Supes, MMWD Eye Making Phoenix Lake a Flood Basin

The Marin County Board of Supervisors, operating as the Flood Control District 9 Board, approved a $49,000 contract this week with Stetson Engineering to prepare a grant application for funding to turn Phoenix Lake into a flood detention basin.

Flood prevention efforts have been in the works for Flood District 9 since a per-parcel flood fee was approved by voters in 2007. The mail-in vote was challenged in court before being ruled legal by the California Supreme Court last summer.

, which centered on a hydraulic model of the watershed, was a proposal to establish flood detention basins to hold run-off during heavy rains.

According to the staff recommendation letter to the Supervisors on Feb. 1, Phoenix Lake was the largest of the possible detention basins identified. Additionally, the Marin Municipal Water District (MMWD) has agreed to study the proposal and is in talks with engineering staff over the the best way to create such a run-off basin. The MMWD Watershed Committee will discuss the proposal at their meeting today at 1:30 p.m.

The lake would continue to operate regularly most of the year, but during heavy rains water would be diverted from the creek to prevent spillover and flooding. The water would, then, be released back into the creek after the flood danger had passed.

The project -- which includes excavation of the bottom of the lake, a mechanical dam in the spillway, installation of lower level outlets, and strengthening of the dam -- would cost around $20 million. 

The $49,000, approved by the Board of Supervisors, would be for Stetson Engineering to prepare a grant application for the California Department of Water Resources. The department issued a call for projects that have benefits for flood control, water supply, water quality, and habitat improvements.

"We think this project answers what they're looking for," said Jack Curley, a county engineer with the flood district.

The department is awarding $220 million worth of grants up to $30 million each, with a 50 percent contribution from the local agency.