Pacheco Reservoir

Pacheco Lake
Location Diablo Range, eastern Santa Clara County, California
Coordinates 37°03′41″N 121°17′41″W / 37.06139°N 121.29472°W / 37.06139; -121.29472[1]Coordinates: 37°03′41″N 121°17′41″W / 37.06139°N 121.29472°W / 37.06139; -121.29472[1]
Type Reservoir
Primary outflows North Fork Pacheco Creek[2]
Catchment area 67.2 sq mi (174 km2)[2]
Basin countries United States
Max. length 2 miles (3.2 km)
Max. width 1,500 feet (460 m)
Surface area 197 acres (80 ha)[2]
Water volume 6,150 acre feet (7,590,000 m3)[2]
Surface elevation 476 feet (145 m)[1]

Pacheco Reservoir is an artifical lake or reservoir in the Diablo Range in San Benito County, California, U.S.A. formed by a dam on the north fork of Pacheco Creek. Located north of State Route 152 in eastern Santa Clara County, the lake is about an hour's drive from downtown San Jose.

The lake is formed by a dam across the north fork of Pacheco Creek, whose waters reach Monterey Bay by way of the Pajaro River.

North Fork Dam

North Fork Dam
Country United States
Location Santa Clara County, California
Coordinates 37°3′1″N 121°17′29″W / 37.05028°N 121.29139°W / 37.05028; -121.29139
Opening date 1939[2]
Owner(s) Pacheco Pass Water District[2]
Dam and spillways
Type of dam Earthen[2]
Impounds Pacheco Creek[2]
Height 100 feet (30 m)[2]
Length 600 feet (180 m)[2]
Elevation at crest 483 feet (147 m)[2]
Width (crest) 20 feet (6.1 m)[2]
Dam volume 325,000 cubic yards (248,000 m3)[2]
Reservoir
Creates Pacheco Lake
Total capacity 6,150 acre feet (7,590,000 m3)[2]
Catchment area 67.2 square miles (174 km2)[2]
Surface area 197 acres (80 ha)[2]
Max. length 2 miles (3.2 km)
Max. width 1,500 feet (460 m)
Normal elevation 476 feet (145 m)[1]

The lake's waters are impounded by the North Fork Dam, an earthen dam built in 1939. The dam is 100 feet (30 m) high and 600 feet (180 m) long and contains 325,000 cubic yards (248,000 m3) of material. Its crest is 483 feet (147 m) above mean sea level.[2]

The reservoir dam is an impassable barrier to in-migrating steelhead trout (Oncorhynchus mykiss), preventing access to the nearly 34.5 miles (55.5 km) of stream consisting of North Fork Pacheco Creek, Mississippi Creek and East Fork Pacheco Creek.[3] Resident rainbow (the landlocked form of steelhead) trout successfully rear in fast-water habitats above the dam. They grow rapidly and reach smolt size by the end of their first summer. In many years in late spring, prior to reservoir releases for agriculture, low stream flows and high water temperatures severely impact steelhead fry and small juveniles.[4]

See also

References

  1. 1 2 3 4 "Pacheco Lake". Geographic Names Information System. United States Geological Survey.
  2. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 "Dams Within the Jurisdiction of the State of California (N-S)" (PDF). California Department of Water Resources. Retrieved September 29, 2012.
  3. ↑ U.S. Geological Survey. National Hydrography Dataset high-resolution flowline data. The National Map, accessed February 6, 2016
  4. ↑ Jerry Smith (2007). Effects of Operation of Pacheco Reservoir on Steelhead (Report). San Jose State University. Retrieved 2016-02-06.
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