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Close-up of a natural stone water feature.

For many decades, the City of Corona (Corona), City of Norco (Norco), and Home Gardens County Water District (HGCWD) have been steadfast stewards of groundwater resources in the Temescal Groundwater Subbasin, actively managing groundwater to protect water quality and maintain a reliable and sustainable water supply. For Corona, Norco, HGCWD, and other water agencies, it’s getting more and more difficult to ensure long-term groundwater sustainability, with climate variability, growth in urban water use, availability and cost of imported water, and other factors.

To assist water agencies like Corona, Norco, and HGCWD in meeting these significant groundwater challenges, the state-wide Sustainable Groundwater Management Act was passed in 2014. This law outlines new requirements and tools for ensuring the long-term sustainability of these critical sources of water supply.

Updates

Temescal Basin Groundwater Sustainability Plan Agendas and presentations from previous meetings and workshops can be found at the bottom of this webpage.

About Groundwater & Our Basin

What is Groundwater?

Groundwater matters to everyone. It’s an important source of water stored in the earth beneath our feet, in spaces between sand, soils, and fractured rock known as an aquifer. Layers of aquifers make up a groundwater basin, which can extend for miles. Groundwater is a critical buffer against the impacts of drought and climate variability/change, and plays a vital role in maintaining our region’s (and the State’s) economic and environmental sustainability. Sustainable groundwater management balances groundwater resources in a manner that ensures basin resiliency, which greatly benefits present and future generations. To learn more about groundwater, visit the California State Water Resources Control Board web page.

Temescal Groundwater Basin

The Temescal Basin shown below is within Riverside County and is largely covered by the City of Corona, the City of Norco, and the Home Gardens County Water District, with some areas within federal and unincorporated county lands. The City of Corona is leading the Temescal Groundwater Sustainability Agency (GSA) in preparing the Groundwater Sustainability Plan for the basin in cooperation with the other agencies of the GSA.

Basin Conditions

The City of Corona, City of Norco, and HGCWD have participated in active management of water resources in the Temescal Subbasin. This management has included cooperation in preparing the 2008 Groundwater Management Plan and participation in regional Santa Ana Watershed planning and management. Historical management provides a good foundation for SGMA. However, SGMA entails a rigorous, systematic process with significant requirements.

Sustainable management of the Temescal Basin is critical to local water supply reliability. The three local agencies (both individually and jointly) have developed water supply portfolios including imported water, groundwater from multiple local basins, and reclaimed water for landscape irrigation. Water conservation measures also have been implemented, providing an important tool for responding to water shortages. Local agencies are active in regional water management, and recognize that local groundwater is a primary source of supply and needs to be reliable. The Temescal Basin area historically has experienced significant land use changes —shifting from agricultural to urban land uses—and water demand increases. This transition was achieved in part with reliance on local groundwater. In fact, the Corona Groundwater Management Plan (GWMP) indicated that overdraft conditions occurred in the Temescal Basin during the last three years of the 1990 to 2004 period as pumping increased. While conditions subsequently improved, this illustrates that overdraft can occur. Concerns about water supply reliability persist, given the uncertainties of imported water and climate change. Moreover, groundwater quality generally is poor; in fact, sustainable groundwater use is dependent on treatment at the Temescal Desalter. SGMA and the GSP process provide an important set of tools for the City and GSA partners to address these conditions and plan for water supply reliability into the future.

About the SGMA

The Sustainable Groundwater Management Act

The Sustainable Groundwater Management Act (SGMA) is State law requiring that groundwater basins are made sustainable. This essentially means maintaining balanced levels of pumping and recharge, and assuring reliable water quality. Everyone who uses groundwater should recognize the vast importance of basin sustainability for today, and for our children, their children, and the generations beyond. SGMA provides a comprehensive framework for basin sustainability, additional technical analysis and quantification of many aspects of basin sustainability and management, extensive and more detailed descriptions of basin setting and conditions, and more comprehensive monitoring of groundwater use, groundwater quality, and groundwater levels, including metering of groundwater usage.

SGMA enables eligible local agencies to form Groundwater Sustainability Agencies (GSAs), develop Groundwater Sustainability Plans (GSPs) for designated basins in their jurisdiction, and achieve groundwater sustainability within 20 years of GSP implementation. It provides for assistance by State agencies such as the Department of Water Resources (DWR), and also mandates State intervention if local agencies fail to meet SGMA’s requirements. SGMA is required by State law, but it’s also simply a good idea for water and land use planning agencies and their communities, as it:

Offers tools for managing and sustaining our groundwater supplies

Supports urban water use and helps meet the challenges of urban growth
Supports community access to groundwater
Supports groundwater-dependent habitats and offers environmental benefits
Helps prepare local agencies to address climate change/weather variability challenges
Provides an opportunity for agencies to actively manage groundwater resources to best accommodate changing circumstances, conditions, populations, and land uses

SGMA Groundwater Management Tools

SGMA’s rigorous, required processes will build on the solid foundation of management practices that Corona, Norco, and HGCWD have developed, with additional information and analyses, review of basin conditions considering new sustainability criteria, update of basin modeling, and renewal of the planning process. SGMA also defines the scope of groundwater management to the entire basin area, potentially requiring expansion of data collection, monitoring, and management to a wider area.

SGMA enables a GSA the option to adopt regulations requiring the installation of water-measuring devices on all groundwater wells producing/pumping more than two acre-feet a year within the basin boundaries at the expense of the operator or owner.

Under SGMA, a GSA may also adopt other tools including:

Conduct investigations of water rights

Acquire property and water rights
Adopt rules, regulations, and ordinances
Require the registration of wells
Utilize recycled water as a supply source

SGMA Roles & Responsibilities

Groundwater Sustainability Agency

The City of Corona (Corona), City of Norco (Norco), and Home Gardens County Water District (HGCWD) have entered a Memorandum of Understanding (MOU) to establish the Temescal Basin Groundwater Sustainability Agency (Temescal GSA) for the Temescal Groundwater Basin. Through the MOU, Corona has accepted the primary responsibility to develop a Groundwater Sustainability Plan (GSP) for the Temescal Basin, to submit it to DWR, and to prepare Annual Reports thereafter. The GSP will be developed jointly among the three agencies, with coordinated implementation toward sustainable management.

The Temescal Basin has been designated by the DWR as medium priority, recognizing that it is an important source of water supply, has been well-managed, and is not critically over-drafted. For medium-priority basins such as the Temescal Basin, GSPs must be completed by 2022 and demonstrate sustainability by 2042. SGMA lays out a required schedule with deadlines for GSP preparation, annual reporting, and GSP updates every five years. The GSP must include an implementation plan (with activities, estimated costs, and scheduling) that will support groundwater sustainability into the future. To help with costs of GSP preparation, Corona applied for and received a grant from the Department of Water Resources under the Proposition 1 Sustainable Groundwater Planning Grant Program. By law, the Temescal GSA may collect fees to help pay for the costs of implementing the GSP and maintaining it into the future.

The Temescal GSA must produce a GSP describing how basin sustainability will be achieved. The GSP must document:

The GSA and its decision-making process
Stakeholder outreach and communication
The GSP Plan Area and its local agencies, land uses, planning, water supply and demand, and existing groundwater monitoring and management
The physical setting of the groundwater basins including geology, current and historical groundwater conditions, water budgets, and interactions between the groundwater and surface water systems
How sustainability criteria are defined to guide local management

Local management actions and projects and how they will be implemented
What monitoring is needed to identify problems and to demonstrate sustainability

Recognizing that groundwater management in California is best accomplished locally, SGMA supports local control of the GSA/GSP process, and the involvement of local agencies, water providers, groundwater users, and environmental, business, and agricultural interests. GSP preparation involves collaboration among local water management and land use planning agencies, and substantial outreach to stakeholders and the community including a series of workshops, distribution of informational materials, and opportunities to review and comment on draft sections of the GSP. The goal is to inform, educate, and engage all interested parties in order to create an effective, useful, and successful GSP.

The Temescal GSA is governed by the city councils and board of directors of the three member agencies. The meetings of the Temescal GSA board will take place during regular meetings of the Corona and Norco city councils and the HGCWD Board of Directors.

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Temescal Groundwater Community Involvement

SGMA requires a communications plan to reach and involve the community and stakeholders around the Groundwater Sustainability Plan. The Temescal Groundwater Sustainability Agency (GSA) recognizes that this is a critical aspect of ensuring that this process is transparent, engaging, effective, and fully available to the members of the community. Overall community engagement, which includes involvement of diverse social, cultural, and economic elements of the population within the basin area, helps the Temescal GSA to best consider the full range of interests of all beneficial uses and users of groundwater, as the Plan moves forward.

The general goals of the Temescal GSA community engagement efforts are to:

Inform stakeholders of the GSP development process, including purpose, opportunities and issues, core recommendations, and timeline.
Provide meaningful opportunities for stakeholders and the public to learn, ask questions, and provide input.
Involve the many diverse communities and stakeholders of Corona, Norco, and Home Gardens, recognizing that different approaches may be needed to reach specific populations like Disadvantaged Communities, and flexibility and adaptation in approach may be required.
Ensure a transparent process where stakeholders and the public can understand what important discussions are taking place, how they can participate in them, and how input is being used.

To do this, the Temescal GSA is producing and distributing informational fact sheets, providing specific website resources on SGMA/GSP, utilizing social and traditional media, and conducting a number of public workshops around key issues and milestones in the GSP preparation.

Interested community members are encouraged to sign up to receive email updates including notices of upcoming community workshops. The workshop schedule will also be posted on this website.

Although not required by SGMA, the Temescal GSA values the contributions of a Technical Advisory Committee (TAC), to assist in reviewing and contributing to the technical aspects of the GSP as its elements are produced. The TAC is made up of individuals selected to represent GSP-related subject areas, including but not limited to community, technical, and land use planning fields. This diverse group of experts in their respective fields will be responsible for reviewing the GSP scope of work, draft products, and materials prepared by consultants, analyzing them, and providing recommendations to the GSP Technical Team to develop a technically-sound GSP.

Temescal GSA

Technical Advisory Committee
Temescal Basin Groundwater Sustainability Plan

TECHNICAL ADVISORY COMMITTEE 3M Industrial Mineral Products Division All American Asphalt California Regional Water Quality Control Board - Santa Ana Region (8) - City of Norco Home Gardens County Water District Riverside County Flood Control and Water Conservation District Corona City Council Member – Jacque Casillas Corona City Council Member – Wes Speake City of Corona Utilities Department