Santa Margarita Groundwater Agency (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 (SVWD), San Lorenzo Valley Water District (SLVWD), and the County of Santa Cruz (County) 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 (MHA) 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 agency.
Under the Sustainable Groundwater Management Act of 2014, overdrafted groundwater basins need to be sustainably managed by a GSA through the development of a Groundwater Sustainability Plan (GSP). The GSP must be completed by 2022, and the basin must reach sustainability by 2042.
Groundwater is the primary source of drinking water for residents living in the Santa Margarita Groundwater Basin (SMGB) boundary. Groundwater is also important to stream base flow in the summer months. Rainfall is the only source of recharge to the basin. The groundwater basin is shared by users including SVWD, SLVWD, MHA, as well as local businesses and residents using private wells. To that end, SVWD, SLVWD, and County recognize that sustainable groundwater management is essential and ensure reliable and resilient water systems and desire to continue to work collectively on the implementation of SGMA.
The Basin is made up of the Santa Margarita Sandstone, Monterey shale and the Lompico and Butano formations. The basin is now in a state of overdraft due to decades of overpumping — taking water out at a higher rate than it can be recharged to the basin. Groundwater levels are now approximately 200 feet below their natural levels. While these levels are no longer decreasing, recovery is still a long way out. Low groundwater levels mean less water in the streams for fish and wildlife, and less water security for people. SVWD prepares annual reports that focus on groundwater conditions and system operations in the Scotts Valley area of the Santa Margarita Basin.
Previously DWR Bulletin 118 (DWR 2003) did not identify SMGB as a groundwater basin but rather recognized three smaller basins in the vicinity: Scotts Valley Basin, Felton Area Basin, and Santa Cruz Purisima Formation. These basins did not accurately reflect the groundwater supply resources supporting the North Santa Cruz County communities. SVWD with support from SLVWD and County prepared a boundary modification request that was submitted to DWR in January 2016.
The three agencies, SVWD, SLVWD, and County, are committed to working with each other and engage other stakeholders in forming a GSA and developing a GSP after the State approves the boundary modification request.
What is Groundwater?
Groundwater, known as water held underground beneath the Earth’s surface in the soil or in pores and crevices in the rock, is a beneficial resource nationally and within California as it is used for drinking water by more than 50 percent of the people in the United States, including almost everyone who lives in rural areas. For California, about 38 percent of groundwater make up the state’s total water supply, with the largest use for groundwater is for crop irrigation.
Managing groundwater resources is critical. That’s why the state of California passed the Sustainable Groundwater Management Act, which requires the adoption of groundwater management plans to sustain groundwater resources, and assist with maintaining reliable and resilient water supplies throughout California.
Prior Basin Management Activities
The major water purveyors that rely on the supply from the Santa Margarita Groundwater Basin are SVWD, SLVWD, and MHA. 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 (GWMP) in accordance with AB3030, also known as the Groundwater Management Act under Water Code section 10750. The overall purpose of the GWMP is to be a planning tool that helps to guide SVWD in the management of the quantity and quality of the groundwater supply and to comply with the requirements of AB3030. The main goal of the GWMP is to better manage the aquifers providing the community’s drinking water. The Basin Management Objectives as stated in the GWMP are:
Encouragement of public participation through an annual report of groundwater management activities and its presentation at one or more public meetings;
Coordination with other agencies;
Continued monitoring and evaluation of groundwater conditions;
Implementation of groundwater augmentation projects; and
Investigation of groundwater quality and prevention of groundwater contamination.
In 1995, SVWD, SLVWD, MHA, Lompico County Water District (LCWD), City of Scotts Valley and County of Santa Cruz signed a Memorandum of Understanding forming Santa Margarita Groundwater Basin Advisory Committee that has been actively involved in the cooperative groundwater management of the basin since then.
Much of the technical information and interpretations used to inform the basin management have been based on modeling and technical studies in the SMGB. The earliest modeling in the SMGB was done by Johnson (1988) who constructed a groundwater model of a portion of the Quail Hollow area to help evaluate the cause of elevated nitrate concentrations in groundwater produced from SLVWD wells. The Johnson model and an earlier model of Scotts Valley (Jacobvitz, 1987) were incorporated into a regional groundwater flow model by the Association of Monterey Bay Area Governments (AMBAG) in 1992 as part of the draft Santa Margarita Groundwater Basin Management Plan (Watkins-Johnson Environmental, 1993) that was not adopted. Portions of the AMBAG model were later updated by SVWD (Todd Engineers, 1997). These models were all run under steady-state conditions that did not evaluate time-varying conditions.
Johnson (2001 and 2002) later updated the Quail Hollow model through a detailed data assessment and conceptual model interpretation that led to the development of a transient model of the Santa Margarita and Monterey for the Quail Hollow area. Johnson (2003) provided a detailed data assessment and conceptual model interpretation of the Pasatiempo area west of Scotts Valley, but the numerical model was not constructed.
The Santa Margarita Groundwater Modeling Project of 2015 updated the SMGB model developed in 2006 (EITC, 2006) for SVWD with funding from the DWR Local Groundwater Assistance Grant Program. The numerical model was based on a conceptual model of the basin developed with input and oversight from a technical advisory committee representing interested local agencies. The model was also used as part of the Phase 1 Conjunctive Use Project (Kennedy/Jenks, 2011) by Santa Cruz County to evaluate potential groundwater recharge projects in SMGB. SVWD has regularly updated the SMGB model as part of their Groundwater Management Program to evaluate changes in groundwater storage. The most recent update of that previous version of the SMGB model included data through 2012.
Key Basin Management Goals
Goal 1: Ensure water supply reliability for current and future beneficial uses
Goal 2: Maintain water quality to meet current and future beneficial uses
Goal 3: Prevent adverse environmental impacts
These goals will be re-evaluated as the SMGWA embarks on developing its Groundwater Sustainability Plan.
The SMGWA has been working and focusing on:
Formation of a Groundwater Sustainability Agency (GSA) – Complete
Request Basin Boundary Revision to DWR – Complete
Develop a Groundwater Model – In progress
Developing a Work Plan to prepare a Groundwater Sustainability Plan – In progress
Public Outreach and Education – Ongoing
Develop the Groundwater Sustainability Plan – In progress