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.

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.

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.

An oxygenation device will be tested in the area near where Glen Echo Creek enters the Lake. This device will pump oxygen into the water from the Lake bottom. Towards the Pergola, an aeration device will be tested. This device will churn the water and increase the mixing of air into the water.

The first phase will also produce a three-dimensional hydrodynamic water quality model for Lake Merritt. This model will identify and rank threats to the Lake’s water quality and water quality improvement opportunities. The model will help the City focus on where it can make the most improvements to water quality.

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.

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 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

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