Above the San Joaquin


levees, agriculture, and urban development built in the floodplain, San Joaquin, CA | Julie Fair, flight by LightHawk

Levees, agriculture, and urban development built in the floodplain, San Joaquin, CA | Julie Fair, with aerial assistance provided by LightHawk

Nothing will truly show you the extent to which California’s rivers have been augmented like a view from the air. Thanks to a donation from LightHawk, I recently had the opportunity to fly over the San Joaquin River and experience, first hand, the plumbing of one of California’s largest and most important rivers.

Despite living in California for most of my life, prior to this year’s Most Endangered Rivers® listing, I knew fairly little about the San Joaquin. I knew the San Joaquin was a major river, collecting flows from several major tributaries along the Western Sierra and I knew its water was used extensively for agriculture and municipal use, but I had no idea about the extent of its plumbing. As noted in our Patagonia intern’s blog from a couple weeks ago, the most shocking features were Friant Dam, and Mendota Pool. Friant Dam, at the edge of the foothills, diverts the majority of San Joaquin flows coming out of the Sierra for irrigation and municipal use. This causes the San Joaquin to run dry for over 60 miles until the Mendota pool, where it is re-watered by delta water via the Delta-Mendota Canal.

But that’s far from the only San Joaquin plumbing I observed. I also saw countless miles of irrigation canals stretching as far as I could see in every direction. These canals divert flow from the San Joaquin for irrigation, contributing to greatly reduced flows in the river. As an example, at one site I saw a canal full of water running alongside a dry reach of the San Joaquin. The greatly reduced flows in the San Joaquin created by these irrigation diversions and Friant Dam, combined with excessive runoff from agriculture have led to elevated levels of pesticides and fertilizers. This has led to severe water quality problems in the lower San Joaquin and Sacramento-San Joaquin River Delta that impact communities and wildlife.

On our flight, I also saw mile after mile of the San Joaquin narrowly confined on both sides by levees. This may seem like a familiar sight to those familiar with Central Valley rivers, but it is far from the natural condition. These levees were put in place to contain peak flows and prevent them from damaging adjacent farmland and urban development that lies in the river’s natural floodplain. Under natural conditions, high flows would have overtopped the river’s banks and spread out across this floodplain slowing and dissipating along the way. This flooding would have created acres of important shallow water rearing habitat for Chinook salmon. Instead, these flows are now confined and quickly shuttled downstream where they increase the risk of flooding for major metropolitan areas like Stockton and Sacramento. Rearing habitat is greatly diminished and contributes to the major decline in Chinook salmon in the San Joaquin.

Fortunately, there are great opportunities to restore the San Joaquin. A settlement agreement that calls for enough flows to re-water the dry reach of the San Joaquin was passed in 2006, a number of key floodplain restoration projects are underway, and the California State Water Resources Control Board is developing a new plan for management of the river. The key now, especially in the current drought, is to maintain this forward momentum by urging state and federal agencies to protect and enhance flows and continue to restore the San Joaquin.