Lake Hennessey - Napa County, California

Visited on 3/24/2018 while Jeff and I along with our two dogs, Summer and Skye took a Saturday drive from our Ranch over to Napa Valley.   Just to the north of the lake is a nice hiking trail that leads up Moore Creek.  We took our dogs for a nice little hike up the trail about ½ mile, we met others on the trail and they have a horse staging area at the parking lot.  Lake Hennessey is a 790 acre reservoir in the Vaca Mountains, a few miles east of St. Helena and the Napa Valley, within Napa County, California.

The reservoir located at an elevation of 322 feet above sea level is formed by Conn Creek Dam, built in 1948 across Conn Creek. Construction of the earthen dam was authorized by the United States Congress when it passed the Flood Control Act of 1944 in order to mitigate flooding downstream in Napa, California.

Funding for the dam was never appropriated by Congress, so in 1946 the City of Napa took on the project and built it at a cost of $550,000 dollars plus $250,000 for the land. The cost of laying the 36 inches diameter pipeline from the dam to the city of Napa was $1.7 million. The 30 miles of pipe for the project was manufactured at the Basalt Rock Company plant located south of city of Napa.  The design of the dam did not include a way to drain water from the reservoir when it comes close to full capacity. Once the lake is full, water drains from a spillway causing potential flooding dangers downstream. The reservoir and pipelines are maintained by the city of Napa, and it is its primary source of water. When the reservoir reaches its capacity, outflow reaches San Pablo Bay via Conn Creek to the Napa River.  The lake was named after Edwin R. Hennessey. Hennessey was a local civic leader who played a role in the development of the Conn Valley reservoir.

Sign at the Boat Launch at Lake Hennessey.  Only small boats, canoes and kayaks allowed on this lake with a maximum speed of 10 mph.

 

Just north of Lake Hennessey we found Moore Creek Park and hiking trail.  We took a nice little 1/2 mile hike along the creek.  We stopped and took a little break on these cool stools made from tree stump pieces.  Great little hike and they have a horse staging area as well.  Napa County maintains and funds this great little gem.