Nearly 275 attendees joined the Kaweah Subbasin for State of the Subbasin, where the East Kaweah, Mid-Kaweah, and Greater Kaweah GSA managers and their technical consultants presented on the subbasin’s probationary status, Sustainable Groundwater Management Act (SGMA) implementation priorities, and growers’ role in implementation.
The presentation was given by GSA managers, staff, and technical consultants.
- Mike Hagman, Executive Director, East Kaweah GSA
- Mark Larsen, General Manager, Greater Kaweah GSA
- Aaron Fukuda, Interim General Manager, Mid-Kaweah GSA
- Diana Zegarra, Assistant Water Resources Engineer, Tulare Irrigation District and Mid-Kaweah GSA
- Trey Driscoll, Principal Hydrogeologist, INTERA
- Derrik Williams, Principal Hydrogeologist, Montgomery & Associates
- Matt Klinchuch, Principal Engineer, Provost & Pritchard
Mark opened the event providing background on SGMA, and giving an update on the progress made since last year’s subbasin event. He educated attendees on the “technical core teams” put in place to address Subbasin hydrogeologic challenges. The technical core teams include the following priorities outlined in the revised GSPs:
- Groundwater levels
- Groundwater quality
- Interconnected surface water
- Land subsidence
- Mitigation
- Small community well
- Groundwater accounting framework
- Well inventory
- Well registration
Technical consultants Trey, Derrik, and Matt provided further detail about groundwater levels, water quality, and land subsidence.
Groundwater Quality
Trey presented on the Subbasin’s new groundwater quality monitoring effort, a Subbasin-wide seasonal water sampling program at several monitoring sites. The sampling is a coordinated partnership with the Kaweah Water Foundation. There is an expanded network of over 70 contaminants, or “constituents of concerns,” tested. Trey also mentioned the Exceedance Policy, which helps identify which monitoring result exceedances fall within the scope of SGMA. From this Exceedance Policy, the Subbasin will prepare an annual Groundwater Quality Report, with the first completed this past year. In the future, the Subbasin has plans to mail shorter letters to households near monitoring sites that alert them of elevated contaminant levels.
Land Subsidence
Derrik educated stakeholders on subsidence, the sinking of the land surface. GSAs are responsible under SGMA for avoiding or minimizing subsidence due to groundwater pumping. The State is most concerned with how land subsidence will impact infrastructure or land use. To address this, the Kaweah Subbasin developed a subsidence mitigation plan, compliant with the State’s Best Management Practices for subsidence. The plan requires rapid and significant actions by the Kaweah Subbasin and neighboring subbasins, with some solutions including increased recharge efforts, and moving pumping to shallower aquifers.
Groundwater Levels
Although groundwater level trends have improved since the inception of SGMA, levels are expected to decline until the subbasin reaches sustainability in 2040. Matt presented that groundwater levels have a ripple effect on many other issues, including groundwater quality, groundwater storage, subsidence, and depleted interconnected surface water. Managing groundwater levels is challenging because there is uncertainty about how many wells are in each GSA, and which aquifers they are pumping from. It is also challenging to implement new policies because it may require new investments or changes in local business practices. The Subbasin is working to address these challenges by monitoring groundwater levels during seasonal sampling via monitoring sites, filling data gaps through well inventory, and managing groundwater levels through allocations and recharge projects.
There has been major progress toward local groundwater management, but the work continues as immediate action is taken to mitigate negative impacts of declining groundwater levels and move fully toward being a sustainable subbasin by 2040.
The Kaweah Subbasin values gathering as a coordinated subbasin to update landowners and could not have done this event without its engaged stakeholders.
All event resources, including PowerPoint slides, photos, and the event recording here.