|Shadow Cliffs Regional Recreation Area|
|Location||Alameda County, California|
|Nearest city||Livermore, California/Pleasanton, California|
|Area||266 acres (1,080,000 m2)|
|Operated by||East 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.
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.
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.
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.
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.
Lake water at Shadow Cliffs Beach is tested for bacterial levels weekly during April through October and twice a month from November to March. 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.
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.
- "Shadow Cliffs Regional Recreation Area." East Bay Regional Park District. Accessed August 14, 2017.
- "California Fish Advisory Map". OEHHA. Retrieved 2018-06-13.
- "Shadow Cliffs Regional Recreation Area". East Bay Regional Park District . Retrieved July 30, 2014.
- 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.
- Cuff, Denis. "Pleasanton lake to require boat inspections for mussels." East Bay Times. September 8, 2016. Accessed September 6, 2017.