Del Valle Regional Park

Water Quality

Water Quality Notices
Information concerning cyanobacteria (blue-green algae) and other water-quality issues.

The Water Management Department's objective is to enhance District natural resources and to comply with local, state and federal water quality standards intended to protect public health, safety, and the environment. To achieve this, Water Management staff routinely monitors many District water resources as related to: recreational water, drinking water, maintenance projects, storm water, wastewater, lakes and creeks. Water Management also responds to water-related emergencies such as accidental sewage releases, oil spills, or other hazardous material incidents.

Alert LevelParksDescription
Danger Advisory Posted
Water Quality Notice

Cyanobacteria (blue-green algae) is present in the reservoir and a Danger Advisory posted. No swimming is allowed. See Cyanobacteria (Blue-Green Algae) Updates for more information. Conditions [PDF]

Water Warnings Posted
Water Quality Notice

Cyanobacteria (blue-green algae) is present at Horseshoe Lake, but no toxins have been detected. There are no advisories posted at Horseshoe Lake or the swim beach this time. See Cyanobacteria (Blue-Green Algae) Updates for more info.
Conditions [PDF] |  Monitoring Program | Cyanobacteria (Blue-Green Algae) Updates

Water Warnings Posted
Water Quality Notice

Cyanobacteria (blue-green algae) is present at the lake, but no toxins have been detected recently. There are no advisories posted at this time. See Cyanobacteria (Blue-Green Algae) Updates for more info.
Monitoring Program | Cyanobacteria (Blue-Green Algae) Updates
The District regularly monitors Lake Temescal to ensure the water quality meets acceptable levels for fishing and swimming.  Water quality samples are taken from four locations around the Lake; including the swim beach.

The Swim Facility/Area is CLOSED until further notice.

Water Warnings Posted

Lake Anza Swim Area: CLOSED - No Swimming. Cyanobacteria (blue-green algae) is present in lake, but no toxins have been detected recently. There are no advisories posted at the lake. As a precaution, keep dogs away from water.
Lake Anza Lawn Area: CLOSED, until further notice, for a construction project. Please use alternative lawn areas at the Brazil Room and at Meadows on Lone Oak Rd. Restrooms at lake facility closed with portable restrooms available in the parking lot during the project. The Lake Anza Trail and picnic sites are open for use. 

Water Quality Notice
Water Conditions [PDF] | Monitoring Program | Cyanobacteria (Blue-Green Algae) Updates

Caution Advisory Posted
Water Quality Notice

Cyanobacteria (blue-green algae) is present at the lake and toxins have been detected recently. A Caution Advisory is posted around the lake.
See Cyanobacteria (Blue-Green Algae) Updates for more information.

Water Warnings Posted
Water Quality Notice

Shadow Cliffs swimming is CLOSED for the 2021 season due to low water levels. There are no cyanobacteria advisories at this time.
Cyanobacteria (Blue-Green Algae) Updates

Water Warnings Posted
Water Quality Notice

Keller Beach is OPEN for swimming.
Conditions [PDF] 

Water Warnings Posted
Water Quality Conditions

Crown Beach is OPEN for swimming

Conditions [PDF]

Caution Advisory Posted
Remedial Action Notice

The Leona Heights Rifle Range within Leona Canyon is under a surveying and clean-up action plan that will be performed by the U.S. Army National Guard and Army Corps of Engineers. The site was once used as a military rifle range prior to acquisition by the Park District. The Rifle Range is located along Keller Avenue and Campus Drive in the Sequoyah Heights neighborhood. Map | Fact Sheet

Please direct all questions to:
Reuben Sendejas
, CA Army National Guard

Caution Advisory Posted
Water Quality Notice - Shinn Pond

Cyanobacteria (blue-green algae) is present and a Caution Advisory is posted at Shinn Pond. Swimming is never allowed and water contact is currently not permitted at Shinn Pond. Due to the presence of toxic algae in the pond, please keep dogs away from the water. Cyanobacteria (Blue-Green Algae) Updates

Swim Beach Water Quality Monitoring Program Map


Water Quality Program

The East Bay Regional Park District's goal is to protect public health by monitoring swim beaches. The District's pool facilities are treated with chlorine to control potentially harmful bacteria that may be present in the water. In natural, un-chlorinated water bodies (Examples: ponds, lakes, and San Francisco Bay), bacteria levels can change frequently, so Water Management collects samples on a weekly basis from April to October to evaluate water quality conditions at public swim areas. Using the California Department of Public Health's "Draft Guidance for Salt Water Beaches and Draft Guidance for Fresh Water Beaches", East Bay Parks collaborates with both Contra Costa and Alameda County Departments of Environmental Health to inform the public about current conditions and safe recreation choices. We regularly post up-to-date data and information on water quality at natural swim areas.

Thousands of bacteria can be present in un-chlorinated swim water at any time, some more harmful to human health than others. It is not possible to test water samples for all types of harmful bacteria, so health professionals focus on a few "indicator" bacteria that are typically found with harmful bacteria. In California, water quality agencies use four indicator bacteria categories: the total number of coliform bacteria colonies per sample, fecal coliform bacteria, Enterococcus and E. coli. If bacteria levels at swim areas exceed state standards for these bacteria, swimming could pose increased risks to human health.

Signs at swim areas represent current water quality conditions with a traffic signal. A green light indicates that our indicator bacteria test results are below the maximum levels and meet State standards. A yellow light indicates that one or more of any of the indicator bacteria at that location is above the daily maximum level and exceeds State standards. A red light means that the beach is closed due to a water quality issue. The current cyanobacteria (blue-green algae) conditions will influence the sign as well. For your safety and the safety of others, do not enter the water if the beach is closed.
Swim Beach Data will remain posted at our fresh water lakes along with these traffic signal signs for your information and convenience.

To have a fun and safe experience swimming in the parks, we encourage you to follow a few simple rules:

  • Do not swim in lakes or the SF Bay for 3 days after a rainstorm
  • Pay attention to the lifeguards and water quality information
  • After you leave the water, shower and towel dry as soon as possible
  • Keep lake and bay water out of your mouth
  • All Park District Swim Facilities

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