Wildfires and Water Quality

The Upper Feather River Watershed is one of California’s regions of highest precipitation. Its runoff provides the majority of water delivered by the State Water Project, an average 3.2 million-acre feet each year feeding into Lake Oroville.

Clear Lake, the largest natural lake entirely within California, has a severe problem with harmful algal blooms which can be detrimental to aquatic life by depriving it of oxygen when the algae dies, sinks, and decays. A driving factor of these conditions are the nutrient loads being carried into the lake by soil erosion and the transport of sediment from the lake’s tributaries. Recently, an...

Large wildfires have increased in size and frequency in the western United States over the past several decades. This has led to increased soil erosion and the transport of sediment containing nutrients into streams and reservoirs. Excess nutrients typically lead to the increased production of algae which can then lead to low levels of dissolved oxygen. This degrades the habitat for fish and...

In California, drought and warmer climates have increased the prevalence, severity, and duration of wildfires. These fires have destroyed over 129 million trees. In the aftermath of this devastation, there is heightened urgency to increase the capacity of seedling production, particularly for the lower-elevation and private lands that CAL FIRE is responsible to help manage. To support CAL FIRE in...

The frequency of fire in southern California forests has steadily increased over time as a result of ignitions at the growing wildland-urban interface, as well as a result of warming due to climate change. Understanding the implications of increased wildfire on hydrologic conditions and water supply is particularly important given the increasing demands for water resources to satisfy growing...

Over the last several decades, both the incidence of large wildfires and the duration of the wildfire season across much of the United States have increased (Westerling and others, 2006, American Water Works Assn, 2008; Finco and others, 2012). Future wildfire projections based on forecasted climate scenarios indicate both an increase in the expected severity of wildfires, and an expansion of...

The Rim Fire has burned over 400 square miles of the Tuolumne River and Merced River watersheds in central California and is now the 3rd largest wildfire in state history. The burn area is largely on the Tuolumne between Hetch Hetchy Reservoir and Don Pedro Reservoir, both of which serve as critical sources of drinking water and irrigation water to San Francisco Bay area and Central Valley...

Reservoirs naturally fill with sediment transported from the upstream watershed. As reservoirs fill with sediment, the amount of available water decreases for functions such as water supply, irrigation, flood control, and hydropower. In the Sierra Nevada Mountains of California, a large number of reservoirs are significantly affected by reservoir sedimentation (Minear and Kondolf 2009). Factors...

Fast-moving, highly destructive debris flows triggered by intense rainfall are one of the most dangerous post-fire hazards. The risk of floods and debris flows after fires increases due to vegetation loss and soil exposure. Cases of sudden and deadly debris flow are well documented along the western United States, particularly in Southern California. These flows are a risk to life and property...

About half of the water supply in the southwestern United States is supplied by water from forests, which generally yield higher quality water than any other source. Approximately 80 percent of the freshwater resources in the U.S. originate on forested land, and more than 3,400 public drinking-water systems are located in watersheds containing national forest lands (USDA, 2006). More than 12...