Laguna de Santa Rosa
From the Laguna de Santa Rosa Foundation website:
At one time the Laguna de Santa Rosa consisted of wide expanses of oak woodland, deep riparian forests, lakes, perennial and seasonal freshwater wetlands. Herds of elk and pronghorn antelope were hunted by Native Americans, mountain lions and grizzly bears. Tens of thousands of migratory birds relied on the Laguna flood waters in the winter and its rich food and shelter resources for breeding and nesting in the summer.
Where once swales and marshes formed and rainfall slowed and ponded in vernal pools throughout the valley, water now rushes in concentrated flow to the Laguna where it is joined by runoff from the western hills. Although the natural drainage system is now confined to the western third of the valley, it remains an impressive 14-mile-long waterway, with a floodplain of more than 7500 acres.
The floodplain and adjacent uplands contain many distinctive natural features, including braided channels, pools, springs, seasonal and perennial wetlands, and riparian and oak woodland. In the summer these features are separate and distinct, but in the winter they can appear as one vast lake. The Laguna watershed comprises approximately ten percent of the entire Russian River drainage; and when the river floods, the Laguna can act as a huge natural reservoir, storing up to 80,000 acre-feet of water. For the residents of Guerneville, this can result in a 14-foot reduction in the height of the 100-year flood.