Shadow Cliffs’ Swim Beach Opens. Lake Temescal's Swim Beach Remains Closed


 On Saturday, August 30th the Lake Temescal swimming area reopened to the public and it will remain open through October, or until further notice. However, lifeguard services are no longer available, so swimming is at your own risk. Water quality monitoring continues at both Lake Temescal and Shadow Cliffs. 

July 29, 2014

Water testing resumed on Monday, July 28th at Lake Temescal and Shadow Cliffs swim areas to monitor the levels of two types of water quality indicator organisms found in the water at both popular swim lakes. 

Also today, the Park District is working together with the Alameda County Environmental Health Department to apply PAK 27, a safe, organic and biodegradable algaecide, to both lakes. The District received approval to apply this product late last week. The treatment breaks down cell walls destroying algae and bacteria and helps prevent the release of toxins from blue-green algae. The product’s active ingredients are Hydrogen Peroxide and Peroxy Acetic Acid, which biodegrade completely into water and oxygen. Waters treated with PAK 27 can be used during and after application for swimming, fishing, and drinking water supply.

Lake Temescal’s swim beach has been closed since July 18th because of an unusually high level of the toxin microcystin found in blue-green algae, a native aquatic plant that reacts, in part, to nutrients, sunlight and temperature. Typically the blooms, or buildup of the algae, last for a few days, but they have lasted much longer this summer. This is a rare occurrence that the District staff has been monitoring closely. Visual observations of the lake appear to indicate that the blue-green algae bloom is dissipating. However, the District must verify that the levels of the microsytin toxin have been reduced to acceptable levels before the lake can reopen.

Last Friday, Shadow Cliffs closed due to high levels of E. coli bacteria in the lake, brought on by drought conditions that are impacting lake levels and the abundance of geese and other wildlife that are populating the water. Park District Water Resources staff has been working with Alameda County Environmental Health labs to track the levels of bacteria. The bacteria count dropped over the weekend due in part to fencing installed by the Park District to keep geese from swimming and congregating on the beach at the water’s edge.

Water quality testing on Monday July 28th determined that indicator bacteria levels at Shadow Cliffs had significantly improved, and the lake will be reopened to swimming on Wednesday July 30th.

The Park District encourages all visitors who want to enjoy water activities to visit these other popular lakes, beaches, and swim lagoons:

Lake Anza at Tilden Regional Park in Berkeley, Cull Canyon at Castro Valley, Contra Loma Lagoon in Antioch, Don Castro in Hayward, Quarry Lakes in Fremont,  Del Valle Recreation Area in Livermore,  Crown Beach in Alameda, and Roberts Pool at Roberts Regional Recreation Area in Oakland.

The East Bay Regional Park District is a system of beautiful public parks and trails in Alameda and Contra Costa counties east of San Francisco Bay, established in 1934. The system comprises 114,000+ acres in 65 parks including over 1,200 miles of trails for hiking, biking, horseback riding and nature learning.

Carolyn Jones
(510) 544-2003