Water Use
Desalination and Water Supply Projects
Desalination is the process by which salts are removed from salty or brackish water sources. It is also known as desalting or commonly referred to as “desal.” Monterey Bay National Marine Sanctuary and NOAA Fisheries, with other state and local agencies, developed guidelines (PDF 624 KB) in 2010 to address issues associated with desalination including site selection, construction and operational impacts, plant discharges, and intake systems. The non-regulatory guidelines are intended to assist regulatory agencies in reviewing proposed desalination projects and to help ensure that project proponents and designers address resource protection concerns.
In a separate effort, sanctuary staff partnered with the Association of Monterey Bay Area Governments in identifying the potential environmental, economic, and social impacts, both positive and negative, associated with seawater desalination if conducted in the Monterey Bay area. The 2010 guidelines were developed to specifically address the potential impacts that were identified during an initial 2006 Desalination Feasibility Study for the Monterey Bay Region (PDF 3 MB).
Three sanctuary regulations relate directly to desalination:
- A prohibition on discharging or depositing any material within sanctuary boundaries. Since the brine effluent, and in some cases other materials, are usually disposed of in ocean waters, this activity requires sanctuary authorization of a Regional Water Quality Control Board National Pollutant Discharge Elimination System permit.
- A prohibition on discharging or depositing any material outside of the boundaries, which subsequently enter sanctuary waters and negatively impact resources. This activity requires sanctuary authorization of a Regional Water Quality Control Board National Pollutant Discharge Elimination System permit.
- A prohibition on activities that cause alteration of the seabed. Thus, installation of certain desalination facility structures such as an intake/outfall pipeline on or beneath the ocean floor, will also require sanctuary authorization.
There are currently two desalination facilities adjacent to the sanctuary. One is in Sand City and operated by California American Water. It does not discharge into sanctuary waters and therefore is not permitted by Monterey Bay National Marine Sanctuary. The second is a small desalination plant at the Monterey Bay Aquarium that is permitted by Monterey Bay National Marine Sanctuary through Authorization of the Central Coast Regional Water Quality Control Board’s General National Pollutant Discharge Elimination System Permit for Aquaculture Facilities and Aquariums.
Proposed Water Use Projects Within Monterey Bay National Marine Sanctuary
Pure Water Monterey Groundwater Replenishment Project: #MBNMS-2018-042
Monterey One Water (M1W), in partnership with the Monterey Peninsula Water Management District, designed and built the Pure Water Monterey Project. The Pure Water Monterey Project includes an Advanced Water Purification Facility consisting of a four-step process that would further treat water that has already been treated by the existing primary and secondary treatment processes at the treatment plant. The Pure Water Monterey Project also includes product water conveyance pipelines, pump station, and injection well facilities.
The project is located in the unincorporated area of Monterey County, and within the cities of Salinas, Marina, and Seaside, and collects source water (agricultural wash water, urban stormwater runoff, and surface waters) and combines them with existing wastewater inflow to the treatment plant to receive primary and secondary treatment before beneficial reuse at either the Salinas Valley Reclamation Plant or by the Pure Water Monterey Project Advanced Water Purification Facility.
The Pure Water Monterey Project is designed to create a reliable supply of water for Monterey County by replenishing the Seaside Groundwater Basin with 3,500 acre feet per year of purified recycled water. This replaces a portion of CalAm’s water supply as required by State Water Resources Control Board (State Water Board) orders and provides up to 600 acre feet per year of purified recycled water to Marina Coast Water District for urban landscape irrigation.
Monterey Peninsula Water Supply Project: #NOAA-NOS-2016-0156
The Monterey Peninsula Water Supply Project is a full scale desalination plant proposed to be located in Marina, California. Monterey Bay National Marine Sanctuary was designated as the federal lead for National Environment Policy Act review and worked with the California Public Utilities Commission to develop a joint Environmental Impact Statement/Environmental Impact Report.
The purpose of the Monterey Peninsula Water Supply Project is to replace existing water supplies for CalAm’s Monterey District service area. The proposed project comprises various facilities and improvements, including: a subsurface seawater intake system; a 4.8-million gallons per day seawater reverse osmosis desalination plant; desalinated water storage and conveyance facilities; and expanded aquifer storage and recovery facilities. The desalination facility would be capable of producing 4.8-million gallons per day of potable water on a 46-acre site located north of the city of Marina on unincorporated Monterey County property. The Monterey Peninsula Water Supply Project proposes five subsurface slant wells (four new wells and conversion of an existing test well) to draw seawater from beneath the ocean floor in Monterey Bay to produce the source water for the desalination plant. The subsurface slant wells would be located primarily within the city of Marina, in the former mining area of the CEMEX sand mining facility. The slant wells would be approximately 1,200 feet in length and extend beneath the coastal dunes, sandy beach, and the surf zone, terminating seaward of the mean high water line and at a depth of 190 to 210 feet below the seafloor. The brine would be discharged into Monterey Bay via a 36-inch diameter pipeline to a new connection with the existing Monterey One Water’s outfall and diffuser located offshore.
California American Water Slant Test Well Project: #NOAA-NOS-2014-0078
The purpose of the California American Water Slant Test Well Project is to develop slant test wells, which would extend into submerged lands of Monterey Bay National Marine Sanctuary through the Dune Sand Aquifer, Salinas Valley Aquitard, and 180-Foot Aquifer or its equivalent unit at this location. The slant test well is proposed for information gathering purposes. It will operate as a test facility for a temporary period (maximum 24-month pumping period) to provide field data concerning the geologic, hydrogeologic, and water quality characteristics of the project site. The overall project, including construction and decommissioning activities, is expected to take no longer than 3 years. The data obtained through operation of the proposed project would be used in the design and planning of a potential subsurface intake system and desalination plant that has been proposed to serve as the primary future water supply source for the Monterey Peninsula known as the Monterey Peninsula Water Supply Project.