Will El Nino really bring relief for California’s water supply?

American River

The Middle Fork of the American River, heavy with top soil from the burned slopes of the King Fire, merges with the North Fork near Auburn, CA.

The last few weeks have been busy for firefighters in California, and depending on the weather we get, it could end up being a busy winter for water and hydropower managers, too.   

Several wildfires have burned along important river corridors in the Sierra Nevada over the last few weeks. The Kyburz Fire started next to Highway 50, burning along the South Fork of the American River- a key contributor to Folsom Lake which provides drinking water to the cities of Folsom, Sacramento, and El Dorado Hills, and serves farms in the valley through the Federal Central Valley Project. The South Fork of the American River is also an important hydropower provider – the Sacramento Municipal Utility District can supply up to 20% of their customers’ electricity needs through their system along the Upper American River. The Lowell Fire in Nevada County burned along the Steep Hollow drainage, a tributary to the Bear River and part of the system that feeds the Nevada Irrigation District’s (NID) hydropower and drinking water supply systems. NID supplies water to nearly 25,000 homes, farms and businesses in Nevada and Placer counties. Their hydropower system generates electricity to supply the equivalent of more than 60,000 homes, and feeds into the Pacific Gas and Electric Company’s grid. The Willow Fire near Bass Lake in Madera County continues to burn along Willow Creek in the headwaters of the San Joaquin River, which feeds Millerton Lake and is an important source of water for agriculture in the South San Joaquin Valley.  

It’s still too early to tell whether these fires burned at high enough intensity to result in a large amount of damage, and they may even end up being ecologically beneficial. Either way, it’s important to recognize that wildfire in the Sierra Nevada has a direct impact on California’s water and power. Each of these watersheds are of critical importance to both the local system and to a larger network that supplies Californians with water and energy. Whether it helps to thin underbrush and protect water and power resources, or whether it destroys everything in its path, wildfire and forest health play a big role in the long-term reliability of California’s water system.  

The forests that line the slopes along river corridors stabilize the soil, holding it to the hillside and slowing runoff into the waterway. When that vegetation is severely burned, as it was in several areas during the King and Rim Fires, the plants and trees die, their roots decay, and there’s nothing to keep the soil from sliding in to the river. The result is what Placer County Water Agency (PCWA) has been experiencing following last summer’s King Fire. Even with the ongoing drought, the minimal rain events that we have had have washed top soil from the burned area into the Rubicon River, impacting water quality and reducing capacity in PCWA’s reservoirs. PCWA has already spent over a million dollars protecting water and power infrastructure following the King Fire. If the predictions of a strong El Nino are true, the coming large precipitation events have the potential to cause a significant amount of damage to water and power infrastructure downstream.  

We often focus on the local impacts of fires when they occur – the evacuations, the road closures, even the local air quality impacts – but there are also long-term impacts that affect all of California. As our climate gets warmer, wildfires in the Sierra Nevada are likely to become more frequent and more damaging. Without a coordinated effort to restore our forests and change the way fire burns through the Sierra Nevada, California’s water and hydropower systems may continue to be at risk.   

That is why the Sierra Nevada Conservancy has partnered with the U.S. Forest Service to launch theSierra Nevada Watershed Improvement Program – a coordinated, integrated, collaborative program to restore watershed health in the Sierra Nevada. Over the next year, the SNC, the U.S. Forest Service, and a wide variety of other state and federal agencies, non-governmental organizations, local governments, Tribes, and private landowners will be working together to identify the true restoration needs in the Sierra Nevada, and establish a list of investments that can be made to protect water quality; reduce the risk of large, damaging wildfires; stabilize carbon storage; restore critical habitat; protect recreational resources; and improve the overall health of our Sierra forests.   

Continuing down our current path in the Sierra is not an option. Let’s change the direction of that path, and instead move towards a healthy Sierra Nevada Region and a healthy future for California.