It’s that time of year again — birdsong is in the air, the hills are turning brown and the big rubber inflatable dam on the Russian River near Forestville is getting pumped full of air. 

The Sonoma County Water Agency will start inflating the dam Monday and it could take from four days to two weeks to get the thing completely full. 

The annual inflation process takes place in spring or early summer and is key to water deliveries for many of Sonoma Water’s 600,000 customers in Sonoma and Marin counties. 

Once inflated, the dam creates an upstream pool from which water is drawn into four off-stream infiltration ponds, according to Sonoma Water officials. 

The ponds help recharge groundwater in the area at a time of year when water demand begins to increase.  

The Western States Water Council takes a tour of the Sonoma County Water Agency Mirabel inflatable dam and fish ladder on the Russian River in Sonoma County, Calif., on June 27, 2017. (Photo courtesy Florence Low/California Department of Water Resources)

The dam is downstream of the Wohler Bridge and a fish ladder helps salmon and steelhead make their way upstream around the dam. An underwater video system helps officials count migrating fish populations.

Boaters are required to carry their boats around the dam and people aren’t allowed to play on or near it.

Also, California Department of Fish and Wildlife regulations prohibit fishing within 250 feet of the dam in either direction.

Kiley Russell writes primarily for Local News Matters on issues related to equity and the environment. A Bay Area native, he has lived most of his life in Oakland. He studied journalism at San Francisco State University, worked for the Associated Press and the former Contra Costa Times, among other outlets. He has covered everything from state legislatures, local governments, federal and state courts, crime, growth and development, political campaigns of various stripes, wildfires and the aftermath of Hurricane Katrina.