Lake Mendocino would contain an additional 24,000 acre feet of water -#8212; about 7.8 billion gallons -#8212; had the U.S. Army Corps of Engineers held onto stormwater from January 2013, the last time there was a significant downpour, according to a local water agency.
Instead, lake levels have dropped to near record lows and Mendocino County officials are considering a water emergency declaration next week.
The water that was released downstream from the lake early last year is almost as much as the amount that now remains, just over 26,000 acre feet. It was enough to supply roughly 48,000 households for a year.
The water was discarded because the Army Corps is required to follow a rigid water-release schedule in winter.
"It's kind of crazy," said Sean White, manager of the Russian River Flood Control and Water Conservation Improvement District. The Russian River water district oversees the Ukiah Valley's 8,000 acre-foot right to water in Lake Mendocino.
"What we need are new rules that are reflective of modern technology," White said.
Army Corps officials said technology has yet to provide a foolproof mechanism for predicting storms that could cause severe flooding.
"The whole purpose of the graph is keeping the dam safe," said Mike Dillabough, chief of the Operations and Readiness Division for the Army Corps' San Francisco District.
The primary reason the dam at Lake Mendocino was built was to prevent flooding.
Under a worst case scenario that includes a complete dam failure, roughly 250,000 people between Lake Mendocino and Jenner could be adversely affected by flooding, Dillabough said.