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Santa Margarita Groundwater Basin

The Santa Margarita Groundwater Basin (SMGB) is a primary source of water supply for Scotts Valley, San Lorenzo Valley, and Santa Cruz. It covers over 30 square miles in the Santa Cruz Mountains foothill forming a triangular area that extends from Scotts Valley to the east, Boulder Creek to the northwest and Felton to the southwest.

The major water purveyors that directly rely on the supply from SMGB are Scotts Valley Water District (SVWD), San Lorenzo Valley Water District (SLVWD), and Mount Hermon Association (MHA). SMGB is also the sole supply source for 13 small water systems and over 1,100 private well users. In addition, the City of Santa Cruz derives a major portion of its supply from San Lorenzo River watershed that overlaps the basin.

The decline of groundwater levels in many parts of the basin occurred during 1985-2004 representing a loss in groundwater storage in SMGB by an estimated 28,000 acre-feet resulting in diminished local water supply and reduced sustaining base flows to local streams that support fishery habitats. Due to the conservation and other management efforts at local water agencies, the total extraction from SMGB has decreased 45% since 1997 and for the last 10 years, the demand and supply in the basin have been in balance.

SVWD has actively managed groundwater in the area since the early 1980s in an effort to increase water supply reliability and to protect local water supply sources. In 1983, SVWD instituted a Water Resources Management Plan to monitor and manage water resources, in 1994 the agency formally adopted a Groundwater Management Plan in accordance with AB3030, also known as the Groundwater Management Act under Water Code section 10750.

In 1995, SVWD, SLVWD, MHA, Lompico County Water District, City of Scotts Valley and County of Santa Cruz signed a Memorandum of Understanding forming Santa Margarita Groundwater Basin Advisory Committee that was actively involved in the cooperative groundwater management of the basin until its dissolution and substitution with Santa Margarita Groundwater Agency (SMGWA) in 2017.

SMGWA is a Groundwater Sustainability Agency (GSA) that was formed as a Joint Powers Authority in June 2017. It has three member-agencies: Scotts Valley Water District, San Lorenzo Valley Water District, and County of Santa Cruz and is governed by the Board of Directors comprising of two representatives from each member agency, one representative from City of Scotts Valley, one from City of Santa Cruz, one from Mount Hermon Association and two private well owner representatives. The Board of Directors holds monthly meetings that are open to the public. The staffing support and funding for the agency is provided by the member agencies. More information is available at www.smgwa.org.

To learn more about the Santa Margarita Basin, please visit our Groundwater page.