REQUEST FOR CITY COUNCIL AND
CORONA UTILITY AUTHORITY ACTION
DATE: 01/05/2022
TO: Honorable Mayor and City Council Members
Honorable President and Board Members
FROM: Utilities Department
SUBJECT:
Title
Public Hearing and Resolution adopting the Temescal Basin Groundwater Sustainability Plan.
End
EXECUTIVE SUMMARY:
The City prepared a Groundwater Sustainability Plan for the Upper Santa Ana Valley Groundwater Basin, referred to as the Temescal Basin. The Groundwater Sustainability Plan (GSP) has been prepared in compliance with the Sustainable Groundwater Management Act (SGMA) and with guidance from the California Department of Water Resources (DWR). SGMA requires all medium- and high-priority groundwater basins to be managed by a Groundwater Sustainability Agency (GSA) and prepare a GSP. The City prepared the Temescal Basin GSP in concert with other agencies in the Temescal Basin and in consideration of input from local stakeholders. Through this Resolution, the City will formally adopt the Temescal Basin GSP as the lead agency of the Temescal Basin GSA.
RECOMMENDED ACTION:
Recommended action
That the:
a. City Council hold a public hearing regarding the Temescal Basin Groundwater Sustainability Plan.
b. City Council adopt Resolution No. 2022-001, adopting the Temescal Basin Groundwater Sustainability Plan.
c. Corona Utility Authority, review, ratify, and to the extent necessary, direct the City Council to take the above actions.
Body
BACKGROUND & HISTORY:
On September 16, 2014, the Governor signed a three-bill package, known collectively as the Sustainable Groundwater Management Act (SGMA), into law that established a new structure for sustainable groundwater management. The Sustainable Groundwater Management Act went into effect on January 1, 2015. SGMA requires all medium- and high-priority groundwater basins, as designated by the California Department of Water Resources (DWR) Bulletin 118, to be managed by a Groundwater Sustainability Agency (GSA) or multiple GSAs. The Temescal Basin GSA was created consisting of the City of Corona, City of Norco, and the Home Gardens County Water District. Through a Memorandum of Understanding (MOU), the City of Corona accepted the responsibility to develop a Groundwater Sustainability Plan (GSP) for the Temescal Basin, a medium-priority groundwater basin.
ANALYSIS:
The City of Corona Purchasing division issued a Request for Proposals (RFP) for GSP development in November 2019. The RFP was awarded to Todd Groundwater and approved by the City Council on May 20, 2020. The approved proposal included two subconsultants, Carollo Engineers and Kearns & West. Todd Groundwater was the lead consultant assisting the City of Corona in preparing a GSP for the Temescal Basin. The City of Corona has been working with Todd Groundwater since May 2020 to prepare a GSP for the Temescal Basin. The GSP has been prepared to be consistent with SGMA, using guidance from DWR, and input from local stakeholders.
Public Outreach and Stakeholder Engagement
The Temescal Basin GSP preparation was a transparent process where stakeholders and the public were invited to participate and comment throughout its creation. A dedicated Temescal Basin groundwater webpage was created, hosted by the City of Corona. The webpage was updated with meeting dates/times, registration links, meeting presentations, meeting summaries, and drafts of the GSP chapters as they became available. A Technical Advisory Committee (TAC) was formed from select neighboring agencies and local stakeholders. The TAC members included:
• City of Corona - Utilities Department
• City of Corona - Council Members
• Home Gardens County Water District
• City of Norco
• Riverside County Flood Control and Water Conservation District
• California Regional Water Quality Control Board - Santa Ana Region 8
• All American Asphalt
• 3M Industrial Mineral Products Division
Four TAC meetings were held on April 19, 2020, November 18, 2020, February 17, 2021, and June 16, 2021. TAC members received presentations on SGMA, groundwater conditions in the Temescal Basin, draft plans for continued sustainable management of the Basin, and drafts of GSP chapters as they were created to review and provide feedback to the Temescal Basin GSA and the consultant team.
The Temescal Basin GSA also hosted public workshops where anyone interested in the Temescal Basin GSP could attend, comment, and/or ask questions. Three Public Workshops were held on September 29, 2020, March 2, 2021, and July 8, 2021. The public workshops were open to the public. In order to promote participation, the Temescal Basin GSA maintained an open-enrollment “Interested Parties List” that was used to distribute information regarding meeting dates, times, and availability of GSP component drafts. All meetings were held virtually via Zoom, and were simultaneously broadcasted on YouTube, Facebook, and Corona’s public broadcast cable channel. The Public Workshops were all led in English while simultaneously translated to Spanish. Viewers who wished to view meetings in Spanish could do so via a “Spanish room” option within the Zoom platform.
Additional outreach included distribution of public information fliers in both English and Spanish and targeted outreach meetings to local community leaders and community advocacy groups.
Basin Setting
The Temescal Basin is bound on the west by the Santa Ana Mountains and the east by low-lying El Sobrante de San Jacinto and La Sierra Hills and it is adjacent to the Bedford Coldwater, Chino, and Riverside-Arlington Sub-basins of the Upper Santa Ana Groundwater Basin and the Coastal Plain of the Orange County Basin.
The Temescal Basin is located within one of the structural blocks of the Peninsular Ranges of Southern California. The Basin occurs in a linear low-lying block, referred to as the Elsinore-Temecula trough, that extends from Corona to the southeast some 30 miles and was formed along an extensive northwest-southeast trending fault zone including the Elsinore, Chino, and related faults.
The basin-fill alluvial deposits and, to some extent, the underlying sedimentary units make up the aquifers in the Basin. Three aquifer packages provide water supply to wells in the Basin: the Channel Aquifer, the Alluvial Fan aquifers, and, to a lesser extent, consolidated sandstone aquifers. Of these three aquifers, the Channel Aquifer is the only principal aquifer as it is the most productive aquifer and provides most of the groundwater supply in the Basin.
Groundwater Conditions
Water levels in the Channel Aquifer vary in response to wet and dry hydrologic cycles. Increased pumping and prolonged drought have resulted in a slight decline in water levels over the past twenty years. Groundwater levels reached their respective highs in the early 1980s in response to a wet hydrologic cycle that began in 1978. The lowest groundwater levels generally correspond to dry periods and periods of increased pumping, though the responses throughout the Basin are not uniform.
Total Dissolved Solids (TDS) and nitrates are the primary water quality constituents of concern in the Basin. Groundwater in the Basin is somewhat mineralized, with high TDS concentrations in many monitored wells. Groundwater in the Basin has been impacted by human activities both in the Basin and watershed including agricultural, urban, and industrial land uses. Elevated nitrate concentrations have been documented in the Basin since, at least, the 1950s.
Water Budget
A water balance (or water budget) is a quantitative tabulation of all inflows, outflows, and storage change of a hydrologic system. This GSP contains a detailed water balance for both the groundwater system and surface water system of the Basin. The water budgets were developed for time periods representing historical, current, future no project (baseline), and future growth plus climate change conditions. The two future scenarios were simulated to test sustainability, and both showed sustainable conditions in the future.
Sustainable Management Criteria
The sustainable management goal of the Temescal Basin is to sustain groundwater resources for the current and future beneficial uses of the Basin in a manner that is adaptive and responsive to the following objectives:
• Provide a long-term, reliable, and efficient groundwater supply for municipal, industrial, and other uses;
• Provide reliable storage for water supply resilience during droughts and shortages;
• Protect groundwater quality;
• Support beneficial uses of interconnected surface waters; and
• Support integrated and cooperative water resource management.
This goal is consistent with SGMA and is based on information from other aspects of the GSP.
A GSP must develop quantitative sustainability criteria for all applicable sustainability indicators that allow the Temescal Basin GSA to define, measure, and track the progress of sustainable management criteria of the Temescal Basin. These criteria include the following:
• Undesirable Result - significant and unreasonable conditions for any of the six sustainability indicators which are groundwater level declines, groundwater storage reductions, land subsidence, degradation groundwater quality, seawater intrusion, and depletion of interconnected surface water (including impacts on groundwater dependent ecosystems).
• Minimum Threshold (MT) - numeric value used to define undesirable results for each sustainability indicator.
• Measurable Objective (MO) - specific, quantifiable goal to track the performance of sustainable management.
The sustainability indicators and sustainable management criteria are clearly defined and provide a quantitative analysis of the Basin’s sustainability. As the Basin has been managed without significant undesirable results, the sustainability criteria are defined to avoid future undesirable results.
Monitoring Network
The monitoring network for GSP implementation has been established to document groundwater and related surface conditions as relevant to the sustainability indicators, MTs, and MOs. The components of the monitoring network are built from existing programs and will be carried out by the Temescal GSA. The monitoring network comprises a set of existing wells in which groundwater elevations and water quality parameters have been measured historically and will continue to be measured in the future. There are currently 27 existing wells in which groundwater elevation has and will be monitored. Many of these wells are also used for monitoring groundwater quality, along with other water supply and water quality monitoring wells in the Temescal Basin. Additional monitoring wells may be added to the network in the future as necessary. The GSP includes plans to add several shallow wells for monitoring interconnected surface water conditions in the southern part of the Prado management zone.
Projects and Management Actions
During the preparation of the GSP, the Temescal Basin GSA identified five specific management actions (Actions) and three projects (Projects) to achieve the sustainability goal. The Actions are generally focused on data collection, storage and reporting of information necessary to monitor sustainability, and assessment of when Actions may be necessary (i.e., when MTs are approached or exceeded). The projects are generally designed to reduce uncertainty in areas where data gaps have been identified during development of the GSP. These projects and management actions are aimed at achieving sustainability goals and responding to changing conditions in the Basin.
GSP Implementation
The official adoption of the GSP by the Temescal Basin GSA will initiate Plan implementation. After submittal of the GSP to DWR, and during the DWR review period, the Temescal Basin GSA will continue to communicate with stakeholders via the City of Corona’s website and begin implementing the projects and management actions described in the GSP. The Plan will be implemented to sustainably manage groundwater in the Basin under the authority of the Temescal Basin GSA and its member agencies.
The Temescal Basin GSA is required to submit an annual report to DWR by April 1st of each year following adoption of the GSP. The first annual report will be due in April of 2022. The Temescal Basin GSA has committed to implementing the GSP upon adoption and completing the projects and management actions necessary to monitor and maintain sustainability within the first five years of initiation of the GSP.
The Temescal Basin GSP is presented in draft form to allow for modifications based on public comments during the public hearing portion of the Council meeting. After adopting Resolution 2022-001, the Temescal Basin GSP will be finalized and submitted to DWR as a final document.
FINANCIAL IMPACT:
Funding for the recommended action is included in the Fiscal Year 2022 Utilities Department Operating Budget. Funding in future fiscal years will be recommended through the budget process.
ENVIRONMENTAL ANALYSIS:
This action is exempt pursuant to Section 15061(b)(3) of the Guidelines for the California Environmental Quality Act (CEQA), which states that a project is exempt from CEQA if the activity is covered by the commonsense exemption that CEQA applies only to projects that have the potential for causing a significant effect on the environment. Where it can be seen with certainty that there is no possibility that the activity in question may have a significant effect on the environment, the activity is not subject to CEQA. This action involves the approval of a plan, and there is no possibility that adopting this resolution will have a significant effect on the environment. Therefore, no environmental analysis is required.
PREPARED BY: KRISTIAN ALFELOR, OPERATIONS MANAGER
REVIEWED BY: TOM MOODY, DIRECTOR OF UTILITIES
Attachments:
Exhibit 1 - Resolution No. 2022-001