Del Valle Regional Park

Current Water Quality Conditions

Water Quality Notices
Information concerning Blue-Green Algae and other water-quality issues.

Red Tides FAQs from the San Francisco Bay Regional Water Quality Control Board.

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. We routinely monitor many District water resources as related to: recreational water, drinking water, maintenance projects, storm water, wastewater, lakes and creeks. We also respond to water-related emergencies such as accidental sewage releases, oil spills, or other hazardous material incidents.

Alert LevelParksDescription
No Advisory Posted
Del Valle EAST Swim Beach Water Quality Conditions
Caution Advisory Posted
Del Valle WEST Swim Beach Water Quality Conditions
No Advisory Posted
Shadow Cliffs Lake Water Quality Conditions
Caution Advisory Posted
Horseshoe Lake / Niles Swim Beach Water Quality Conditions
Caution Advisory Posted
Shinn Pond at Alameda County Trails Water Quality Conditions
Danger Advisory Posted
Big Break Regional Shoreline Water Quality Conditions
Caution Advisory Posted
Lake Temescal Water Quality Conditions
Water Advisory Posted
Crown Beach Regional Shoreline Water Quality Conditions
Danger Advisory Posted
Lake Anza at Tilden Park Water Quality Conditions
Danger Advisory Posted
Contra Loma Reservoir Water Quality Conditions
  • There is a Danger Advisory for blue-green algae posted at the reservoir at this time. See Blue-Green Algae Information for additional details.
  • Note: The Swim Lagoon is closed for the 2024 season. Blue-Green Algae issues do NOT affect the Contra Loma Swim Lagoon water quality.
Water Advisory Posted
Keller Beach at Miller/Knox Regional Shoreline Water Quality Conditions
No Advisory Posted
Shadow Cliffs Arroyo Water Quality Conditions
  • There are no current advisories for blue-green algae posted at Shadow Cliffs Arroyo. See the Blue-Green Algae Information page for additional details.
Danger Advisory Posted
Lake Chabot Water Quality Conditions
Danger Advisory Posted
Lago Los Osos at Quarry Lakes Park Water Quality Conditions

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. 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

Sign up for Monthly e-Newsletter Updates