In the 1980s, Lake County's Sanitation District (LACOSAN) found its wastewater systems in need of treatment and disposal upgrades because of growth pressures. At the same time, the region's geothermal industry began to experience productivity declines in the nearby Geysers steam field. Approximately seven percent of California's electricity has been generated at the Geysers since the 1970s, but power plant steam usage was exceeding the steam fields natural recharge rate and steam production was falling. The geothermal heat source remained constant, but injection of additional water was needed to convey the geothermal heat to steam production wells. A survey was conducted from 1990 to 1991 of potential injection water sources available in the region, including surface water, groundwater, and wastewater. That survey concluded that surface and groundwater supplies were already committed to other uses, but that wastewater could achieve two critical objectives at once: first, as a continuous supply of steam field recharge water that could help mitigate Geysers productivity declines; and second, as an effluent disposal method that would be environmentally-superior to conventional surface water discharge or land irrigation methods.
Once the effluent injection concept emerged, the key stakeholders formed a public/private partnership to confirm project feasibility and pursue implementation. This core group included LACOSAN and the main geothermal operators in the southeast portion of the Geysers, including the Northern California Power Agency (NCPA), Calpine Corporation, Unocal Corporation, and Pacific Gas and Electric Company. (Calpine has since acquired Unocal's and PG&E's interests in the Geysers).
Phase 1 groundbreaking for the project was held on October 6, 1995, and following two years of construction, the pipeline was formally dedicated on October 16, 1997. The total construction cost was $45 million, including $37 million for the pipeline and $8 million for wastewater system improvements. Construction costs were shared by the core participants, known as the Joint Operating Committee (JOC), with additional funding from the California Energy Commission, California Water Resources Control Board, U.S. Department of Energy, U.S. Department of Commerce, U.S. Department of the Interior, and U.S. Environmental Protection Agency. Additionally, the geothermal industry partners invested several million dollars in secondary pipelines to distribute the effluent from the main pipeline to injection wells in the Geyser steam field.
Phase 2 of the project began in 1999 with the extension of the pipeline from LACOSAN's Southeast Treatment Plant to the Clearlake Oaks' treatment plant at a cost of approximately $1 million. The Oaks treatment plant is operated by the Clearlake Oaks County Water District, which shared construction costs with the California Water Resources Control Board and LACOSAN. Phase 2 proceeded in 2000 with the construction of the project's first wetland at Lyons Creek near Lakeport. This 22-acre facility contains four wetland cells and a system of interpretive trails and signage for wildlife viewing and education. The Lyons Creek construction cost of $600,000 was shared by LACOSAN and U.S. EPA. The 20-mile Phase 2 pipeline was finished in early 2003 at a total cost of approximately $30 million, which was shared again by the system's co-funding partners.
The JOC members have entered into a 25-year operating agreement wherein LACOSAN operates the pipeline as far as the Middletown Wastewater Treatment Plant/Bear Canyon "0" Pump Station, after which it is industry-operated to its terminus in the southeast Geysers steam field. LACOSAN pays an annual operation and maintenance (O&M) cost share equivalent to conventional effluent disposal, and the industry partners pay the remaining O&M costs based on the quantity of effluent they each receive at their injection wellheads. LACOSAN is responsible for operating the project's wetlands at the NW facility.