Fresno Irrigation District and SGMA

FID's efforts toward groundwater sustainability

SGMA

SGMA (pronounced sig-ma), or the Sustainable Groundwater Management Act, was signed into law by former California Governor Jerry Brown in 2014. SGMA consists of three legislative bills: SB 1168, SB 1319, and AB 1739 which together serve the purpose of achieving sustainability of groundwater resources in California.

Local Groundwater Sustainability Agencies (GSAs) were identified as the best path forward to managing and mitigating groundwater at the local level. SGMA requires the creation of groundwater sustainability plans (GSPs) to be developed by these local agencies in coordination with adjacent GSAs for the sustainability of the underground aquifer. All groundwater basins desginated as high and medium priority must be managed by 2022, or by 2020 if the basin is critically overdrafted.

Why is it important?

SGMA was established in order to stop critical groundwater overdraft and bring groundwater basins into balanced levels of pumping and recharge. By implementing SGMA, water districts and Groundwater Sustainability Agencies are able to achieve sustainability and increase water supply.


Six Key Indicators

These are the six key indicators of an unsustainable sub-basin developed by the California Department of Water Resources and the State Water Resources Control Board. SGMA was designed to address these six key indicators to reach sustainability. While many other GSAs need to worry about seawater intrusion or land subsidence, those issues are not a primary concern in the North Kings GSA.

Lowering Groundwater Levels

Groundwater level decline is of the most concern within FID and NKGSA. FID and NKGSA are actively addressing this issue through a coordinated strategy of basin construction, on-farm recharge, and irrigation method versatility.

Reduction of Storage

The reduction of groundwater storage indicator is similar to the lowering groundwater level indicator, but at a subbasin-wide scale. For instance, this graphic shows parts of the NKGSA recording a 40-60' drop in the water table, while other parts of the GSA are actually seeing a rise in water level.

SGMA requires groundwater storage levels to be sustainable at the subbasin level. The seven GSAs of the Kings Subbasin must work together to achieve this goal.

Degraded Groundwater Quality

Pollutants can enter the aquifer from various agricultural, industrial, and residential sources. SGMA requires that each GSA work to keep those pollutants in groundwater below maximum contaminant level (MCL) thresholds.

Land Subsidence

Although not as prevalent within the Fresno Irrigation District and North Kings GSA, land subsidence has become a major issue for much of the San Joaquin Valley.

Land subsidence is caused by the excessive pumping of groundwater from certain types of fine-grained sediments. When the water filling the pores within these sediments is removed, the sediments begin to compact in on itself.

This iconic image of Dr. Joseph F. Poland shows a more extreme example of land subsidence. This photograph was taken southwest of Mendota, CA.


Development of GSAs

SGMA requires the development of Groundwater Sustainability Agencies (GSAs) to act as a new structure for managing groundwater resources by local agencies. The State of California needed to create agencies that could coordinate at the local level to achieve sustainability. Geographic barriers, hydrogeological conditions, and political boundaries had to be taken into consideration to define the new GSA boundaries.

The California Department of Water Resources (DWR) identified 515 groundwater basins and subbasins. North Kings GSA operates within the Kings Subbasin, an area over 1,500 square miles.

The Kings Subbasin is generally defined as the region in California's San Joaquin Valley that spans from the San Joaquin River to the north, and the Kings River to the south. This subbasin receives the majority of its groundwater via precipitation and runoff from the Kings River watershed.

The Kings Subbasin, like many other subbasins, were further divided into smaller GSAs. The North Kings GSA is authorized under SGMA to develop, adopt, and implement a Groundwater Sustainability Plan (GSP) for the sustainable management of groundwater in a portion of the Kings Subbasin.


Kings Subbasin GSAs

The North Kings GSA is one of seven GSAs in the Kings Subbasin, and consists of 10 member agencies who work in coordination with each other to accomplish the SGMA mandated requirements.

North Kings GSA Special Districts

Joint Powers Agreement (JPA) members

  • Fresno Irrigation District
  • Fresno Metropolitan Flood Control District
  • Bakman Water Company
  • Garfield Water District
  • International Water District

Other entities within NKGSA

  • Malaga County Water District
  • Pinedale County Water District

Fresno Irrigation District (FID) is the largest member of the North Kings GSA. FID serves approximately 247,000 of the 310,000 acres (~80%) of the North Kings GSA.

North Kings GSA Agencies

JPA Members

  • City of Fresno
  • City of Clovis
  • City of Kerman
  • Biola Community Service District
  • County of Fresno (not shown for clarity purposes)

North Kings GSA's Role in SGMA

The sustainability goal of the Kings Subbasin and the North Kings GSA is to ensure that by 2040 the subbasin is being managed to maintain a reliable water supply for current and future beneficial uses without experiencing undesirable results. This goal will be met by balancing water demand with available water supply to stabilize declining groundwater levels without significantly and unreasonably impacting water quality, land subsidence, or interconnected surface water. The goal of the subbasin is to correct and end the long-term trend of a declining water table understanding that water levels will fluctuate based on the season, hydrologic cycle, and changing groundwater demands within the subbasin and its proximity.

Conditions within the North Kings GSA will be considered sustainable when:

  • The subbasin is continuously operated within its sustainable yield.
  • The current rate of decline of the groundwater table within the subbasin monitoring network's indicator wells has been corrected and the multi-year trend of water elevations in these wells has been stabilized.
  • Groundwater management activities prevent undesirable results to groundwater level, groundwater storage, groundwater quality, land subsidence and interconnected surface water.

NKGSA illustration depicting setting a measurable objective for groundwater levels at indicator wells with enough room for operational flexibility in case of a severe drought.

Under SGMA, GSAs must work to prevent the groundwater level decline from reaching a consensus minimum threshold for each well included in the Groundwater Sustainability Plan's well monitoring network. This will be done through incremental rates of mitigation that will gradually flatten the decline. This is known as the "Glidepath to Sustainability".


Fresno Irrigation District's Role in SGMA

FID Diversions

FID diversions vary by annual weather conditions, but average roughly 500,000 acre-feet of water into the North Kings GSA every year. FID diversions are used primarily for agricultural irrigation, but has seen expanded use by the cities of Fresno and Clovis through their surface water treatment plants to provide clean drinking water to over 600,000 residents.

Pine Flat Dam - Photo taken in May 1967

Most of the surface water diverted into the North Kings GSA comes from the Kings River release just downstream of the Pine Flat Reservoir. FID's Fresno and Gould canals have their headgates on the Kings River. These canals have been diverting water to the Fresno region since the late 19th century. The Fresno and Gould canals branch off into 680 miles of canals that distribute surface water to over 375 square miles of FID service area.

FID Basins

FID’s sustainability efforts include adding 150 acres of additional recharge basins since 2020 when the North Kings GSA’s GSP was submitted. There are plans to add another 420 acres of recharge basins to capture up to an additional 30,000 acre-feet of floodwaters in 16 projects identified by FID in the North Kings GSA’s GSP project list.

FID uses the following criteria for basin site planning:

  • Connection to FID's major distribution canals and flood channels
  • Proximity to disadvantaged communities (DACs) which would benefit from the water level and water quality improvements
  • Areas that have seen groundwater level decline
  • UC Davis' Soil Agricultural Groundwater Banking Index (SAGBI) scores  https://casoilresource.lawr.ucdavis.edu/sagbi/ 
  • Operational flexibility + canal regulation

Savory Pond Basin Construction


Existing Recharge Basins and Groundwater Conditions

Depth to groundwater in the fall of 2021. Contours were created from FID and city monitoring well data.


Basin Construction (2020-2022)


FID's Wagner Basin Progress

During the spring and summer of 2022, FID engineering staff worked with contractors to excavate approximately 360,000 cubic yards of soil. This soil was used to help construct the Veterans Boulevard overpass in northwest Fresno.

Fresno Irrigation District's 60-Acre Wagner Basin. February 2022 - September 2022


Challenges Going Forward

FID's GM Bill Stretch at the Savory Basin ribbon cutting ceremony

New Recharge Basins

As the primary supplier of surface water to the communities and growers within the North Kings Groundwater Sustainability Agency, Fresno Irrigation District has taken its role seriously. With Board of Directors' support and approval, FID's General Manager, Bill Stretch, has committed to the significant expansion of our strategically placed recharge basins.

In December of 2021, Bill Stretch set a goal for FID to acquire 420 acres of land by 2023, and is on track to achieve this ahead of schedule. This land will be used to construct at least ten new recharge basins capable of bringing in flood waters during wet years, and storing it in our aquifer for future droughts.

Precipitation

Historically, the lands within the Fresno Irrigation District average only around 11" of precipitation per year  [1] . However, the Kings River watershed (outlined in red) averages nearly 39" of precipitation. Almost all water agencies on the eastern side of the San Joaquin Valley are reliant upon precipitation falling upon the Sierra Nevada mountain range. Typically, much of this precipitation falls in the winter as snow, and is gradually released as snowmelt downstream to reservoirs such as Pine Flat Reservoir.

FID relies upon the Kings River watershed snowpack and the Pine Flat Reservoir for storage. The Pine Flat Reservoir can hold around 1,000,000 acre-feet at any given time, which can be much less than the total Kings River watershed snowmelt and precipitation runoff during average to wet years. In an ideal situation, the watershed would receive a significant snowpack in the winter and a cool spring to follow. This enables a slow accumulation of snowmelt that can be released in a controlled manner for the late spring and summer months. This scenario is not always the case, which is why basin construction for floodwater release has been such a priority for FID.

1981-2010 30-Year Normals for Kings River Watershed Precipitation. Created by K. Mitchell

Droughts

Droughts have always been a part of California history. The last "Wet Cycle" of Kings River runoff was the water years 1994-95 to 1997-98. 24 years have passed since the last continuous wet cycle. Droughts have been frequent and severe in the 21st century.

California water agencies must plan ahead to take advantage of the wet years that are unpredictably mixed in. Basins need to be built, on-farm recharge needs to be planned, and floodwater routing needs to be available for water years like 2016-17 and 2018-19.

Kings River Runoff. Averages are based off of 127 years of Kings River runoff data. Click to enlarge.

Boundary Flows

Within the Kings Subbasin, groundwater moves to regions with lower groundwater elevations, known as boundary flow.  Without boundary flows, the groundwater levels within the NKGSA would be higher than they are today.

It is important to note that the boundary flow from NKGSA to the McMullin Area GSA is being further evaluated to better quantify the boundary flows.  FID and NKGSA intend to fully recapture all imported and developed water within its boundaries.


How can I help achieve water sustainability?

Growers

  • When converting to micro irrigation systems, maintain the ability to use flood irrigation during wet years.
  • Use flood irrigation in wetter years instead of drip.
  • When FID has excess water available, take delivery and spread for on-farm recharge or storage in a local, private pond.
  • Contact FID to explore options for using drip or micro irrigation systems directly off an FID canal during drier years.
  • There are still data gaps in the NKGSA's indicator well network. Contact the North Kings GSA Executive Director Kassy Chauhan at kchauhan@fresnoirrigation.com if you would like to volunteer your well to be an indicator well for semi-annual measurements.

Additional Resources:

North Kings GSA Groundwater Sustainability Plan  https://northkingsgsa.org/groundwater-sustainability-plan/ 

Fresno Irrigation District Groundwater & Sustainability  https://www.fresnoirrigation.com/sgma 

1981-2010 30-Year Normals for Kings River Watershed Precipitation. Created by K. Mitchell

Kings River Runoff. Averages are based off of 127 years of Kings River runoff data. Click to enlarge.

NKGSA illustration depicting setting a measurable objective for groundwater levels at indicator wells with enough room for operational flexibility in case of a severe drought.

Pine Flat Dam - Photo taken in May 1967

FID's GM Bill Stretch at the Savory Basin ribbon cutting ceremony