Clear Lake Rehabilitation

Overview of UC Davis Work

Piloting a Potential Solution for Clear Lake

UC Davis is piloting a Hypolimnetic Oxygenation System (HOS) in the Oaks Arm of Clear Lake to improve water quality. By adding oxygen to deep waters, this approach targets the root cause of harmful algal blooms and helps restore a healthier lake.

What’s Happening in the Lake

Low oxygen levels develop in deeper waters in the summer and fall.
Stratification (layering of warm water over cold water) prevents lake mixing
Wind-driven currents move nutrients throughout the lake
Warm, nutrient-rich conditions allow harmful algae to thrive

Why It Matters

Research shows that 70–95% of the lake’s phosphorus that is driving the development of harmful algal blooms comes from within the lake. When oxygen levels drop in deeper waters, phosphorus is released from sediments—fueling harmful algal blooms that threaten public health, wildlife, and recreation.

The Impact

These conditions lead to harmful algal blooms (HABs) that can:

Produce toxins dangerous to people and animals
Damage aquatic ecosystems
Limit safe drinking water and recreation

The Path Forward

The HOS directly addresses low oxygen levels in the lake’s depths (its hypolimnion) - helping to:

Reduce internal phosphorus release
Limit harmful algal blooms
Support long-term lake health

Timeline

UC Davis is working to have the oxygenation system operational in summer - fall 2027, marking a major step toward improving water quality in Clear Lake.

This project builds on years of UC Davis research to deliver a science-based solution for Clear Lake’s future. Since 2018, UC Davis researchers have been part of a multidisciplinary, multi-agency effort to identify the root causes of the challenges Clear Lake is facing. The Blue Ribbon Committee for the Rehabilitation of Clear Lake (BRC), which oversees UC Davis efforts, is focused on developing and providing actionable recommendations to the Governor and the California Legislature to improve Clear Lake's water quality and ecosystem, supporting the surrounding community.