In a few days the Pit River below the Lake Britton Dam will grow by nearly ten times the usual volume of water. PG&E operates several hydroelectric dams along the Pit River and a tunnel delivers water from Lake Britton to the Pit 3 Powerhouse. That tunnel needs maintenance so the water that usually flows through it will spill over the dam starting on Monday. The flows in the Pit 3 reach will increase from 300 cubic feet per second to about 2900 cubic feet per second. The flow will remain at that level through mid-April, when water will again be diverted through the tunnel. Despite years of drought, flows in the Pit River have remained at normal levels because it’s fed by springs percolating from volcanic aquifers.