The dynamic Sacramento River

We need to care for it—or it won’t care for us

The author is retired from teaching biology at Chico State, where he was an expert on vernal pools.

Sacramento River flooding is difficult to control when storms move massive amounts of water from the Pacific Ocean into California. Fortunately, these extreme climatic conditions that produce floods rarely occur.

In past centuries, the Sacramento River Valley contained river forests that tolerated and benefited from potentially large floods. Past river channels displaced a great distance from the present-day river illustrate the major impact of the river on the landscape. The laterally moving river cut into forests, leaving sediments on the withdrawing side.

Vegetation invaded the sediments, producing bands of forests supporting many different plants and animals. The river had a complex food web. This included large adult salmon swimming upriver after years of ocean growth as well as their young attempting to swim to the ocean after early development in fresh water.

Past and current human land-use activities such as hydraulic mining, construction of levees and dams, agricultural development, forestry practices and building houses and roads directly and indirectly change the watershed. All valley developments remain susceptible to flood damage.

Agricultural development benefits from irrigation water provided to plants growing on soils originally built up by the river. The slow release of water deposited in mountain forests as winter snow and rain, along with our reservoir systems, supports summer water needs. Additionally, groundwater recharged during higher-rainfall years supports valley life during lower-rainfall years. Because the use and recharge of groundwater is displaced over years, loss of this resource is hard to detect.

Restoration specialists such as Chico’s River Partners are replacing farm land susceptible to flooding with native landscapes that tolerate flooding. These areas provide environmental services by reducing flood losses to adjacent areas. They also support natural biodiversity, tourism, hunting and fishing. Economic and social issues control further expansion of these natural areas.

Land-use patterns throughout the watershed, as well as the transfer of water to Southern California, are affecting the future stability of a large area extending from Northern California through the Delta to San Francisco Bay. The major rainfall differences from year to year challenge our attempts to regulate water use.

A combination of cooperation and compassion among different political and economic interests is needed to maintain current land use, especially during times of drought and catastrophic storms.