El Dorado Irrigation District
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Summary
The El Dorado Irrigation District (EID) is currently planning improvements for the El Dorado Hills Water Treatment Plant (EDHWTP), a comprehensive modernization and expansion effort designed to replace aging infrastructure, enhance treatment reliability and resilience, address seasonal source‑water challenges from Folsom Lake, and ensure the facility can continue meeting current and future drinking water regulations and demands through upgraded treatment processes and increased operational capacity.
The timing for construction of the planned improvements depends on securing grant funding or other financing, and EID is currently advancing design and environmental review to ensure the project remains eligible and competitive for upcoming funding opportunities.
Background
The EDHWTP is owned and operated by EID and serves drinking water to the western portion of EID’s service area, which includes El Dorado Hills and the surrounding communities. EID supplies raw water to EDHWTP from a recently replaced intake facility located on the south shore of Folsom Lake.
EDHWTP was originally constructed in the 1960s with upgrades performed during the 1990s, 2000s, and 2010s. EDHWTP operates year-round and faces a variety of seasonal operational challenges, such as:
- During the summer, as water use rises sharply during the hottest and driest months of the year, the EDHWTP’s current operational capacity of 19.5 million gallons per day (mgd) is nearing its ability to meet daily peak drinking water demands. The current capacity constraint requires EID to supplement EDHWTP water supplies with other supplies through a complex array of infrastructure and operations throughout EID’s service area.
- During the late summer and fall, water quality conditions in Folsom Lake, such as higher temperatures and algae growth, create operational challenges by reducing drinking water production.
- In the winter and spring, runoff from wildfire-affected watersheds carries elevated sediment, ash, and debris to Folsom Lake, producing source water with higher turbidity and more demanding treatment conditions.
EID’s 2024 Water and Recycled Water Master Plan, along with other technical evaluations of the EDHWTP, identifies aging infrastructure at the plant as a key driver of ongoing operational challenges. These evaluations recommend infrastructure and process improvements to ensure the facility remains reliable, resilient, and capable of meeting current and future water quality standards and customer demands.