Tule Subbasin Probationary Hearing Draft Staff Report

California State Water Resources Control Board (SWRCB) | March 1st, 2024

The State Water Board recognizes that local public agencies in the Tule Subbasin significant efforts since the passage of SGMA to form groundwater sustainability agencies

The State Water Board recognizes that local public agencies in the Tule Subbasin significant efforts since the passage of SGMA to form groundwater sustainability agencies (GSAs) and then develop detailed technical and other information supporting the adoption and implementation of six groundwater sustainability plans (GSPs) for the subbasin. Despite those efforts, in January of 2022, DWR reviewed GSPs to determine if the GSPs met SGMA’s requirements and found it to be incomplete. Following revisions made by the GSAs in the subbasin, DWR reevaluated the GSPs in March of 2023, determined the GSPs to be inadequate, and referred the subbasin to the State Water Board, as required by SGMA. Consistent with SGMA, the State Water Board may now consider whether to designate the Tule Subbasin as a “probationary basin,” a term that is used in SGMA to describe a basin in the first stage of state intervention.

Tule Subbasin Probationary Hearing Final Staff Report

California State Water Resources Control Board (SWRCB) | August 30th, 2024

Board staff identified specific deficiencies in the Tule Subbasin 2022 GSPs and outlined potential corrective actions to address those specific deficiencies. • Chron

Board staff identified specific deficiencies in the Tule Subbasin 2022 GSPs and outlined potential corrective actions to address those specific deficiencies. • Chronic lowering of groundwater levels with insufficient management criteria. • Continued land subsidence (sinking). • Further degradation of groundwater quality. • Depletions of interconnected surface water.

Tuolumne Watershed Diversions without Hetch Hetchy Reservoir: Comparison of Interties to Cherry and Don Pedro Reservoirs

Environmental Defense Fund (EDF) | February 14th, 2005

Without storing water in Hetch Hetchy Valley, additional conveyance facilities could allow the San Francisco Public Utilities Commission to divert supplies from storage i

Without storing water in Hetch Hetchy Valley, additional conveyance facilities could allow the San Francisco Public Utilities Commission to divert supplies from storage in other Tuolumne River watershed reservoirs. The most obvious potential locations for additional conveyance are at Don Pedro Reservoir or at Holm Powerplant below Cherry Reservoir. Computer modeling, using a 73 year hydrologic record, indicates that either a Don Pedro Intertie or a Cherry Intertie would allow the SFPUC to deliver more than 95 percent of customer demand without diminishing system reliability. Some additional supplies would be needed in dry years to replace the loss of Hetch Hetchy Reservoir.

Turf Replacement Program Impacts on Households and Ratepayers: An Analysis for the City of Los Angeles

University of California, Los Angeles (UCLA) | September 30th, 2016

Ongoing severe drought and climate change continue to strain the Los Angeles region’s water supply and have forced the City to institute water savings goals (Garcetti,

Ongoing severe drought and climate change continue to strain the Los Angeles region’s water supply and have forced the City to institute water savings goals (Garcetti, 2014). Turf replacement programs, which aim to encourage residents to replace their lawn with less water intensive landscaping, may offer benefits as part of a larger package of conservation measures. More than half of residential water use is allocated for outdoor watering (approximately 54%) (Firestone, 2015). Outdoor water use is typically considered discretionary while indoor water use is generally considered essential, making outdoor water use a good target for conservation efforts. In order to encourage turf replacement, the city launched a turf replacement program in 2009. Commercial and residential customers can receive a rebate from the utility when they replace their lawns with less water intensive landscaping. Currently, the city is offering a rebate of $1.75 per sq. ft. up to 1,500 sq. ft. This report seeks to answer two questions regarding the turf replacement program. First, under what conditions does participation in the turf replacement program provide financial benefits to households? Second, is the turf replacement program a reasonably cost effective investment for utilities and ratepayers?

Turlock Subbasin Groundwater Sustainability Plan

West and East Turlock Subbasin Groundwater Sustainability Agencies | January 6th, 2022

The Turlock Subbasin Groundwater Sustainability Plan (GSP) was adopted January 6, 2022, and covers the Turlock Subbasin (5-22.03), which has been designated a high-priori

The Turlock Subbasin Groundwater Sustainability Plan (GSP) was adopted January 6, 2022, and covers the Turlock Subbasin (5-22.03), which has been designated a high-priority basin by the Department of Water Resources (DWR). The Turlock Subbasin covers about 348,160 acres (about 544 square miles) in the northern portion of the San Joaquin Valley Groundwater Basin. Subbasin boundaries are defined by the Tuolumne River on the north, the Merced River on the south, and the San Joaquin River on the west. The eastern boundary approximates the contact between Subbasin sediments and the crystalline basement rocks of the Sierra Nevada foothills. Two groundwater sustainability agencies (GSAs) have been formed in the Subbasin. The West Turlock Subbasin Groundwater Sustainability Agency (WTSGSA) is located in the western Subbasin and covers about 60 percent of the area. The East Turlock Subbasin Groundwater Sustainability Agency (ETSGSA) covers the remaining 40 percent of the Subbasin in the east. The two Subbasin GSAs have cooperatively developed one GSP, which covers the entire Turlock Subbasin as the Plan Area. The "Get Document" link will take you to the Department of Water Resources GSP page for Turlock Subbasin, where the 1,323-page GSP submitted by Turlock Groundwater may be downloaded. Or the file may be accessed in parts by clicking the links below. Click here for further links from Turlock Groundwater. Part 1, Part 2, Part 3, Part 4, Part 5, Part 6, Part 7, Part 8

Turlock Subbasin Groundwater Sustainability Plan (Revised)

West and East Turlock Subbasin Groundwater Sustainability Agencies | July 12th, 2024

The Turlock GSAs submitted the first version of the Turlock GSP to the Department of Water Resources (DWR) in January 2022. DWR determined the GSP to be incomplete in J

The Turlock GSAs submitted the first version of the Turlock GSP to the Department of Water Resources (DWR) in January 2022. DWR determined the GSP to be incomplete in January of 2024 (DWR, 2024) and identified two deficiencies. The first of these involves provision of sufficient information (namely, analysis of potential impacts on wells) to support the selection of sustainable management criteria for chronic lowering of groundwater levels. The second involves the provision of sufficient details on the projects and management actions to mitigate overdraft in the Subbasin and to provide a feasible path to achieve sustainability. Corrective actions are incorporated into this revised July 16, 2024 GSP for resubmittal to DWR. This does not represent a GSP update, which is slated for 2027. The revised GSP was adopted by the GSAs on July 11, 2024 pursuant to 23 CCR § 355.2(e)(2)(A).

Twentieth-century shifts in forest structure in California: Denser forests, smaller trees, and increased dominance of oaks

National Academy of Sciences (NAS) | January 20th, 2015

Twenty-first Annual Report of the Mojave Basin Area Watermaster

Mojave Basin Area Watermaster | May 1st, 2015

Twenty-first century hydroclimate: A continually changing baseline, with more frequent extremes

National Academy of Sciences (NAS) | March 14th, 2022

Variability in hydroclimate impacts natural and human systems worldwide. In particular, both decadal variability and extreme precipitation events have substantial effect

Variability in hydroclimate impacts natural and human systems worldwide. In particular, both decadal variability and extreme precipitation events have substantial effects and are anticipated to be strongly influenced by climate change. From a practical perspective, these impacts will be felt relative to the continuously evolving background climate. Removing the underlying forced trend is therefore necessary to assess the relative impacts, but to date, the small size of most climate-model ensembles has made it difficult to do this. Here we use an archive of large ensembles run under a high-emissions scenario to determine how decadal “megadrought” and “megapluvial” events—and shorter-term precipitation extremes—will vary relative to that changing baseline. When the trend is retained, mean state changes dominate: In fact, soil moisture changes are so large in some regions that conditions that would be considered a megadrought or pluvial event today are projected to become average. Time-of-emergence calculations suggest that in some regions including Europe and western North America, this shift may have already taken place and could be imminent elsewhere: Emergence of drought/pluvial conditions occurs over 61% of the global land surface (excluding Antarctica) by 2080. Relative to the changing baseline, megadrought-/megapluvial risk either will not change or is slightly reduced. However, the increased frequency and intensity of both extreme wet and dry precipitation events will likely present adaptation challenges beyond anything currently experienced. In many regions, resilience against future hazards will require adapting to an ever-changing “normal,” characterized by unprecedented aridification/wetting punctuated by more severe extremes.

Twenty-First Century Levee Overtopping Projections from InSAR-derived subsidence rates in the Sacramento-San Joaquin Delta: 2006–2010

California Energy Commission (CEC) | July 31st, 2012

To provide an updated synoptic assessment of vertical land motion rates in the Sacramento-San Joaquin Delta, the research team performed synthetic aperture radar interfer

To provide an updated synoptic assessment of vertical land motion rates in the Sacramento-San Joaquin Delta, the research team performed synthetic aperture radar interferometry (InSAR) on 35 radar scenes from the Envisat platform acquired from 2006–2010. The study used contemporaneously collected continuous global positioning system data to tie the InSAR results to an absolute reference frame. In accord with the researchers’ previous study from 1995–2000 (VLM00), the new results (VLM10) demonstrate general subsidence of the Delta with respect to its margins. The average rates of ~1-2 millimeters per year (mm/yr) are slightly lower than the ~3-5mm/yr rates from 1995–2000. An unexpected finding is the uplift associated with Roberts Island, in the Delta’s southeastern sector.  The time- and space-varying differences between the two solutions (VLM00 and VLM10) highlights the need to develop a physical model for the Delta. The study used the updated ground-motion rate map and the most current twenty-first century sea-level rise predictions to project when Delta levees will subside below high-water design thresholds. The study showed that the time period between 2050–2075 is a critical time period, when levees will start to fall below design thresholds, and by 2100 most Delta levees will probably do so.