Lake Hennessey facts for kids
Quick facts for kids Lake Hennessey |
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 Lake Hennessey
Location in California
Lake Hennessey
Location in the United States
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| Location | Vaca Mountains, Napa County, California |
| Coordinates | 38°28′52″N 122°22′24″W / 38.48111°N 122.37333°W |
| Type | Reservoir |
| Primary inflows | Sage Creek, Chiles Creek, Moore Creek, Conn Creek |
| Primary outflows | Conn Creek |
| Catchment area | 54 sq mi (140 km2) |
| Basin countries | United States |
| Max. length | 2 mi (3.2 km) |
| Max. width | 3,500 ft (1,100 m) |
| Surface area | 790 acres (320 ha) |
| Water volume | 31,000 acre-feet (38,000,000 m3) |
| Surface elevation | 322 feet (98 m) |
Lake Hennessey is a large reservoir (an artificial lake) located in the Vaca Mountains in Napa County, California. It sits east of St. Helena and the famous Napa Valley.
This lake was created by building the Conn Creek Dam in 1948. The dam was built across Conn Creek. Its main purpose was to help control floods in the city of Napa, which is downstream.
Building the Dam
The idea for the dam started with the United States Congress. They passed a law in 1944 to help prevent floods. However, Congress did not provide money for the dam.
So, in 1946, the City of Napa decided to build the dam themselves. It cost about $550,000 for the dam itself. They also spent $250,000 to buy the land.
Water Pipeline
After the dam was built, a large pipeline was needed. This pipe would carry water from the dam to the city of Napa. The pipeline was 36 inches wide and about 30 miles long.
Building this pipeline cost $1.7 million. The pipes were made by the Basalt Rock Company, located south of Napa.
How the Lake Works
Lake Hennessey is the main source of drinking water for the city of Napa. The city also takes care of the lake and its pipelines.
When the lake gets very full, water flows out through a special overflow area called a spillway. This water then travels through Conn Creek to the Napa River. Eventually, it reaches San Pablo Bay.
The lake was named after Edwin R. Hennessey. He was an important local leader who helped make the reservoir project happen.
Conn Creek Dam Details
The Conn Creek Dam is an earthen dam. This means it is made mostly of soil and rock.
The dam is about 125 feet high. It stretches for 700 feet across the creek. The top of the dam is 330 feet above sea level. The City of Napa owns and manages this important dam.
