City of Oakland Moves Forward with Lake Merritt Healthy Lake Initiative

Lake Merritt is the focus of a new City of Oakland effort to better understand and address water-quality problems, including excessive algae growth and low dissolved oxygen levels that can threaten fish and other aquatic life.

The City’s water-quality work began with harmful algal bloom planning in 2022. Since then, the City has worked with the Lake Merritt Institute, consultants, lake users, advocates, and local experts. The City has also installed equipment designed to increase oxygen levels in areas of the lake where oxygen can become critically low.

In January 2026, the City replaced a hypolimnetic oxygenation system with a diffused aeration system. The City continues to evaluate how oxygenation and other approaches can improve conditions in the lake. It has also obtained a permit allowing the use of a hydrogen peroxide solution during an emergency harmful algal bloom, although the City reports that this treatment has not yet been needed.

The next phase is the Lake Merritt Healthy Lake Initiative, supported by $959,757 in congressionally directed funding. Implementation is expected to begin in fall 2026. The project is intended to develop additional strategies to address excessive algae growth and low dissolved oxygen while protecting aquatic life and reducing the risk of future fish kills.

The initiative will focus on three main areas. First, the City will develop and implement a monitoring plan and evaluate monitoring results and other available data. Second, the City is considering a study to determine the dissolved oxygen levels needed to support aquatic life in Lake Merritt. Finally, the City will evaluate potential ways to manage dissolved oxygen and, if recommended and feasible, install aeration, oxygenation, or other management systems. The effectiveness of any installation will then be evaluated.

The overall goal is to move toward a science-based, long-term approach to managing Lake Merritt’s water quality. By better understanding the lake’s conditions, determining the needs of its aquatic life, and evaluating which management strategies are effective, the City hopes to improve the health of the lake and better protect the fish, wildlife, and community that depend on it.