of prolonged exposure to high turbulence,
and the effects of descaling on survival of juvenile salmon are
uncertainties relevant to understanding the effects of extended length
screens at John Day Dam.
e. There are uncertainties of the effects on fish of increased debris
loads in the bypass systems. An unintended consequence of extended screens
is their ability to guide more debris into gatewells where it then travels
into the bypass system. Although there are programs to check and clean
orifices at each project, much of the increased debris goes into bypass
systems. Bypass systems have not been specifically designed to minimize the
effects of increased debris load on juvenile emigrant salmonids. John Day
Dam has an open flume system that makes handling of debris problems easier,
nonetheless experience in coping with debris from extended length screens is
limited. Debris in dams can pose a serious mortality problem for juvenile
emigrant salmonids (Matthews 1992).
f. There are uncertainties in the development of the engineering
criteria. Options for engineering features include angle of deployment of
the screen, porosities of backing plates, configurations of vertical barrier
screens, location and diameter of orifices, and numerous other features of a
complete bypass system. Prototype tests are designed to help select the best
combination for the particular project, but these are not necessarily the
final features of the full system, as evaluation continues once it is in
place.
g. The following uncertainties are associated with the spill alternative
(necessary for a comparative evaluation of ESBS):
? The mix of species included in spill is not known. This is important
for measuring the true effects of using spill as a supplement to the FGE of
intake screens for achieving the 80% fish passage goal.
? Spill passage efficiency curves (percentage of emigrants passed as a
function of percentage of river flow spilled) are not available for John Day
Dam. Because we do not have the spill passage efficiency curve, it is not
possible to evaluate the feasibility of passing a particular percentage of
emigrants under the operational scenarios posed by the Council. The
assumption of a 1:1 relation between proportion of flow spilled and the
proportion of the emigrants passed via spill is unlikely to be universally
valid at all spill levels (Whitney et al. 1997). Relating levels of spill
with levels of adult returns, and smolt to adult survivals will be
difficult, just as it has been with evaluation of the effectiveness of
bypass systems.
4. How does the existing level of scientific uncertainty affect the
use and management of John Day turbine intake screening?
Scientific uncertainty about the effect of the turbine intake screening
on the recovery of salmon populations makes use and management of the John
Day turbine intake screens difficult to objectively evaluate in terms of
long-term population viability. The use of turbine intake screening at John
Day needs to be approached with substantial caution in view of the
uncertainty.
5. How does the existing level of scientific uncertainty affect the
question of whether or not to proceed with increasing the ability of John
Day turbine intake screening to facilitate entrainment of juvenile emigrants
to the bypass system?
The small nominal increase in survival from installation of ESBS and the
existing level of scientific uncertainty concerning the actual magnitude of
the nominal increase make it difficult to justify proceeding with
installation of ESBS at John Day dam at any cost. The high cost of ESBS
makes justification even more dubious, but must be tempered by costs of
spill as an alternative. Economic uncertainty (beyond the scope of the ISAB
review) needs to be considered.
6. What is the relative likelihood that increasing the ability of
John Day turbine intake screening to facilitate diversion of juvenile
emigrants to the bypass system will contribute to achievement of the goals
of the NMFS Biological Opinion, the Council's Fish And Wildlife Program, or
the tribes' 1995 Anadromous Fish Restoration Plan, Wy-Kan-Ush-Mi Wa-Kish-Wit
? Spirit of the Salmon?
There are a number of goals that could be identified in the three
documents referenced. We highlight three of them for our purposes here, the
80% fish passage and 95% survival goal (which are related), an increase in
numbers of adult salmon or recovery (which in theory is related to the
preceding two), and maintenance of diversity of the salmon stocks.
a) FPE and project survival goals may not be met for some species and
life history types. The 80% FPE goal probably would be achieved by ESBS for
yearling chinook, steelhead and coho, and perhaps for sockeye, but it would
not be achieved for subyearling chinook. It is difficult to discern whether
any increases in project survival would result in increased adult returns.
b) Biodiversity may not be protected. Ample evidence is available to
demonstrate that the collection efficiency of each bypass system varies by
species, life history type and population. The FPE goal, if implemented over
the long term, could increase survival of some stocks/life histories that
pass through the existing system at an optimal time, while the survival of
other stocks/life history types that pass through the system at other times
could be unaffected or adversely affected. The FPE goal should reflect the
need to achieve high passage efficiency and survival for all stocks and/or
species throughout the entire seasonal migration period. Each of the
individual stocks must pass through the selective mortality bottleneck
imposed by the mainstem dams. There is a critical clash between the
upper-river salmon restoration programs and Corps mainstem passage programs.
Upper river programs, such as many ESA-driven actions, employ performance
criteria focused on individual stocks or spawning populations, while the
Corps uses a seasonal average FPE criterion that ignores biodiversity at the
stock level. Nearly all evidence for the effectiveness of turbine intake
screens has been presented as composite numbers that average across the
migration season, for a species (i.e. steelhead) or a life history type of a
species (i.e. yearling chinook). These averages are insufficient for
ensuring that changes in downstream survival (if detected) would preserve
biodiversity.
7. What scientific information is available to compare the John Day
fish passage strategies, standard length turbine intake screens versus
extended length screens?
a. Are there significant limitations in the scientific
information used to evaluate the different John Day turbine intake fish
passage strategies? If so, how can the region best fill these information
gaps?
The following are significant limitations in scientific information used
to evaluate the different John Day turbine intake fish passage strategies.
Please refer also to the uncertainties discussed above.
? There is a substantial likelihood that the screening and bypass system
selectively favors some life history types/populations/species over others.
A constant (average) FGE for each species/life history type was used to
estimate seasonal FPE and project survival. FGE can vary with time of year,
degree of smoltification, time of day, and other factors that would cause
differences in project survival of individual populations emigrating at
different times of the year (Whitney et al. 1997).
? We lack rigorous modeling of juvenile survival at a project level. We
also lack modeling of the overall life cycle survival. Inferences from these
modeling efforts are essential to support the decision to install ESBS. It
would have been useful to see model projections pertaining to the
sensitivity of juvenile survival at a project as well as life cycle
survival. These models should address variability in important factors such
as in FGE and bypass mortality. Such models, although imperfect, are
available for comparative analyses.
? The use of nominal survival figures creates substantial uncertainty.
The nominal increase in juvenile survival through John Day Dam following
installation of ESBS is an extrapolation from experience in other
localities. Each hydroelectric project is different, hence the concern that
experience in other localities does not necessarily apply to John Day. The
lack of empirical data pertaining to survival of juveniles at John Day to
support installation of ESBS, the uncertainties of bypass survival studies,
and potential variability of bypass mortality all lead us to seriously
question the magnitudes of the projected benefits of John Day ESBS.
Detecting effectiveness of small increases in survival and the lack of data
make it difficult to undertake rigorous modeling studies that assess the
resulting influence on smolt to adult return rates. This problem is
exacerbated by the relatively large variability in survival due to
fluctuations in freshwater and ocean conditions. In short, estimated
increases in project-specific survival are so small that even if they occur
we may never be able to evaluate their effects on adult returns. Given that
we presently have no estimates that apportion adult returns to the effects
of turbine intake screens at any single hydroelectric project, it is
unlikely that estimates of the cumulative effects of ESBS installed over
multiple projects on smolt to adult return rates will be forthcoming.
? We lack empirically demonstrated benefits in SARs from installation of
standard length screens, or analytical evidence that installation of screens
has slowed decline of some salmon stocks.
? The lack of rigorous comparison (via modeling or other studies) of
alternative scenarios to extended length screens such as improved spill
efficiency and surface bypass, for achievement of not only 80% FPE and 95%
survival but also significantly greater SARs, is a significant limitation in
scientific information.
b. Within the constraints of the four operational scenarios provided
by the Council, is the effectiveness of John Day standard length turbine
intake screens adequate to achieve the interim performance objective of 80%
fish passage efficiency and 95% juvenile fish survival at each dam
Under all scenarios, we believe that, with the existing levels of
uncertainties, there is inadequate scientific justification to conclude that
the objectives will be achieved.
c. Does the proposed implementation of extended length turbine intake
screens at John Day Dam have a high probability of achieving the expected
biological benefit (salmon survival improvement) without undue risk to other
anadromous and/or resident fish populations?
The ESBS likely will favor some species, life history types, and stocks
over others and could be detrimental to some species such as Pacific
lamprey. The extent of the effects on different stocks is unknown.
d. Does the proposed implementation of extended length turbine intake
screens at John Day Dam provide potentially interim (within the next 10
years) biological benefits, or is it consistent with longer-term
increasingly normative system configuration strategies?
Improvements in FGE of turbine intake screening are not consistent with
longer-term increasingly normative system configuration strategies. Existing
turbine intake screening may be used in conjunction with a program to
implement normative strategies. However the search for effective means of
improving survival of the full diversity of salmon and steelhead populations
needs to be expanded.
John Day Conclusions
The incremental approach to salmon restoration embodied in the John Day
Dam extended length bypass screen program involves activities that (1) rely
on expensive technology and (2) focus on very narrow segments of the life
history of the species/population, without linking the segments to the
entire life cycle. Incremental approaches often are fragmentary and lack a
unifying conceptual foundation and a context in a well-defined restoration
strategy. Each incremental activity is acknowledged to bring about only a
small increase in survival but the cumulative increase in survival from all
incremental activities is assumed to lead to significant survival advantages
for the target species. Reliance on small-scale incremental approaches stems
in part from reluctance to make larger-scale, longer-term changes that could
have a higher probability of measurable success. Extended-length screens are
an incremental technology that provides improvement in average, seasonal FGE
over standard screens at diverting migrants from the turbine intake.
However, there is uncertainty over whether increased FGE, if achieved, will
translate into increased measurable project survival and increased adult
returns.
John Day Recommendation:
Implementation of the COE program to install extended-length screens at
John Day Dam does not appear to be justified. Instead, the ISAB recommends
pursuing existing surface spill alternatives and funding research toward
possible deployment of a surface-flow bypass system. Where conventional or
extended-length screens are already deployed, integrate their continued use
with future installations of new facilities designed to mimic natural
processes. Mitigation measures need to improve survival of the full range of
diversity in salmon and steelhead populations, while taking into account
impacts on other species. We are aware that with the existing screens spill
is required in order to supplement the FGE of the screens and move toward
the 80% fish passage goal. We are also aware that gas supersaturation
restricts the amount of spill so that the 80% goal can not be achieved (Fish
Passage Center, 1994; Whitney et al., 1997). Nonetheless we are recommending
that strategies other than extended length screens that offer to achieve the
80% goal within gas supersaturation guidelines be pursued.
BONNEVILLE FISH-BYPASS OUTFALL RELOCATION
The COE proposes to relocate outfalls of the bypass systems at both
powerhouses in order to move bypassed juvenile salmonids away from known
concentrations of predators. In addition to relocation of the outfall for
the juvenile bypass system, planned alterations scheduled at Bonneville Dam
to the juvenile fish passage facilities include increasing FGE of intake
screens at both powerhouses, replacing the existing bypass conduits at the
powerhouses, joining the two conduits to a common outfall, investigating
surface bypass, and implementing gas abatement strategies (COE briefing to
the ISAB). The ISAB has focused its work in this report primarily on
evaluating the proposed bypass outfall relocation. However, the concerns
expressed over the future of mechanical bypass in the portion of this report
dealing with John Day extended length screens also apply to Bonneville.
Council Questions on Bonneville Hydroelectric
Projects Bypass Outfall Relocation
1. How does the concept of Bonneville outfall relocation fit within
the context of restoration of normative conditions to the Columbia River
ecosystem?
The existing bypass outfalls artificially concentrate the juveniles and
deliver them to locations where they are highly vulnerable to predation.
Concentration of the juveniles into a relatively small volume of relatively
slow moving water at a hazardous location is not preferable to alternative
means of passage designed to recognize and take into account the natural
ecological processes and migratory behaviors needed to sustain salmonids in
the Columbia River basin, as explained in reviews such as Upstream
(NRC, 1996) and Return to the River (ISG, 1996). Avenues of passage,
such as spill, more closely mimic natural situations and processes that
emigrating juvenile salmonids encountered in their evolutionary history.
Consequently, such means of passage should be less selective over the entire
range of stocks and life history types than foreign or unnatural passage
routes. Identifying and implementing more natural passage routes would
increase normative conditions at Bonneville and should result in a decrease
in juvenile mortalities. (See also the response to Question 1, John Day
extended length screens.)
Outfalls are an integral part of bypass systems. The access of emigrants
to these bypass systems differs among populations, species, and life history
type, artificially altering the individual fitness of emigrants, and
ultimately the fitness of populations that comprise the total annual
emigration. This is particularly true for later and smaller emigrants that
are more vulnerable to predation than are the earlier, larger emigrants. For
the long-term, additional and more substantial commitments to normative
conditions, such as may be possible with surface bypass collection and spill
(with reduced gas concentration), are expected to be required for further
improvement of survival of juvenile salmon and steelhead. To the extent that
bypass relocation can reduce mortalities for those juvenile salmon and
steelhead that may enter the powerhouses, outfall relocation would be
supportive of recovery of endangered salmon stocks, and it should reduce
artificial selection against later and smaller emigrants. Relief from the
present situation, where high outfall mortalities are known to be occurring,
through relocation of the combined bypass outfall to deeper, swifter water
more typical of the riverine migration pathway would contribute to
restoration of normative conditions, at least in the short-term. Although
Bonneville outfall relocation should help reduce artificial selection
against later and smaller emigrants, relocation is not supportive of
restoring normative conditions to the extent that the turbine-intake
screening and bypass systems, including outfalls, continue to concentrate
the juveniles. As a longer term consideration, any advantage of relocation
of the outfall might be expected to decrease with time as the current type
of predator alters its behaviors in response to relocation of the prey, or
as other types of predators are able to take advantage of the concentrated
prey.
2. What is the record of effectiveness of Bonneville bypass outfalls
to mitigate for the mortality that would otherwise be inflicted, and how
would the relocation of the outfalls contribute to improving this record?
Apparent survival rates of subyearling chinook salmon passing through
either bypass systems were about the same, or lower, than those of fish
passing through turbines of either powerhouse. Ledgerwood et al. (1994)
evaluated survival through the bypass system and turbine at the first
powerhouse. Survival was lowest through the bypass system, followed by the
turbine, and downstream release. Petersen et al. (1993) documented that
predatory cyprinid fish (Ptychocheilus oregonensis), commonly
known as northern squawfish, are abundant near shore in the tailrace
at the first powerhouse, and that fish of this species on both sides of the
river actively fed on juvenile salmonids that were released at the present
bypass outfall. [Note: Some Native Americans find the standardized common
name for this predator published by the American Fisheries Society (Robins
et al. 1980) to be offensive (Keith Hatch, Columbia River Inter-Tribal Fish
Commission, personal communication). Given the current dispute over the
standardized common name, we chose to use only the generally accepted form
of the binomial, P. oregonensis, to refer to this species.]
There have been numerous studies of mortality rates of juvenile salmon (subyearling
chinook) in and below the bypass system at the second powerhouse (Dawley et
al., 1988; 1989; 1996; Ledgerwood et al., 1990; 1991; Gilbreath et al.,
1993; summarized by Whitney et al., 1997). For two experimental lots of
subyearling chinook, one passing through the turbines and the other through
the bypass, downstream recovery rates of turbine fish were similar to, or
slightly higher than, those of the bypassed fish. Recovery rates of
subyearlings passing via spill were higher than those for subyearlings
passing by either turbine or bypass. Excessive delay of fish in the bypass
system has been documented, although these studies did not find exhaustion
to be a factor in the delay. The excessive delay may have been due to the
use of fish taken directly from a hatchery (unsmolted) for the evaluations.
A summary of the results from 1987 - 1990 provided by Gilbreath et al.
(1993) can be used to estimate mortality in the tailrace below the outfall
as 6.8%. Note that Gilbreath et al. (1993) made this estimate by comparing
the recoveries of an experimental lot of bypassed juveniles to those of a
downstream release (Whitney et al., 1997). Ledgerwood et al., (1994)
reported that at the second powerhouse there appeared to be back eddies or
shore areas where predator numbers concentrate.
At the first powerhouse, the present bypass outfall is located in
the tailrace near the north shore in low velocity water where P.
oregonensis are concentrated. At the second powerhouse, the present
bypass outfall is located in mid-channel, in the type of location advised by
Shively et al., (1996), however, the support structure for the outfall
itself provides refuge for P. oregonensis that can dart out to take
juveniles in passing. In addition, the outfall is below the surface,
requiring that the conduit be pressurized. Current criteria for conduits
require open, non-pressurized systems (NMFS/NOAA 1994 - Appendix D).
a. How have Bonneville bypass outfalls contributed
toward meeting salmon recovery goals?
So far, the existing outfalls appear to have negated whatever benefits
may have accrued to subyearling emigrants from the bypass system because of
high mortalities experienced at and below the outfalls. Contributions toward
other salmon emigrants? recovery is unknown, but it is probably reasonable
to conclude that whatever benefits may have accrued from the bypass system
are probably negated for emigrants of size equal to or smaller than
subyearling chinook with somewhat similar timing. For larger, earlier
emigrants, such as spring chinook and steelhead, the negative effects of the
outfalls could have been less than that observed for subyearling emigrants.
The new location for a combined outfall should decrease predation, based on
environmental characteristics of the site and experimental characterization
of P. oregonensis predation (several studies by the USGS/BRD, Cook,
Washington).
b. What are the positive impacts of Bonneville bypass
outfalls?
There are no positive impacts of existing Bonneville bypass outfall
locations for emigrants of size equal to or smaller than subyearling
chinook with somewhat similar timing, and the expected benefits of the
bypass for other species and life history types are highly uncertain.
c. What negative impacts have the facilities incurred?
Total rates of mortality for subyearling chinook emigrants passing
through the bypass system (including mortality at and immediately below the
current bypass outfalls) is comparable to that experienced with passage
through the turbines. For larger, earlier emigrants, even if the outfalls
are not a negative factor, the fish passage efficiencies at Bonneville Dam
have been historically poor.
3. What are the major uncertainties or research questions associated
with increasing the ability of Bonneville bypass outfalls to facilitate
survival of juvenile emigrants?
There are uncertainties with the potential adverse effects on juvenile
salmonids of transit through a flume that would be about 1.7 miles long (CRITFC
submission at the ISAB briefing), including uncertainties with respect to
stress and physical injury that might be added during transit. The adverse
impacts, if any, of the pipeline will be added to those of the existing
screen guidance systems (CRITFC, 1998).
As for effects of the release location on predation, information
indicates that though juveniles will be released in higher velocity river
flow, they will be more concentrated and some of them simply may swim to
lower velocity shoreline water to recover from stress associated with the
bypass, and predators may follow (Oregon State University telemetry studies
cited in CRITFC, 1988). On the other hand, the juvenile salmon exiting the
re-located outfall are expected to have more time to re-orient and recover
before encountering predators near shore than at the present outfalls. There
is additional uncertainty with respect to the length of time positive
effects may exist, because it is possible that existing types of predators
may alter behavior in response to changing prey density, and other types of
predators may be attracted to the new outfalls.
Although an attempt has been made to consider all features of the new
outfall that would reduce predation on the juveniles that exit, please note
that their effectiveness cannot be predicted with certainty. Post
construction evaluations will be required as uncertainty and unanticipated
results are common factors to be considered and evaluated in the
implementation of new technologies.
4. How does the existing level of scientific uncertainty affect the
use and management of the Bonneville bypass outfalls?
For subyearling chinook, the bypass system cannot be trusted as a
mitigation measure at present due to the nature of the outfall problem (Ledgerwood
et al., 1991; Dawley et al., 1992; Gilbreath et al., 1993; Ledgerwood et al.
1994; Dawley et al. 1996). Demonstration of benefits is necessary because
outfall relocation may not work as intended. Uncertainties also exist for
other stocks and species. The use of mechanical bypass at Bonneville Dam
needs to be approached with substantial caution in view of the uncertainty
regarding the effect of outfall location on survival of emigrants that pass
through it.
5. How does the existing level of scientific uncertainty affect the
question of whether or not to proceed with increasing the ability of
Bonneville bypass outfalls to facilitate survival of juvenile emigrants?
There is no doubt that the present bypass locations cause artificially
elevated levels of mortality (Ledgerwood et al., 1991; Dawley et al., 1992;
Gilbreath et al., 1993; Ledgerwood et al. 1994; Dawley et al. 1996). The
need for relief is certain. The degree to which salmon and steelhead are
dependent on the bypass for improved survival is a matter of decisions about
developing proposed alternative passage routes for fish. None of the passage
routes except intake screens and spill have been shown to be feasible at
this time. Surface bypass systems are under development elsewhere in the
basin for possible general deployment, but would probably still require a
bypass outfall. We presume that the proposed outfall would be used if
surface collection replaces or augments screening of turbine intakes at
Bonneville.
Increased efficiency of turbines might improve the rate of survival of
juvenile salmon passing through the powerhouse (Whitney et al., 1997). As is
the case with outfall relocation, changes in turbine efficiency as they
relate to decreased juvenile salmonid mortality would require a number of
years to implement, evaluate and fine tune. The potential benefits of
increased turbine efficiencies would depend on the size of the emigrant, to
name one key stock- and life history-specific variable.
6. What is the relative likelihood that increasing the ability of
Bonneville bypass outfalls to facilitate survival of juvenile emigrants will
contribute to achievement of the goals of the NMFS Biological Opinion, the
Council's Fish And Wildlife Program, or the tribes? 1995 Anadromous Fish
Restoration Plan, Wy-Kan-Ush-Mi Wa-Kish-Wit ? Spirit of the Salmon?
There are a number of goals that could be identified in the three
documents referenced. We highlight three of them for our purposes here, the
80% fish passage and 95% survival goal (which are related), an increase in
numbers of adult salmon or recovery (which are also related), and
maintenance of diversity of the salmon stocks.
Passage Goal.
The 80% fish passage goal of the three entities (Council, NMFS and
Tribes) can not be achieved at Bonneville Dam with the existing bypass
systems (Whitney et al., 1997). The existing intake screens have been judged
to be unsatisfactory in performance. The FGE for screens at the first
powerhouse is thought to be 38% for fish migrating in the spring (Anderson
et al., 1998) and 10% in summer (Fredericks memo), while at the second
powerhouse, FGE is thought to be 44% in spring (Anderson et al., 1997) and
40% in summer (Fredericks memo).
The existing dam configuration does not permit spill to be provided in
amounts sufficient to achieve the goals, because of limits on the amount of
gas supersaturation and negative effects on upstream passage of adults
created by spill. Other measures, such as surface bypass, have yet to be
demonstrated effective in achieving fish passage around the turbines
(Whitney et al., 1997), but relatively little effort has gone into
development of alternatives to date. Improvements in the intake screen
systems called for by NMFS and the Council will be counterproductive without
modifications of the outfalls to reduce predation, because the expected
result would simply be more fish released into the areas of high predation
with mortality rates comparable to those that occur in passing through
turbines.
Survival Goal.
As a rule, the 95% survival goal is expected to be achieved if the 80%
passage goal is achieved (Whitney et al., 1997). This assumes no
extraordinary mortalities are associated with bypass passage, as has been
the case at Bonneville Dam. Simultaneous efforts are underway to explore
alternative measures for improving survival of juvenile salmon at Bonneville
Dam. All but spill are in the developmental stages, and while they have the
potential for improving fish passage and survival, their actual
effectiveness is unknown at this time. An integrated plan for fish passage
at Bonneville is needed that goes beyond piecemeal additions to technology
such as relocating the outfall, even though that incremental improvement
appears valuable.
Other measures that might improve survival at the project are as follows:
Spill.
At present, in order to meet the 80% fish passage and 95% survival goal,
spill is provided to supplement the FGE of the turbine intake screens. In
practice, the 80% fish passage goal can not be achieved at Bonneville Dam
because of the need to limit spill amounts below those that would lead to
excess levels of gas saturation (Whitney et al., 1997). In 1995, as an
example, only 55% to 62% of the fish were estimated to have passed at
Bonneville Dam through combinations of spill and the turbine intake bypass
system (Fish Passage Center, 1995; Whitney et al., 1997). The remainder
passed through the turbines. Mortality in turbines at the first powerhouse
was estimated to range from 11 to 15% by Holmes (in Whitney et al., 1997),
and about 4% by Weber (1954) and 2 to 3% by Ledgerwood (1993). Holmes
estimates may have been high since some releases were made in the forebay
instead of directly into the turbine (Iwamoto and Williams 1993).
Simultaneous efforts are underway by the COE to develop engineering
solutions at the spillway and tailrace that should make possible release of
larger volumes of spill without producing gas supersaturation that now
limits the amount of spill. For evaluating potential benefits of these
options, the COE has developed some preliminary projections of improvements
in survival that might be achieved at the project. Until tests are
conducted, these must be regarded as speculations. (Bonneville Fish Passage,
Presentation Team to ISAB, February 17, 1998). Under most flow conditions,
it is unlikely, even with these modifications that spill alone could be
provided in sufficient amounts to achieve the 80% or 95% goals without
substantially exceeding gas supersaturation limits.
Improved spill effectiveness.
Spill effectiveness is assumed to be represented by the ratio 1:1 at
Bonneville Dam (J. Ferguson, COE, briefing to ISAB), i.e. the percentage of
river flow that is spill is equal to the percentage of fish that are passed
in spill. Spill effectiveness has been improved at projects where it has
been tried, either by modifying spill to draw water from nearer the surface,
or by spreading the same volume over a 24 hour period (Whitney et al.,
1997). There are no direct measurements of spill effectiveness at Bonneville
Dam, however, the 1:1 ratio is unlikely to be realized at all spill levels
(Whitney et al., 1997).
Extended-length Screens at Bonneville Dam.
The COE began testing a prototype extended-length screen at Bonneville
Dam in April 1998 (John Ferguson personal communication). The proposed
Recovery Plan calls for installation of a prototype extended-length screen
at the second powerhouse in 1999. Any estimate of possible improvement in
FGE for juvenile salmonids that might result from installation of
extended-length screens would have to wait for results of prototype tests.
The poor performance of standard screens at the second powerhouse, installed
without prototype tests, underscores this conclusion. Forecasting survival
benefits resulting from increased FGE would be purely speculative and
unwarranted, given past problems with bypass systems at Bonneville.
Development of a Surface Bypass System
Development of a surface bypass is called for by the Biological Opinion.
The COE has ongoing feasibility studies, that have included model studies,
and there are plans for a prototype test in 1998 (SCT Measures Work Sheet,
17 Dec 97).
Predator control
With predators acting as a major source of mortality for juvenile
emigrants (Riemann et al. 1991), changes in predator abundance and
distribution through control efforts and changes in system operations have
the capacity to influence the efficacy of all mainstem passage measures,
including ESBS and bypass outfall relocation. Since 1990 a program of
controlling P. oregonensis at known feeding stations below the COE
dams has been conducted (Vigg et al. 1990; Parker et al. 1993). In
particular, predation is thought to be the principal source of mortalities
experienced by juvenile emigrants at the Bonneville bypass outfall (Dawley
et al. 1996). Nominal catch rates for the predators below Bonneville have
declined by a half to two thirds during the history of the program.
Indicators of predator abundances in other nearby locations below
Bonneville, such as tailrace density and boat restricted zone (BRZ) density
have also declined (Vigg et al., 1990: Parker et al., 1993).
In the longer term, designing routes of juvenile passage that do not
artificially enhance the ability of native predators to catch smolts is
desirable as a move toward normative conditions. For example, spill has been
shown to disrupt concentrations of predators below dams. High rates of
predation by Caspian terns on juvenile salmon and steelhead at a dredge
spoil island (Ken Collis, CRITFC, personal communication) downstream near
the mouth of the Columbia River were recently discovered. We note that the
degree to which the apparent savings of smolts due to removal of fish
predators may have been offset by the bird predation is a matter of some
concern.
Maintenance of Diversity.
As we pointed out in our transportation review (ISAB 98-2), the bypass
systems are inherently selective with respect to species and stocks, due to
differences among species and stocks in their response to intake screens and
bypass systems. This results in species and stock differences in FGE.
Because one mechanism by which the outfalls increase mortality is predation,
the outfalls necessarily add another element of artificial selection, since
rates of predation are controlled by size of the prey and the water
temperature. Smaller, later emigrants are much more highly vulnerable to the
effects of the present outfall location than are larger earlier emigrants.
Such selectivity, as pointed out above, has the potential of narrowing the
phenotypic variability of the stocks, thereby reducing the population
fitness (Kapuscinski and Lannan 1986).
7. What scientific information is available to compare the present
and proposed Bonneville bypass outfalls to each other, and to other fish
passage strategies such as turbines and spill?
Whether or to what degree the relocation will provide relief from the
presently extraordinarily high levels of bypass mortality cannot actually be
determined until after the bypass outfalls are relocated. However existing
information indicates that relocation could provide some relief by releasing
the juveniles in areas that are less favorable to predators. There is a
considerable volume of research that has established the following
information:
First, predation at or directly below the outfall of the second
powerhouse leads to losses that may be similar to losses in passing through
the turbines, (Dawley et al., 1992; Gilbreath et al., 1993; Ledgerwood et
al., 1991). While these studies demonstrated that mortality of juveniles
within the conduit itself was low, there remained a question whether their
transit through the system might have increased their vulnerability to
predation (Dawley, NMFS, personal communication). Mortality of subyearling
chinook juveniles associated with the bypass at the first powerhouse (either
in transit or after exiting) is high enough to counteract any positive
effects of diversion from the turbine intakes (Ledgerwood et al. 1994). It
is clear that predator abundance is high at the present outfall locations
(Petersen et al., 1993), so that mortality at the outfalls and in the
tailraces is an integral component of overall bypass mortalities.
Secondly, water velocity and depth criteria for locating bypass outfalls
to minimize predation by P. oregonensis are well established and
documented (Poe et al., 1993; Faler et al., 1988; Shively et al., 1996; NMFS/NOAA,
1994 - Appendix D). They have been developed by laboratory studies of the
swimming ability of P. oregonensis at various velocities of flow
(Mesa and Olson, 1993), and by observations of radio tagged P.
oregonensis in the river (Faler et al., 1988; Shively et al., 1996).
a. Are there significant limitations in the scientific
information used to evaluate the Bonneville fish passage strategies (outfall
relocation)? If so, how can the region best fill these information gaps?
Studies at Bonneville first powerhouse do not distinguish mortality rates
of salmon experienced in passage at the outfall, or in the tailrace below
it, from mortalities in the rest of the bypass system. Estimates of
mortality of subyearling chinook salmon passing through the entire first
powerhouse bypass relative to downstream release groups have been made (Ledgerwood
et al. 1994). However, circumstantial evidence on the presence and behavior
of P. oregonensis in the vicinity suggests that losses in the
vicinity of the first powerhouse outfall are probably high. On the other
hand, there is no direct evidence of the effectiveness of the new release
location or of the ability of migrants to tolerate a 1.7-mile-long pipe.
Both will be evaluated in post-construction monitoring. There is a lack of
information on the differential effects of the outfall on survival of
different species and life history types, by size and season. The degree to
which research is warranted to fill these information gaps depends on the
role and purpose of mechanical bypass, as determined by the overall salmon
recovery strategy.
b. Within the constraints of the four operational
scenarios provided by the Council, is the effectiveness of the new
Bonneville bypass outfalls to facilitate survival of juvenile emigrants
strategies adequate to achieve the interim performance objective of 80% fish
passage efficiency and 95% juvenile fish survival at each dam?
The four policy operational scenarios do not appear to affect the
situation at Bonneville Dam. While this question is not relevant to the
relocation of the outfalls at Bonneville Dam per se, it highlights
the need for setting long-term goals in evaluating fish passage. The
existing intake screens alone will not achieve the 80% or 95% short-term
goals. Spill or other measures would be required to achieve the short-term
goals. Obviously, an increase in FGE with improved screens would actually be
harmful if the diverted fish are released from the bypass into an area where
they would experience a rate of mortality that might be higher than they
would experience passing the dam by other routes. In this case attainment of
short-term goals would actually be injurious to salmon recovery.
At Bonneville Dam the effectiveness of bypass will have to be evaluated
after the outfall relocation is complete. Because spill is now required to
achieve the FPE goal, there is a need to know the species composition of
fish in spill and the relative efficacy of spill and other measures for
passage of juvenile emigrants.
c. Does the proposed implementation of bypass
relocation at Bonneville dam have a high probability of achieving the
expected biological benefit (salmon survival improvement) without undue risk
to other anadromous and/or resident fish populations?
The relocation of the bypass outfall has no known expected benefits or
risks for species other than salmon and steelhead as averages over the
season. The bypass outfall relocation is likely to reduce rates of predation
at the outfalls for all species and stocks that are diverted by the intake
screens to a degree that depends on the size of the emigrant and the season
of emigration. Rigorous evaluation and appropriate modification (i.e.,
adaptive management) will be required to assess the results of the outfall
relocation.
d. Does the proposed implementation of bypass
relocation at Bonneville dams provide potentially interim (within the next
10 years) biological benefits, or is it consistent with longer-term
increasingly normative system configuration strategies?
There are both interim and long-term benefits of relocation, although the
long-term benefits are less certain than the short-term. In the interim, the
relocation will solve the predation problems of the existing bypass systems.
On the basis of currently available information, intake screens and the
associated bypass systems are expected to be a part of future, long-term
salmon recovery programs where hydroelectric dams are operated to produce
power at times when juvenile emigrants are present. Increasing normative
strategies such as those that rely on surface bypass and higher spill
amounts may render the bypass outfall location relatively less important to
recovery than it would otherwise be, but the feasibility of these remains to
be demonstrated. Benefits of relocation of the outfall may decrease with
time if predator populations expand, adapt and diversify in response to the
change in habitat in order to take advantage of a concentration of prey.
The outfall is part of the turbine intake bypass system that includes
screens known to operate selectively on different species and life history
types, as we have pointed out in several places, including our response to
the questions on John Day Dam in this report. The search for more effective
means of improving survival of the full diversity of salmon and steelhead
populations needs to be expanded. Until such means are developed, the
decision to relocate the outfalls at Bonneville Dam must be made in
consideration of alleviating the presently high mortalities of subyearling
chinook through the existing bypass system. These mortality rates are
extreme enough that the question of selectivity of the system over time is
secondary to the question of immediate survival.
Bonneville Outfall Relocation Discussion
More individual fish and more stocks pass Bonneville Dam, the lowermost
project on the Columbia River, than at any other project on the river.
Because of this, fish passage improvements at Bonneville Dam are the
"keystone" for realizing the benefits of restoration efforts upstream (FWP:
NWPPC, 1987). Ideally, Bonneville Dam ought to possess a project survival
superior to any other on the river, yet its bypass system is the poorest in
terms of FGE and survival of fish exiting the bypass (Whitney et al., 1997).
Given the lack of success of past mitigation attempts at Bonneville Dam,
what sort of measures should be tried next?
The relative importance of bypass outfall relocation, as well as the
desirability of improving FGE at Bonneville Dam, is a function of the
success of alternative measures for improving survival of juvenile salmon at
the project such as improved spill effectiveness, surface bypass and gas (supersaturation)
abatement. The availability of surface bypass and the feasibility of gas
abatement will influence the policy decisions on what proportion of the
juvenile salmon and steelhead would be passed via spill. Policy makers need
to recognize that decisions for expenditures on FGE improvements, and
expenditures for outfall relocation ought to be balanced against the
probability that other means may be developed for elevating the fish passage
efficiency and the project survival at Bonneville Dam.
From our long-term perspective, measures designed to improve survival of
juvenile salmon may be viewed as being intended to lead to increases in
abundance of adults, though the effects may be smaller than can be measured
with present methods. The inability to date to relate improvements in
survival of juveniles to improvements in adult returns may be due to
numerous factors, including inadequacies in the data or in the approaches
used. Nevertheless, we advise that in making decisions on measures for
salmon protection and enhancement, there be a continued focus on long-term
rather than short-term goals. This will call attention to the fact, as
experience tells us, that large improvements in salmon survival are going to
be required, if we expect to be able to detect them.
The fact that few of the measures undertaken in the past on behalf of
salmon can be demonstrated to have led to increases in adult populations
(restriction of fishing, enforcement, hatcheries and transportation) leads
us to the conclusion that new approaches must be developed and tested.
Innovative and creative approaches need to be fostered, yet examined and
tested rigorously, so that the effective actions can be quickly recognized
and modified further as needed.
Bonneville Recommendation
The high mortality inflicted upon juvenile salmon by predators at the
present bypass outfall locations justifies relocation of the outfalls to
locations and habitats where predation rates are expected to be
significantly reduced. In addition to relocation of the outfall for the
juvenile bypass system, we encourage integrated, long-term planning and
study of other planned alterations. Other planned alterations to the
juvenile fish passage facilities scheduled at Bonneville Dam, include
increasing FGE of intake screens at both powerhouses, replacing the existing
bypass conduits at the powerhouses, joining the two conduits to a common
outfall, investigating surface bypass, and implementing gas abatement
measures (COE briefing to the ISAB). The ISAB recommendation for bypass
outfall relocation does not constitute a blanket endorsement of additional
changes to the rest of the bypass system at Bonneville Dam. The concerns
expressed over the future of mechanical bypass in the portion of this report
dealing with John Day extended length screens also apply to Bonneville.
REFERENCES
Anderson, J., A. Giorgi, J. McKern, H. Schaller, L. Krasnow, S.G. Smith,
C. Toole, E. Weber, J. Williams, and P. Wilson. 1998. Fish guidance
efficiency (FGE) estimates for yearling chinook salmon at Lower Snake and
Columbia river dams. Draft #5. PATH Hydro Work Group, Data Subcommittee.
22pp., plus tables
Robins, C. R., R. M. Bailey, C. E. Bond, J. R. Brooker, E. A. Lachner, R.
N. Lea, and W. B. Scott. 1980. A list of the common and scientific names of
fishes from the United States and Canada (Fourth Edition). Special
Publication No. 12, The American Fisheries Society, Bethesda, Maryland.
Birmingham, A.G., B.H. Ransom, G.W. Tritt, and H. Charvet. 1997. Run
timing of juvenile salmon and steelhead trout passage at Wanapum Dam during
spring 1997. Hydroacoustic Technology, Inc. Report to P. U. D. No. 2 of
Grant County, Ephrata, WA. 44pp, plus appendices
Bonneville Fish Passage, Presentation Team to ISAB on February 17, 1998.
Briefing overheads (tables showing spill efficiency and bypass survival
rates for different project configurations).
Brege, D.A., R.F. Absolon, B.P. Sandford, and D.B. Dey. 1997. Studies to
evaluate the effectiveness of extended-length screens at John Day Dam, 1996.
NMFS/NOAA, Northwest Fisheries Science Center. Report to U.S. Army Corps of
Engineers. Delivery Order E96960028. 41pp
Dawley, E.M., R.D. Ledgerwood, L.G. Gilbreath, B.P. Sandford, P.J.
Bentley, M.H. Schiewe, and S.J. Graboswski. 1992. Survival of juvenile
salmon passing through Bonneville Dam and tailrace. NMFS/NOAA, Northwest
Fisheries Science Center. Report to U.S. Army Corps of Engineers.
Dawley, E, R. Ledgerwood, L. Gilbreath, and P. Bently. 1996. Relative
survival of subyearling chinook salmon that have passed Bonneville Dam via
the spillway, First or Second Powerhouse bypass system or turbines and
tailrace. Research summary incorporating information from several studies
conducted at Bonneville Dam between 1987-1993 under various contracts.
Prepared for U.S. Army Corps of Engineers, Portland District. 10 p.
CRITFC. 1998. Tribal Capital Construction Plan for Bonneville Dam.
Summary to the Independent Scientific Advisory Board.
CRITFC (1995). Wy-Kan-Ush-Mi Wa-Kish-Wit, Spirit of the Salmon, The
Columbia River Anadromous Fish Restoration Plan of the Nez Perce, Umatilla,
Warm Springs, and Yakama Tribes., Volume I. Portland, OR, Columbia River
Inter-Tribal Fish Commission.
NPPC, Northwest Power Planning Council (1994). 1994 Columbia River Basin
Fish and Wildlife Program. Portland, OR, Northwest Power Planning Council.
NRC, National Research Council (1996). Upstream Salmon and Society in the
Pacific Northwest. Washington, D.C., National Academy Press.
Faler, M.P., L.M. Miller, and K. I. Welke. 1988. Effects of variation in
flow on distribution of northern squawfish in the Columbia River below
McNary Dam. North American Journal of Fisheries Management. 8:30-35
Fish Passage Center. 1995. Summary of the 1995 spring and summer juvenile
passage season. Fish Passage Center, Portland, OR. Memo of October 13, 1995.
32pp.
Fishery Agencies and Tribes. 1993. Detailed fishery operating plan with
1994 operating criteria. 44pp plus app. (Available from Fish Passage Center,
Portland, OR)
Gilbreath, L. G., E. M. Dawley, R. D. Ledgerwood, P. J. Bentley, and M.
H. Schiewe. 1993. Relative survival of subyearling chinook salmon that have
passed Bonneville Dam via the spillway or the second powerhouse turbines or
bypass system: adult recoveries through 1991. Report to U. S. Army Corps of
Engineers, Contract E966910013, 18 p plus Appendixes. (Available from
Northwest Fisheries Science Center, 2725 Montlake Boulevard E., Seattle, WA
98112-2097.)
Hansel, H. C., R. S. Shively, G. S. Holmberg, T. P King, T.L. Martinelli,
and M. B. Sheer. 1994. Movements and distribution of radio-tagged northern
squawfish near The Dalles and John Day dams. Pages 17-73 in T. P.
Poe, editor. Significance of selective predation and development of prey
protection measures for juvenile salmonids in the Columbia and Snake river
reservoirs. 1993 Annual Report. Contract DE-AI79-88BP91964, Bonneville Power
Administration, Portland, Oregon.
Issak, D. J., and T. C. Bjornn. 1994. Movements of northern squawfish in
the lower Snake River during 1993. Pages 1-27 in T. P. Poe, editor.
Significance of selective predation and development of prey protection
measures for juvenile salmonids in the Columbia and Snake river reservoirs.
1993 Annual Report. Contract DE-AI79-88BP91964, Bonneville Power
Administration, Portland, Oregon.
Iwamoto, R.. and J.G. Williams. 1993. Juvenile salmonid passage and
survival through turbines. NMFS/NOAA, Northwest Fisheries Science Center.
Report to U.S. Army Corps of Engineers. Project E86920049. 27pp
Krcma, R.F., W.E. Farr, and C.W. Long. 1980. Research to develop bar
screens for guiding juvenile salmonids out of turbine intakes at low head
dams on the Columbia and Snake rivers, 1977-79. NMFS/NOAA, Northwest
Fisheries Science Center. Report to U.S. Army Corps of Engineers. Contracts
DACW75-79-F-0163 and DACW57-79-F-0274. 28 pp, plus appendices
Krcma, R.F., D.A. DeHart, M. Gessel, C.W. Long, and C.W. Sims. 1981.
Evaluation of submersible traveling screens, passage of salmonids through
the ice-trash sluiceway, and cycling of gatewell orifice operations at
Bonneville first powerhouse, 1981. NMFS/NOAA, Northwest Fisheries Science
Center. Report to U.S. Army Corps of Engineers. Contract DACW57-81-F-0343,
61pp
Krcma, R.F., D.A. DeHart, M.H. Gessel, C.W. Long, and C.W. Sims. 1982.
Evaluation of submersible traveling screens, passage of juvenile salmonids
through the ice-trash sluiceway, and cycling of gatewell orifice operations
at the Bonneville First Powerhouse, 1981. NMFS/NOAA, Northwest Fisheries
Science Center. Report to U.S. Army Corps of Engineers. Contract
DACW57-81-F-0343.
Krcma, R.F., M.F. Gessel, W.D. Muir, C.S. McCutcheon, L.G. Gilbreath, and
B.H. Monk. 1984. Evaluation of the juvenile collection and bypass system at
Bonneville Dam, 1983. NMFS/NOAA, Northwest Fisheries Science Center. Report
to U.S. Army Corps of Engineers. Delivery Order DACW57-83-F-0315. 56pp. plus
appendices
Kapuscinski, A. R. D. and J. E. Lannan (1986). "A conceptual genetic
fitness model for Fisheries Management." Canadian Journal of Fisheries and
Aquatic Sciences 43: 1606-1616.
Ledgerwood, R., E. Dawley, L. Gilbreath, P. Bentley, B. Sandford, and M.
Schiewe. 1990. Relative survival of subyearling chinook salmon which have
passed Bonneville Dam via the spillway or the Second Powerhouse turbines or
bypass system in 1989, with comparisons to 1987 and 1988. Report to U. S.
Army Corps of Engineers, Contract E85890024/E85890097, 64 p + Appendixes.
(Available from Northwest Fisheries Science Center, 2725 Montlake Boulevard
E., Seattle, WA 98112-2097.)
Ledgerwood, R.D., E.M. Dawley, L.G. Gilbreath, B.J. Bentley, B.P.
Sandford, and M.W. Schiewe. 1991. Relative survival of subyearling chinook
salmon that have passed through the turbines or bypass system of Bonneville
Dam Second Powerhouse., 1990. NMFS/NOAA, Northwest Fisheries Science Center.
Report to the U.S. Army Corps fo Engineers. Delivery Order E86900104. 90pp.
Ledgerwood, R., E. Dawley, L. Gilbreath, L. Parker, B. Sandford, and S.
Grabowski. 1994. Relative survival of subyearling chinook salmon after
passage through the bypass system at the First Powerhouse or a turbine at
the First or Second Powerhouse and through the tailrace basins at Bonneville
Dam, 1992. Report to U. S. Army Corps of Engineers, Contract
DACW57-85-H-001, 53 p. + Appendices. (Available from Northwest Fisheries
Science Center, 2725 Montlake Boulevard E., Seattle, WA 98112-2097.)
Matthews, G.M., D.L. Park, J.R. Harmon, C.S. McCutcheon, and A.J.
Novotny. 1987. Evaluation of transportation of juvenile salmonids and
related research on the Columbia and Snake rivers - 1986. NMFS/NOAA,
Northwest Fisheries Science Center.
Matthews, G. M. 1992. An overview of twenty years of research on
transportation of yearling chinook smolts. Proceedings of a technical
workshop, University of Idaho, February 26-28, 1992. Coastal Zone and
Estuarine Studies Division, Northwest Fisheries Science Center, National
Marine Fisheries Service, Seattle, Washington.
McComas et al. 1993. Studies to determine the effectiveness of
extended-length submersible bar screens at McNary Dam in 1992. National
Marine Fisheries Service. Northwest Fisheries Science Center Coastal Zone
and Estuarine Studies Division. Seattle, Washington.
McComas et al. 1994. Studies to Evaluate the Effectiveness of
Extended-length screens at McNary Dam, 1993. National Marine Fisheries
Service. Coastal Zone and Estuarine Studies Division. Seattle, Washington.
Mesa, M.G.. 1994. Effects of multiple acute stressors on the predator
avoidance ability and physiology of juvenile chinook salmon. Transactions of
the American Fisheries Society 123:786-793
Mesa, M.G., and T.M. Olson. 1993. Prolonged swimming performance of
northern squawfish. Transactions of the American Fisheries Society
122:1104-1110
Mesa, M. G., T.P. Poe, D.M. Gadomski, and J.H. Petersen. 1994. Are all
prey created equal? A review and synthesis of differential predation on prey
in substandard condition. Journal of Fish Biology (1994) 45 (Supplement A),
81-96
Muir, W., S. Smith, K. McIntyre, and B. Sandford. 1998a. Project survival
of juvenile salmonids passing through the bypass system, turbines, and
spillways with and without flow deflectors at Little Goose Dam, 1997. Draft
report to U.S. Army Corps of Engineers, Contract E86970085. (Available from
Northwest Fisheries Science Center, 2725 Montlake Boulevard E., Seattle, WA
98112-2097.)
Muir, W., S. Smith, E. Hockersmith, M. Eppard, W. Conner, and B. Arnsberg.
1998b. Passage survival of hatchery subyearling fall chinook salmon to Lower
Granite, Little Goose, and Lower Monumental Dams, 1996. Chapter 2 In
J.G. Williams and T. C. Bjornn, editors. Fall chinook salmon survival and
supplementation studies in the Snake River Reservoirs, 1996. (Available from
Northwest Fisheries Science Center, 2725 Montlake Boulevard E., Seattle, WA
98112-2097.)
NMFS/NOAA (National Marine Fisheries Service). 1994. Juvenile fish screen
criteria. Appendix D in Proposed Recovery Plan for Snake River
Salmon. National Marine Fisheries Service Environmental and Technical
Services Division, Portland, OR
NWPPC (Northwest Power Planning Council). 1987. Columbia Basin Fish and
Wildlife Program. Northwest Power Planning Council, Portland, OR. 246 pp.
Oregon State radio-telemetry studies cited in CRITFC, 1998.
Parker, B. L., K. Collis, B. Ashe, R. E. Beaty, and K. McRae. 1993.
Controlled angling for northern squawfish at selected dams on the Columbia
and Snake rivers in 1992. Pages 129-182 in C. F. Willis and A. A.
Nigro, editors. Development of a system-wide predator control program:
stepwise implementation of a predation index, predator control fisheries,
and evaluation plan in the Columbia River Basin. 1992 Annual Report.
Contract DE-BI79-90BP07084, Bonneville Power Administration, Portland,
Oregon.
Petersen, J.H., D.M. Gadomski, and T.P. Poe. 1994. Differential predation
by northern squawfish (Ptychocheilus oregonensis) on live and dead
juvenile salmonids in the Bonneville Dam tailrace (Columbia River). Canadian
Journal of Aquatic Sciences 51:1197-1204
Poe, T.P., M.G. Mesa, R.S. Shively, and R.D. Peters. 1994. Development of
biological criteria for siting and operation of juvenile fish bypass
systems: Implications for protecting juvenile salmonids from predation. Pp.
169-176 in K. Bates (ed.) 1994. Fish Passage Policy and
Technology. Symposium Proceedings. American Fisheries Society Annual
Meeting, 1993
Ransom, B.H. 1997. Summary of spillway and sluiceway effectiveness in
passing juvenile salmonids at Wanapum and Priest Rapids dams from 1980-1996.
Hydroacoustic Technology, Inc. Report to P.U.D. No.2 of Grant County,
Ephrata, WA. 5pp, plus appendices
Raymond, H.L. and C.W. Sims. 1980. Assessment of smolt migration and
passage enhancement studies for 1979. NMFS/NOAA, Northwest Fisheries Science
Center, Seattle, WA. Report to U.S. Army Corps of Engineers: 48pp
Rieman, B. E., R. C. Beamesderfer, S. Vigg, and T. P. Poe. 1991.
Estimated loss of juvenile salmonids to predation by northern squawfish,
walleye, and smallmouth bass in John Day Reservoir, Columbia River.
Transactions of the American Fisheries Society 120:448-458.
Ruff, Jim. 1998. Technical Background Paper-Review of the Columbia River
Fish Mitigation Program. Review Draft.
Sheer, M.B., G.S. Holmberg, R.S. Shively, H.C. Hansel, T.L. Martinelli,
T.P. King, C.N. Frost, T.P. Poe, J.C. Snelling, and C.B.Schreck. Movement
and behavior of radio-tagged juvenile spring and fall chinook salmon in The
Dalles and John Day Dam Forebays, 1995. National Biological Service.
Columbia River Research Laboratory. Cook, Washington in cooperation with the
Oregon Cooperative Fishery Research Unit. Department of Fisheries and
Wildlife. Oregon State University. Corvallis, Oregon.
Shively, R.S., T.P. Poe, and M.B. Sheer. 1996. Criteria for reducing
predation by northern squawfish near juvenile salmonid bypass outfalls at
Columbia River dams. Regulated Rivers: Research and Management 12:493-500
Sims, C.W., and R. Johnson. 1977. Evaluation of the fingerling bypass
system at John Day Dam and fingerling bypass outfall at McNary Dam. NMFS/NOAA,
Northwest Fisheries Science Center. Report to U.S. Army Corps of Engineers.
15pp., plus appendices
Vigg, S., C. C. Burley, D. L. Ward, C. Mallette, S. Smith, and M.
Zimmerman. 1990. Development of a system-wide predator control program:
stepwise implementation of a predation index, predator control fisheries,
and evaluation plan in the Columbia River Basin. Pages 261-326 in A.
A. Nigro, editor. Development of a system-wide predator control program:
stepwise implementation of a predation index, predator control fisheries,
and evaluation plan in the Columbia River Basin. 1990 Annual Report.
Contract DE-BI79-90BP07084, Bonneville Power Administration, Portland,
Oregon.
Weber, K. 1954. Testing the effect of a Bonneville draft tube on
fingerling salmon. Unpublished Report. U.S. Fish and Wildlife Service. [As
summarized by Iwamoto and Williams, 1993.]
Whitney, R.R., L.D. Calvin, M. W. Erho, Jr., and C.C. Coutant. 1997.
Downstream passage for salmon at hydroelectric projects in the Columbia
River Basin: Development, installation, and evaluation. Northwest Power
Planning Council, Portland, OR. Report No. 97-15. 101 pp.
^ top
|
|
home