Monterey One Water
Formerly known as the Monterey Regional Water Pollution Control Agency (MRWPCA), Monterey One Water was established in 1979 to administer water rationing in response to severe drought conditions . MRWPCA was formed under a Joint Powers Authority agreement between the City of Monterey, the City of Pacific Grove and the Seaside County Sanitation District as a peninsula-wide effort to resolve area’s water issues . MRWPCA operates the Regional Treatment Plant, the Salinas River Diversion Facility, the Castroville Seawater Intrusion Project, sewage collection pipelines, and 25 wastewater pump stations .
Monterey One Water, formerly known as the Monterey Regional Water Pollution Control Agency (MRWPCA), was established in November, 1972, as a joint effort between the Monterey, Pacific Grove, and Seaside Sanitation districts. They joined together to provide the water treatment standards set in place by the Federal Clean Water Act. Before the establishment of Monterey One Water, each individual community was responsible for the management of their own wastewater, which was often discharged discharge directly into the bay.
In addition to meeting the water quality standards outlined in the Clean Water Act, Monterey One Water was responsible addressing the region deteriorating groundwater supply. By the mid-1970s, excessive groundwater pumping for agricultural purposes resulted in an overdraft of the underlying aquifer, exacerbating the effects of saltwater intrusion. The continued encroachment of saltwater (Salinas Valley Seawater Intrusion) into the Salinas Valley Groundwater Basin began to pose a serious threat to the regions multi-billion dollar agricultural industry, as well as limiting the drinking water supply for the City of Salinas. Community leaders began discussing possible solutions to address the growing concerns of saltwater intrusion, eventually deciding on the use of recycled wastewater to supplement crop irrigation, reducing the need to deplete groundwater reserves. After an extensive 11-year study the Monterey Wastewater Reclamation Study for Agriculture final report was released on April 3rd, 1987. This document outline the feasibility of using reclaimed water for agricultural irrigation and address concerns about potential heath impacts associated with consuming crops grown with recycled water.
In 1983, Monterey One Water was ready to implement its plan of an unified sanitation district. This process included the construction of a wastewater conveyance system that utilized neighboring treatment plant stations to distribute wastewater to one centralized facility. These treatment plants were decommissioned in February, 1990, after the new 29.6 Million Gallon per Day (MGD) Regional Treatment Plant began operation.
As of 2018, Monterey One Water is responsible for operating and maintaining 25 pump stations, 35 pressure-vacuum stations, and approximately 750 miles of pipeline and the Regional Treatment Plant treats and distributes 18.5 MGD for agricultural and domestic use. 
Projects and Facilities
- Pure Water Monterey
- Castroville Seawater Intrusion Project
- Salinas River Diversion Facility
- Regional Treatment Plant
- Monterey One Water Homepage
- Monterey One Water, 2017. About: History. http://montereyonewater.org/about_history.html
- Monterey Wastewater Reclamation Study for Agriculture http://montereyonewater.org/docs/about/mwrsa.pdf
- Monterey One Water, 2017. Wastewater Conveyance. http://montereyonewater.org/facilities_conveyance.html
- Monterey One Water Homepage
- Monterey Peninsula Groundwater Replenishment Project
- Salinas Valley Seawater Intrusion
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