Slide 4 of 9 Notes:  

---

This hydro block is generally never used.  However, some would argue that in an emergency, this block could be used if all other resources were already in use and if there were some likelihood of recovering to normal elevations in later months.  All operational constrains except the daily rate-of-draft limit are violated.  Physical constraints are not violated.  About 5,000 MW-months of energy is kept in the system for stability purposes (according to planners at BPA).  This hydro block is fairly large, averaging just under 8,000 MW.  It is, however, a very inefficient block of hydro energy, meaning that to get it out generally means that we spill at a number of dams.