Kelseyville Wastewater Treatment


The Kelseyville wastewater collection and treatment facility was constructed in the late 1960’s. The collection system serves the downtown and surrounding residential areas of Kelseyville. Wastewater from the Clear Lake State Park was added during the 1970’s and the wastewater collection system of Corinthian Bay (AD 9-2) was added in the 1980’s.

Raw wastewater is conveyed through the collection system and treated at the Gaddy Lane treatment facility and pumped to the evaporation percolation ponds facility on Mt. Konocti for final disposal.

Customer Statistics and Infrastructure

The Kelseyville Wastewater Collection and Treatment System currently includes:

    • Kelseyville: 859 service connections (1,374 Single Family Dwelling (SFD) equivalents)
    • Corinthian Bay (AD 9-2): 72 service connections (73 SFDs)
    • Clear Lake State Park: Metered flow (typically equivalent to 16 SFDs)
    • 179 manholes (160-Kelseyville, 15-Corinthian, 4-State Park) and over 15 miles of pipe within the gravity collection system.
    • 6 lift stations (4-Kelseyville, 1-Corinthian, and 1-State Park) and over 4 miles of force main piping conveying wastewater flows to the Kelseyville Treatment Plant (Gaddy Lane). Two pumps convey the treated effluent from the Gaddy Lane facility to the evaporation ponds on Mt. Konocti.


The Kelseyville facility was originally constructed 40 years ago for a much smaller community. Over the years, the number of customers grew and by 2009, the treatment plant and facilities were operating at, or near capacity. The 12-month averaged increase (2008) in the Kelseyville customer base is 1.8%. In 2010, the District expanded the treatment facility through the conversion to an aerated lagoon process.
In 2009, improvements at the treatment plant were completed to increase treatment capacity. The Blue Frog Technology for biological sludge removal was installed on the fall of 2015.


The final stages of expansion including the addition of the second half of a new force main to the storage and disposal/reuse facilities is the primary focus within the system. Disposal capacity at the percolation-evaporation ponds will need to be increased in the in the near future.

Besides the expansion efforts, the District is moving forward toward the development of a Network Hydraulic Model for the collection system. The hydraulic model will provide staff a tool to better evaluate structure, capacity and flows within the collection system. It  will also identify the areas within the collection system where infrastructure improvements are necessary in response to planned community growth.

Treatment Plant: Kelseyville
Type: Rich Aerated Lagoon process
Connections: 1,360

Collection area: Kelseyville (KCWWD #3)
Connections: 854
Population: 1,374

Collection area: Corinthian Bay (AD 9-2)
Connections: 72
Population: 188

Collection area: State Park
Connections: 16 (3,360 gpd)
Population: 48