Lake Merritt Water Quality Management Pilot Project

The City of Oakland and partners are working to monitor, understand, and improve Lake Merritt water quality and maintain healthy conditions for fish and wildlife in the Lake. This work is aimed at preventing future fish kills like the one that occurred in August of 2022. This work builds off a legacy of habitat and water quality improvements to the Lake through Measure DD and other City and community efforts.

For March 2024 updates on Lake Merritt water quality and safety guidance, visit this page.

2022 Lake Merritt Fish Kill

In August of 2022 parts of San Francisco Bay suffered the effects of a harmful algal bloom (HAB), from an outbreak of Heterosigma akashiwo, an invasive marine algae associated with red tides. Parts of the Bay turned reddish-brown, and in an abundance of caution, public health warnings were issued to avoid contact with toxins that could be released by the algae. Excessive algae in some places depleted oxygen levels in the water too low for fish to breath. The drop in oxygen levels caused massive fish kills along the California coast and in Lake Merritt, where tens of thousands of dead fish washed up on the shoreline.

For more information about the 2022 HAB as well as a 2023 HAB, click here.

Lake Merritt Water Quality Management Pilot Project

In response to the 2022 Lake Merritt fish kill, the City of Oakland and partners initiated the Lake Merritt Water Quality Management Pilot Project (Pilot). The Pilot is designed to address excessive algae growth and low dissolved oxygen levels associated with the fish kill.

The first phase of the Pilot is underway and includes: continuous monitoring of dissolved oxygen, and other water quality parameters at Lake Merritt, stakeholder engagement, a review of prior water quality data collected by others at Lake Merritt, and the installation of two devices to increase dissolved oxygen in Lake Merritt. The first of these devices, an aeration fountain, was installed August 15, 2023 near the Pergola by El Embarcadero Avenue and replaces an out-of-service fountain at that location. By mixing air into the water, the fountain will improve dissolved oxygen (DO) levels in the Lake, helping to maintain an oxygenated refuge for aquatic life near the fountain. The design and spray settings on the new fountain maximize benefit to wildlife.

An oxygenation device was installed September 27, 2023 and was fully operational October 16, 2023, in the area near where Glen Echo Creek enters the Lake. This device pumps oxygen into the water from the Lake bottom.

Initial planning and monitoring is funded in part through the City’s budget from July 1, 2023- June 30, 2025. Device installation is a project of Oakland’s Capital Improvement Program.

The results of the first phase will inform the scope and need for subsequent work. Oakland’s Capital Improvement Program lists this work as unfunded under the “Lake Merritt Water Quality Management Plan Development and Implementation - Healthy Lake Initiative.” This work will proceed as funding becomes available in future budget cycles and/or through grants.

Success at Lake Merritt will borrow from and inform approaches at other water bodies facing similar threats, threats becoming more common with climate change.

Aeration Fountain installed Aug 15, 2023 at Lake Merritt
Aeration Fountain installed Aug 15, 2023 at Lake Merritt

Lake Merritt Water Quality Data Dashboard


The City of Oakland is grateful for the support and assistance of the following organizations:

  • The Alameda County Flood Control and Water Conservation District
  • The California Department of Fish and Wildlife
  • The East Bay Municipal Utility District
  • The Lake Merritt Institute
  • Laketech
  • The Measure DD Community Coalition
  • Oakland Parks and Recreation Foundation
  • The San Francisco Bay Regional Water Quality Control Board
  • The San Francisco Estuary Project
  • The United States Army Corps of Engineers

Learn more about Lake Merritt, Oakland’s jewel, and the nation’s first wildlife refuge

Fish kill and cleanup August, 2022
Fish kill and cleanup August, 2022