About the Project

Launched in summer 2025, the Lake Elizabeth Water Quality Improvement Pilot Project aims to protect local wildlife and strengthen the lake’s resilience against extreme heat.

The project—costing approximately $175,000—was approved by the Fremont City Council in March 2025 following a fish die-off event that occurred in Lake Elizabeth in July 2024. Expert analysis determined that the cause was a combination of shallow lake depth and extreme heat, which led to a drop in oxygen levels. To help prevent this from occurring in the future, the City implemented the following measures to stabilize water temperatures and maintain healthy oxygen levels in the lake.

• Nine vegetated floating islands: These provide vital shaded shelters for fish and create new habitats for both aquatic and land-based organisms.
• Fountain and two aerators: This equipment helps stabilize water temperatures, keeps the water oxygenated, and improves water circulation to prevent algae growth.
• Three monitoring probes: Thee probes collect real-time data on how effective the measures are in keeping the lake’s temperature and oxygen levels stable.

To date, the project has been well received by the community. We’re excited to share the following updates as of February 2026.

• Thriving habitats: After overcoming early challenges with plant die-offs and pelicans using them as resting spots, the floating islands have successfully taken root. They are now flourishing above the surface, while fish have started to gather in the protected havens below.
• Ongoing maintenance: City staff has gained valuable hands-on experience with the maintenance required to keep these measures running efficiently, providing a better understanding of what is needed to ensure the project’s success.
• Data collection: While we’re still waiting for a major heat event to fully test the measures, they’re all functioning as intended. We’ll continue monitoring the data and providing updates.
• Future planning: The insights gained from this pilot project are being used to develop a comprehensive lake management plan. This future roadmap will explore expanding successful measures to other areas of the lake, incorporating shoreline plantings, and introducing additional protection measures. City staff is currently defining the scope for this expanded effort.

With these measures, our goal is for Lake Elizabeth to remain a healthy haven for wildlife and a place our community can enjoy for years to come. We'll continue to provide updates on how the measures are working.

Lake Elizabeth, an 83-acre freshwater lake within Fremont’s Central Park, serves an important dual purpose: it’s designed for flood control and stormwater storage, and it’s also a beloved recreational hub for our community. The lake is owned by the Alameda County Flood Control and Water Conservation District (ACFCD) and licensed to the City.

Timeline

The project was completed in summer 2025.