New study predicts how weather changes will impact future water supplies

Updated September 02, 2022
New study predicts how weather changes will impact future water supplies

Study underscores need to continue investments to diversify, modernize water systems

Communities that rely on surface water supplies from the American River and Folsom Reservoir must modernize and diversify their water supply, storage, and delivery infrastructure to adapt to changing weather patterns. This is the conclusion of a new study published by the U.S. Bureau of Reclamation and sponsored by several local water agencies, including the City of Roseville.

The American River Basin Study analyzes how changing weather patterns will impact the timing, magnitude, and type of precipitation in the future (rain vs. snow). The American River Basin includes the American River watershed, which stretches from roughly Interstate 80 to Highway 50 and from the high Sierra Nevada to Sacramento.

The study forecasts that temperatures will rise by six degrees, and the high mountain snowpack that traditionally stores water supplies until spring will be reduced by 50 percent by the end of this century. More precipitation will arrive as rain in the watershed, and the majority of water runoff will flow into Folsom Reservoir in January through March, rather than April through June.

Folsom Reservoir is the major water supply source for the City of Roseville. It is managed by the U.S. Bureau of Reclamation. It is historically operated for flood control operations during the winter and as storage for snowpack runoff in the spring to meet urban and environmental needs later in the year.

In light of changing weather patterns and precipitation, Roseville and other water providers are developing infrastructure better suited for collecting earlier rainfall, instead of later snowmelt and alternatives to Folsom Reservoir.

  • Groundwater Banking: Roseville has several groundwater wells throughout the City that can pump water underground when it is available and draw that water out of the ground when we need additional supplies. These Aquifer Storage and Recovery (ASR) wells are key to utilizing the aquifer as a water storage bank. This allows the City to take in additional surface water (which would otherwise be spilled from Folsom Reservoir) that can be drawn as an alternative supply during dry seasons. The City is currently constructing two additional ASR wells and has two more planned for the future. The City’s ASR program is conducted in collaboration with larger regional groundwater banking efforts.

  • Additional Conveyance (Pipes): Roseville is working with Placer County Water Agency (PCWA) on two infrastructure projects that will allow water supplies to be delivered into the City, including PCWA contracted water that would normally be drawn out of Folsom Reservoir. One project would construct additional pipes to move treated PCWA water from other locations in West Placer into Roseville. The City is also studying another project to move untreated water from PCWA’s territory to the City’s water treatment plant. Together, these projects would allow millions of gallons of water to be piped every day to Roseville, without depending on plumbing from Folsom Reservoir. To pay for a portion of these projects, the City and PCWA are optimistic that Senator Alex Padilla’s support of a $21 million federal authorization pending before Congress as part of the Water Resources Development Act will be enacted into law later this fall.

  • Alternative Intake at Folsom: Roseville is working with the City of Folsom and San Juan Water District to study an alternative intake at Folsom Reservoir. The current intake becomes “daylighted” and inoperable when water levels drop to low levels. This study project is looking at alternative pipes and pumps that could make surface water supplies from Folsom Reservoir more reliable in dry years and at lower water levels.

“The ARBS confirms the need for Roseville to continue our efforts to develop and diversify our local water supplies and modernize our water delivery infrastructure, particularly to address our reliance on a single intake point at Folsom Reservoir,” said Sean Bigley, assistant director of water for the City of Roseville. “Although we have adequate and reliable water supplies today, we need to plan ahead and take action to ensure we can continue to have a reliable water supply for our residents and businesses and maintain a high quality of life and a thriving economy.” 

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