The Model, the Data and Groundwater Sustainability

At the February 1 Board meeting, South Fork Kings Groundwater Sustainability Agency (GSA) technical consultant, Bob Anderson of Geosyntec Consultants, covered what a model can and cannot do and the importance of data and how they will be used in determining groundwater sustainability in the Tulare Lake Subbasin.

To guide regional activities necessary to implementing the Sustainable Groundwater Management Act of 2014 (SGMA), a Groundwater Sustainability Plan (GSP) will be prepared to cover the entire Tulare Lake Subbasin (see diagram below). The South Fork Kings GSA is one of six GSAs within the subbasin that must coordinate their planning to complete a shared GSP, but coordination is not limited to the six GSAs.

The Tulare Lake Subbasin is delineated by a political rather than scientific boundary. The geological or physical boundary of the principal aquifer, the San Joaquin Valley Basin, is bound on the east by the Sierra Nevada, to the west by the Coastal Range and north and south by Sacramento and the Tehachapi Mountains. The Tulare Lake Subbasin is 1 of 16 subbasins within very large (9-million acre/14,000 sq/mi) San Joaquin Valley Basin.

In order to understand and address water flow between political boundaries SGMA also requires that GSAs in each subbasin coordinate with GSAs in neighboring subbasins. The visual below shows the South Fork Kings GSA, the five other GSAs in the Tulare Lake Subbasin and their neighboring subbasins.

The core element for the GSP is its water budget, which describes the amount of water coming into a subbasin versus the amount going out. A good comparison for understanding how a water budget works is to think of it as a bank account. SGMA requires that a subbasin identify impacts of over-pumping and then take corrective actions that will result in long-term sustainability. It is up to the South Fork Kings GSA Board to define what “sustainable” means within its jurisdiction and in the entire Tulare Lake Subbasin through coordination with neighboring GSAs.

Water Budget Diagram

A computer model is a tool that breaks down an area into thousands of individual water balance cubes that when combined can make very complex groundwater flow and water balance calculations.

The computer model for the Tulare Lake Subbasin will assess the six undesirable results as defined by SGMA. Defining these six undesirable results for the South Fork Kings will be the roadmap to sustainability for the groundwater subbasin. The diagram below illustrates how a model computes one undesirable result, the chronic lowering of groundwater levels.

Models need data. Data is the best indication of what is going on. Where data does not exist, assumptions must be made and therefore the more data there is the better the analysis will be. Some data is already available through sources like the Department of Water Resources (DWR) that has collected depth to groundwater data for years.

Other important data needed include surface water diversions and cropping patterns. In the absence of measured groundwater well pumping rates, the Tulare Lake Subbasin model will back its way into a groundwater pumping estimate using cropping pattern data coupled with irrigation estimates and measured surface water diversions.

Tulare Lake Subbasin Pumping = Crop Consumptive UseSurface Water Delivery

The model and data are a couple of the pieces needed to complete the GSP by the State’s deadline of January 2020. 

Board Approves Data Sharing Agreements with North Fork Kings GSA, Westlands Water District

The Board approved entering into two agreements, one with the Westlands Water District and the second with the North Fork Kings Groundwater Sustainability Agency to share relevant data and to establish a set of common assumptions on groundwater conditions within five (5) miles of the boundary between the South Fork Kings GSA and these two neighboring agencies. The agreements support the effort to coordinate planning efforts with neighboring GSAs and subbasins.

Board Approves Preparation of Engineering Report for 218 Election

At a regular meeting held on September 21st, the South Fork Kings GSA Board approved a task order with Geosyntec Consultants, Inc. to prepare an engineering report  and to conduct a Prop 218 assessment election. The engineering report will include an analysis for the costs to prepare a Groundwater Sustainability Plan, costs for ongoing administration, and the recovery of startup costs incurred by the South Fork Kings member agencies. Components of the report include background information on the GSA, summary of GSA operations, a description of the proposed assessment, a determination of benefits derived from the assessment, and procedures to implement the assessment. The proposed timeline to complete the engineering report and conduct a 218 election is April 2018. The estimated cost to complete the entire process is $29,560.

In other business, the Board approved a task order in the amount of $18,000 with Geosyntec Consultants to conduct initial data assessment and modeling review along with reviewing the proposed scope of work to be included in a planning grant application for Proposition 1 funding. 

Contract Approved with Geosyntec Consultants

The South Fork Kings GSA Board Members approved a contract with Geosyntec Consultants for technical engineering consulting services at a special board meeting held on August 17. The contract has two tasks. Task 1 is to provide general project management tasks through the end of Fiscal Year 2018. This task covers work for the remainder of Fiscal Year 2018, from August 17, 2017 to June 30, 2018. The budget for Task 1 is not to exceed $24,000.

Task 2 will be to assess the funding alternatives for GSP development and implementation. The Geosyntec team will prepare an analysis of current and future funding alternatives to meet the GSA’s obligations under SGMA. The funding strategy could include a combination of various Federal or State programs, new legislative opportunities that are created on periodic basis, and a Prop 218/Prop 26 special district election process.  Task 2 covers work from August 17, 2017 to September 21, 2017. The estimated total fee for Task 2 is $8,000.

Board Supports Effort to Develop a Single GSP for the Tulare Lake Subbasin

At a special meeting on July 20, the South Fork Kings GSA Board of Directors approved entering into an agreement to facilitate a coordinated effort to develop and implement a single Groundwater Sustainability Plan for the Tulare Lake Subbasin. The interim agreement creates a cost-share schedule and basic decision-making structure for the selection of a consultant to prepare a grant application. It is intended to be modified or replaced by a more comprehensive and longer-term coordination agreement following grant award recommendations later this year. The signatories to the agreement are South Fork Kings GSA, Mid Kings GSA, El Rico GSA, Southwest Kings GSA, Tri-County Water Authority, and Alpaugh Irrigation District.

Other actions by the Board included the approval of a $265,250 budget for fiscal year 2018 and the selection of Geosyntec Consultants to perform technical engineering services. Budget expenses include engineering services, legal costs, Tulare Lake Subbasin coordination, and administrative services including outreach. Geosyntec will support the South Fork Kings with planning and implementing of a Proposition 218 and/or Proposition 26 elections; oversee, manage and coordinate preparation of a Groundwater Sustainability Plan; and other technical support including coordination with  adjacent groundwater sustainability agencies.

SFK Board Approves Contract with Hydrogeological Consultant

At their June 15 Board meeting, the South Fork Kings Groundwater Sustainability Agency Board Members approved a contract with Aegis Groundwater Consulting. Aegis will provide initial hydrogeologic support needed related to the scoping of a Groundwater Sustainability Plan and coordination with adjoining GSAs to determine data quality objectives, data collection and verification procedures and other technical aspects related to the development of a hydrologic model for the subbasin.

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