How does Lodi Lake get filled?

The Mokelumne River to the north fills Lodi Lake. As the river moves downstream from the Nature Area, it reaches the concrete Woodbridge Diversion Dam. The dam blocks some of the river’s flow, causing the water to collect behind it, creating Lodi Lake.

Every year in late February, the Woodbridge Irrigation District (WID) temporarily lowers the dam, draining the lake completely and leaving it looking like a mud pit. Any fish in the lake usually move downstream with outgoing water; if they get trapped, they make easy treats for the pelicans and egrets. WID uses this time for maintenance on irrigation canals and fish screens that normally have water flowing through them. After about four weeks, they raise the dam again and river water recreates the lake, filling up to its usual 12-foot depth.