Topic: 2011-Spring Spills in Pit 3, 4, & 5.
|Posted: Jun 8, 2011Post Subject: 2011-Spring Spills in Pit 3, 4, & 5.
|PG&E is observing rapidly increasing inflows into Lake Britton and as a result anticipates that Pit 3 Dam will spill. PG&E has taken careful steps to manage the increasing inflow into Lake Britton by monitoring reservoir level, maintaining a low water surface elevation, and has increased water diversion through Pit 3 and Pit 4 powerhouses to maintain appropriate storage capacity. The increased water diversion at Pit 3 and Pit 4 powerhouses will result in spill conditions today in the Pit 5 bypass reach. The current flow release from Pit 5 Dam is approximately 500 cfs, which will increase over the course of today to approximately 1000 cfs to 1500 cfs. As inflow to Lake Britton continues to increase over the coming days, PG&E will increase the instream flow release at Pit 3 Dam from about 300 cfs to 540 cfs. Shortly after the instream flow in the Pit 3 reach is increased, Pit 4 dam will begin to spill approximately 50 to 150 cfs. Subsequent inflow increases into Lake Britton will spill over the Pit 3 Dam at a natural rate of increase, and will affect the downstream spill magnitude in the Pit 4 and Pit 5 reaches.|
At this time PG&E is unable to accurately provide an estimate of the anticipated spill magnitude in the Pit 3 and Pit 4 reaches, as inflow to Lake Britton continues to increase daily and record snow pack remains in the Warner Mountain Rage.
Following the snow melt runoff period, which may extend for several weeks, PG&E will allow the spill flows to recede naturally to the license required seasonal minimum instream flow.
|Thanks for the info.