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Lemoore, CA – The South Fork Kings Groundwater Sustainability Agency (SFKGSA) Board unanimously adopted the Tulare Lake Subbasin Groundwater Sustainability Plan at their January 16 meeting. The SFKGSA will use the Groundwater Sustainability Plan (GSP) as a roadmap to balance its groundwater. For the initial implementation period, the SFKGSA Board is operating under the assumption of an estimated groundwater overdraft of 38,000 acre feet per year. The GSP includes a full suite of supply enhancement and demand reduction programs the SFKGSA Board may consider to reduce this estimated overdraft number.

SFKGSA is the one of five groundwater sustainability agencies within the Tulare Lake Subbasin that have worked together to complete the Tulare Subbasin Groundwater Sustainability Plan. In addition to the SFKGSA, the Mid-Kings River GSA, El Rico GSA, and Tri-County Water Authority GSA have all unanimously adopted the GSP. The Southwest Kings GSA will consider adoption at a special board meeting on January 27. Upon completion of the adoption process, the GSP will be submitted to the State by the deadline of January 31. 

Once the Tulare Lake Subbasin GSP is posted to the Department of Water Resources (DWR) web portal, it will be open to public comment for a minimum of 60 days. Public comments will be compiled and considered in DWR’s assessment of the GSP. DWR has two years from date of submission to evaluate and assess the Plan.

The SFKGSA will begin implementing their GSP immediately after submittal. The SFKGSA Board will begin developing policies and prioritizing the management actions and projects within the GSP to be implemented. In addition, the first annual report must be completed and submitted to DWR by April 2020.

South Fork Kings GSA’s technical consultant, Geosyntec presented at the May 23 Board workshop the proposed well network to be included in the Groundwater Sustainability Plan. Three locations within the SFKGSA service area have been identified. The wells at these locations are where the GSA will measure water levels to report to the State Department of Water Resources.

The wells will provide data from three separate levels in the aquifer from shallow to deep: zones A, B, and C. A-zone wells are located in the shallow perched area of the aquifer within the top 100 feet above the A Clay. The B-zone wells are below the A Clay layer and above the Corcoran Clay, the deepest clay layer. It is an unsaturated aquifer so water levels go up and down. The C-zone are wells installed below the Corcoran Clay. It is a confined aquifer so there is less variation of what is occurring in the aquifer at that level.

The network will use existing wells but will also require the drilling of additional wells to ensure adequate data is collected. Currently, there are seven existing wells in the three locations that are part of the Kings River Conservation District’s monitoring network. There is one well in the A-zone and six wells in the B-zone. Five additional wells will need to be installed to complete the network, two in the A-zone and three wells in the C-zone.

The South Fork Kings is tasked with stabilizing groundwater levels to reach sustainability under SGMA. This means reducing the near 45,000 acre-feet per year of groundwater overdraft in the GSA, an estimation calculated by the subbasin’s groundwater model. A menu of projects and management actions to reduce the groundwater overdraft was presented by the GSA’s technical consultant at the April 18th Board workshop.

A combination of supply-side and demand-side solutions will achieve sustainability. Solutions will either increase available water supply to offset groundwater pumping and/or will decrease the demand for groundwater. The technical consultants outlined specific projects and actions for consideration during these next few years of sustainability planning.

The percentages represent the proportion of overdraft each item will solve. Please note these proportions and management actions are in preliminary draft form.

On the demand side, on farm improvements in irrigation efficiency and water treatment could save an estimated 2,230 acre-feet per year. Land retirement with opt-in incentives and land repurposing, such as solar farms, could yield a savings of 1,340 acre-feet per year.

There is potential to cooperate on supply-side projects that benefit the entire subbasin. One example is cost-sharing for constructing recharge basins on especially suitable soils in surrounding GSAs. Although primarily used by municipalities, Aquifer Storage and Recovery (ASR), a process in which water is injected into the aquifer for storage and subsequent withdrawal, is being studied for agricultural application. ASR has the potential to reduce overdraft by an estimated 10,258 acre-feet per year.

As the South Fork Kings GSA progresses with its Groundwater Sustainability Plan (GSP), balancing SGMA compliance with economic impacts to the service area is a high priority for the Board. Developing creative solutions and adaptive management actions will ultimately drive sustainability success and secure the region’s water supply for years to come.

At the October 18th Board workshop, the South Fork Kings GSA’s technical consultant Geosyntec introduced potential management concepts for mitigating groundwater overdraft in the South Fork Kings area. SGMA requires subbasins become sustainable by the year 2040; the means to achieve that mandate are the projects and management actions that will be included in the Tulare Lake Subbasin Groundwater Sustainability Plan (GSP).

A reduction in groundwater use, an increase in groundwater recharge, and the implementation of programs and management actions to increase water use efficiency are broad strategies for establishing a trajectory toward sustainability.

Project concepts to reduce groundwater use include the acquisition of additional surface water, or crop conversion to less water demanding crops. Both solutions carry the potential to offset groundwater demand. Increasing the amount of groundwater recharged in the South Fork Kings area to stabilize water levels can be accomplished a number of ways, either through the construction of additional dedicated recharge basins or through “incidental” means by way of flood irrigation and canal seepage.

To provide flexibility, the GSA seeks to provide a menu of programs and management actions for landowners in its service area. Program concepts may include water markets and groundwater crediting systems, allowing water trading among growers within the GSA and consequently incentivizing water use efficiency.

The management concepts discussed are in the early stages of consideration. The South Fork Kings GSA is working to factor local conditions, economic constraints, and stakeholder input as it identifies a project portfolio that achieves State-mandated sustainability.

The South Fork Kings GSA is coordinating with the other five GSAs of the Tulare Lake Subbasin to complete a Groundwater Sustainability Plan (GSP) by the state-mandated deadline of January 31, 2020. Although the subbasin will submit a single GSP that outlines the path toward sustainability, the South Fork Kings GSA’s contribution will ensure local issues, projects and management actions are included.

The GSP schedule is pictured below (click to enlarge). Drafted chapters, Plan Area and Basin Setting, provide a foundational framework to establish the Sustainable Management Criteria. This chapter is anticipated for completion in November 2018.

GSP Schedule

Sustainable Management Criteria are the goals that measure success of groundwater level stabilization. The criteria includes:

          Measurable objective: average maintained groundwater level over the long-term that must be met by 2040.

          Minimum threshold: the lowest possible groundwater level allowed in the worst case scenario. Level cannot cause an undesirable result (ie. significant and unreasonable degraded water quality) and thus cannot be arbitrary.

These metrics are included in the GSP and must be approved by the CA Department of Water Resources.

At the July 19^th Board Workshop, South Fork Kings Groundwater Sustainability Agency (GSA) technical consultants Geosyntec provided a Groundwater Sustainability Plan (GSP) update as well as an overview of the components and capabilities of the groundwater model, a critical GSP component for setting sustainability objectives and identifying potential projects for the GSA. The groundwater model is in preliminary draft form, and the information presented has not been accepted or approved by any organizations.

The Groundwater Sustainability Plan is a detailed roadmap for how the Tulare Lake Subbasin will reach long-term sustainability. The law requires the GSA to submit a GSP to the State by January 2020; the South Fork Kings GSA has agreed to coordinate with the five other GSA’s within the Tulare Lake Subbasin to submit a single GSP. The South Fork Kings GSA’s role within the larger Subbasin effort is to provide specific input for each component of the GSP that includes GSA-specific concerns, projects, and management actions (click here to view the CA Department of Water Resources GSP Outline).

A fundamental component of the GSP is the Basin Setting chapter. The chapter includes foundational information regarding the groundwater conditions of the Tulare Lake Subbasin, including the groundwater model, and works to provide context and direction for setting measurable sustainability objectives and identifying solutions to reach those objectives. With data input, the groundwater model uses accurate representation of past conditions to create confidence in future predictions. It utilizes data from the river/canal system, crop demand, subsidence, and well monitoring to assess groundwater conditions such as inter-basin groundwater flows and groundwater pumping amounts.

The model can use data to simulate groundwater contour maps like the one pictured below (click to enlarge) of the Tulare Lake Subbasin. Groundwater contour maps show groundwater elevation (feet above mean sea level) along contour lines to illustrate the direction that groundwater flows within the Subbasin. Water flows perpendicular to contour lines from higher elevations to lower elevations.

The map above was created using the preliminary groundwater model, and is in preliminary draft form and subject to change pending data improvements and model recalibration.

The map was created using data from the period 1990-2016 and indicates groundwater elevation and flows in the Tulare Lake Subbasin above the Corcoran Clay. The blue arrows indicate the general directions that groundwater is flowing within the Subbasin. Groundwater flows generally from east to west in the northern part of the Subbasin, but the elevations indicate the Tulare Lake bottom in the southern half of the GSA is a mound that causes water to flow all directions out of the lake bed.  This type of information is an important factor for calculating a groundwater overdraft amount, since groundwater may be flowing into other GSA’s but out of others, or a combination of both.

Groundwater flows and storage change are a key coordination issue in GSP development; the values calculated by the South Fork Kings GSA groundwater model need to be consistent with technical work in adjacent GSA’s to ensure appropriate groundwater overdraft amount is assigned and accounted for across the Subbasin.

The model is currently in its first iteration, and the technical consultants plan to recalibrate it over the coming months to include improved data and information for sharper accuracy in modeling predictions. The model is just one part of a larger picture required for the GSP, but it is an important aspect of plan development for the South Fork Kings GSA as it helps shape the programs and projects that will be implemented to reach sustainability by 2040.