Shadow Cliffs Regional Recreation Area

Last updated
Shadow Cliffs Regional Recreation Area
LocationAlameda County, California
Nearest cityLivermore, California/Pleasanton, California
Area266 acres (1,080,000 m2)
Operated byEast Bay Regional Park District

Shadow Cliffs Regional Recreation Area is a regional park on the border of Pleasanton, California, and Livermore, California that is part of the East Bay Regional Parks (EBRP) system on Stanley Blvd. The lake was once a gravel pit, but then included a sandy beach with swimming, water slides and it supports fishing and recreational boating. Now the water slides have been taken down and is now planned to be replaced by an Interpretive Center. The park is also a popular picnic ground.

A regional park is an area of land preserved on account of its natural beauty, historic interest, recreational use or other reason, and under the administration of a form of local government.

Pleasanton, California City in California, United States

Pleasanton is a city in Alameda County, California, incorporated in 1894. It is a suburb in the San Francisco Bay Area located about 25 miles (40 km) east of Oakland, and 6 miles (9.7 km) west of Livermore. The population was 70,285 at the 2010 census. In 2005 and 2007, Pleasanton was ranked the wealthiest middle-sized city in the United States by the Census Bureau. Pleasanton is home to the headquarters of Safeway, Workday, Ellie Mae, Roche Molecular Diagnostics, Blackhawk Network Holdings, and Veeva Systems. Other major employers include Kaiser Permanente, Oracle, Nordstrom and Macy's. Although Oakland is the Alameda County seat, a few county offices and a courthouse are located in Pleasanton. The Alameda County Fairgrounds are located in Pleasanton, where the county fair is held during the last week of June and the first week of July. Pleasanton Ridge Regional Park is located on the west side of town.

Livermore, California City in California, United States

Livermore is a city in Alameda County, California, in the United States. With an estimated 2017 population of 89,648, Livermore is the most populous city in the Tri-Valley. Livermore is located on the eastern edge of California's San Francisco Bay Area. The incumbent Mayor of Livermore is John Marchand.



Shadow Cliffs, a former gravel quarry, was donated to EBRP by Kaiser Industries, formerly the operator of the quarry, and opened as a park in 1971. The U.S. Bureau of Outdoor Recreation provided a grant of $250,000 for development of park facilities. Thus funded, EBRPD developed a 266 acres (1,080,000 m2) park that included an 80 acres (320,000 m2) lake, picnic facilities and large parking lot. [1]



Swimming is allowed year-round at the swimmer's own risk, even though lifeguards are on duty during the summer. The swimming beach on the main lake and a refreshment stand that are open on weekends in Spring and Fall and daily in summer. Pets and glass containers are not allowed on the sandy areas of the beach. Beach wheelchairs are available at no charge on a first-come, first-served basis. [1]


Fishing is allowed in the main lake, provided the angler has a Park District Daily Fishing Access Permit. Trout and catfish are planted every week by park personnel. Other species popular with anglers are bluegill and black bass. [1]

The California Office of Environmental Health Hazard Assessment (OEHHA) has developed a safe eating advisory for fish caught in the Shadow Cliffs Regional Recreation Area based on levels of mercury or PCBs found in local species. [2]

The Office of Environmental Health Hazard Assessment, commonly referred to as OEHHA, is a specialized department within the cabinet-level California Environmental Protection Agency (CalEPA) with responsibility for evaluating health risks from environmental chemical contaminants.

Polychlorinated biphenyl any chemical compound from a series of congeners based on biphenyl skeleton, differing from other compounds of this group by a number and position of chlorine atoms

A polychlorinated biphenyl (PCB) is an organic chlorine compound with the formula C12H10−xClx. Polychlorinated biphenyls were once widely deployed as dielectric and coolant fluids in electrical apparatus, carbonless copy paper and in heat transfer fluids.

E. coli

Lake water at Shadow Cliffs Beach is tested for bacterial levels weekly during April through October and twice a month from November to March. [3] In July 2014 EBRP closed the lake to swimmers due to extremely high levels of E. coli bacteria. Testing of water samples demonstrated E. coli at 6,100 colonies per 100 milliliters at the lake's south beach and 1,000 colonies per 100 milliliters at the north beach. California's state standard for daily maximum exposure is 235 colonies per 100 milliliters. Hal MacLean, the district water management supervisor, suggested that a combination of drought conditions, low water levels and accumulated animal feces - probably from geese - had caused the high bacterial content. EBRP planned to treat the lake with an oxidizing agent and "direct geese away from the swim area" in an attempt to lower the levels. [4]

<i>Escherichia coli</i> Gram-negative, rod-shaped bacterium

Escherichia coli, also known as E. coli, is a Gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus Escherichia that is commonly found in the lower intestine of warm-blooded organisms (endotherms). Most E. coli strains are harmless, but some serotypes can cause serious food poisoning in their hosts, and are occasionally responsible for product recalls due to food contamination. The harmless strains are part of the normal microbiota of the gut, and can benefit their hosts by producing vitamin K2, and preventing colonization of the intestine with pathogenic bacteria, having a symbiotic relationship. E. coli is expelled into the environment within fecal matter. The bacterium grows massively in fresh fecal matter under aerobic conditions for 3 days, but its numbers decline slowly afterwards.

Oxidizing agent chemical compound used to oxidize another substance in a chemical reaction

In chemistry, an oxidizing agent is a substance that has the ability to oxidize other substances — in other words to cause them to lose electrons. Common oxidizing agents are oxygen, hydrogen peroxide and the halogens.

Quagga mussel inspections

Effective October 1, 2016, EBRPD required that all motorized and paddle boats entering Shadow Cliffs Lake be inspected for quagga mussels. The district will charge owners a $7.00 fee to inspect motorized boats, and $3.00 to inspect inflatables, kayaks, canoes, and other vessels carried on top of cars entering Shadow Cliffs Regional Recreation Area. [5]

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  1. 1 2 3 "Shadow Cliffs Regional Recreation Area." East Bay Regional Park District. Accessed August 14, 2017.
  2. "California Fish Advisory Map". OEHHA. Retrieved 2018-06-13.
  3. "Shadow Cliffs Regional Recreation Area". East Bay Regional Park District . Retrieved July 30, 2014.
  4. Thomas, Jeremy (July 25, 2014). "Harmful Bacteria Prompts Closures for Swimmers at Popular East Bay Lakes". Oakland Tribune . Oakland. Archived from the original on September 24, 2015. Retrieved July 29, 2014 via HighBeam Research.
  5. Cuff, Denis. "Pleasanton lake to require boat inspections for mussels." East Bay Times. September 8, 2016. Accessed September 6, 2017.

Coordinates: 37°40′10″N121°50′22″W / 37.66944°N 121.83944°W / 37.66944; -121.83944