Colusa Subbasin Groundwater Sustainability Plan

Colusa Groundwater Authority | December 3rd, 2021

The purpose of this GSP is to characterize groundwater conditions in the Subbasin, evaluate and report on existing conditions relating to the six sustainability indicator

The purpose of this GSP is to characterize groundwater conditions in the Subbasin, evaluate and report on existing conditions relating to the six sustainability indicators, describe existing monitoring, 14 management programs and policies relating to groundwater resource use, document public outreach and communication, establish sustainability goals, and describe projects and management actions (PMAs) the GSAs will implement to achieve sustainable groundwater management within 20 years of implementing the GSP. Due to size, this file has been divided into 16 parts Part 1, Part 2, Part 3, Part 4, Part 5, Part 6, Part 7, Part 8, Part 9, Part 10, Part 11, Part 12, Part 13, Part 14, Part 15, Part 16

Comment on “Short-lived pause in Central California subsidence after heavy winter precipitation of 2017” by K. D. Murray and R. B. Lohman

American Association for the Advancement of Science (AAAS) | June 12th, 2019

In a study by Murray and Lohman (M&L), the authors suggest that remote sensing data are useful for monitoring land subsidence due to aquifer system compacti

In a study by Murray and Lohman (M&L), the authors suggest that remote sensing data are useful for monitoring land subsidence due to aquifer system compaction. We agree. To infer aquifer dynamics, we provide a more detailed and joint analysis of deformation and groundwater data. Investigating well data in the Tulare Basin, we find that groundwater levels stabilized before 2015 and show that M&L’s observed continued subsidence through July 2016 is likely caused by the delayed compaction of the aquitard. Our analysis suggests the observed 2017 transient uplift is not due to recharge of the aquifer system after heavy winter rainfall because it requires an unrealistic vertical hydraulic gradient nearly five orders of magnitude larger than that typical of Tulare Basin. We find that, regardless of the amount of rainfall, transient annual uplifts of ~3 cm occur in May to June. Using an elastic skeletal storage coefficient of 5 × 10−3, we link this ground uplift to annual groundwater level changes.

Community Perspectives on SGMA Implementation

University of California, Davis (UC Davis) | June 13th, 2019

The Sustainable Groundwater Management Act (SGMA) of 2014 represents a historic opportunity to achieve long-term sustainable groundwater management and protect th

The Sustainable Groundwater Management Act (SGMA) of 2014 represents a historic opportunity to achieve long-term sustainable groundwater management and protect the drinking water supplies of hundreds of small and rural low-income communities that rely on this shared resource, especially in the San Joaquin Valley. Prior research, however, indicates that few of these communities are represented in the Groundwater Sustainability Agencies (GSAs) formed to implement the new law. This raises questions about other forms of community involvement, and concerns about the extent to which small and rural drinking-water interests are being incorporated into the process. This report details the results of twenty-three interviews with thirty-one representatives of small, low-income communities who rely on groundwater for their drinking-water supplies. The findings suggest community stakeholders are highly interested in SGMA and desire to be involved in its implementation, which many deemed indispensable for the future of their communities. Many are actively participating or following the process, including by serving on boards and committees, attending meetings and workshops, and monitoring meeting minutes and agendas. The experience of small and rural communities with SGMA is predictably diverse. Some interviewees have had very positive experiences thus far and are hopeful about the ways SGMA could benefit their communities and regions in the future. Others have felt overlooked or intentionally excluded. Yet many similarities also arose across the interviews including six common challenges and concerns about SGMA implementation: 1. Resource constraints to participation: Lack of staff, small budgets, in-house experts and an inability to pay for outside services/support limited communities’ formal participation in GSA governance and attendance and involvement in SGMA meetings. 2. Accessibility: Additional factors limiting the accessibility of the SGMA process included day-time meetings, language barriers, the proliferation of board and committee meetings, and irregular and unclear meeting schedules and notices. 3. Transparency: A lack of transparency in GSA decision-making as well as limited access to the data and information being used to develop Groundwater Sustainability Plans (GSPs) were common concerns for interviewees. 4. Lack of formal representation: The relegation of communities to advisory, rather than decision-making, roles in the SGMA process was also a common concern. 5. Limited opportunities to provide meaningful input and feedback: Whether participating as a decision-maker, committee member or as a member of the public attending meetings, many were frustrated at the lack of opportunities to provide meaningful input into decisions or on draft documents due to short turnaround times, not being provided necessary background or materials, and limited opportunities for public comment and open discussion. 6. Lack of addressing drinking water interests and priorities: Overwhelmingly, interviewees reported that drinking water interests, especially water quality and domestic wells, were not part of their local SGMA conversations, leading many to be skeptical that SGMA would have drinking-water benefits. Best practices detailed by interviewees with particularly positive experiences and suggestions and recommendations from all of the interviewees, however, demonstrate ample opportunities to address these issues and increase the integration of drinking-water stakeholders and interests into sustainable groundwater management. Targeted efforts to reduce barriers to participation, improve communication and transparency, and promote diverse representation could go a long way to ensuring the “consideration” and “active involvement” of this important, historically marginalized, stakeholder group. For example, communities can educate their GSA about drinking-water priorities and the variety of regulations and requirements public water systems must comply with and coordinate with other small and rural communities to elevate and advocate for drinking water needs. GSAs should incorporate available public data into Groundwater Sustainability Plans (GSPs) while developing plans to fill data gaps, provide ample time for feedback on staggered and sequential GSP sections and streamline and increase interaction with stakeholders in meetings. State agencies should consider requiring or incentivizing collaborative community projects be included in GSPs, and community representation in GSP development and implementation as well as provide funding to support meaningful community involvement in all phases of SGMA implementation.

Comparing Domestic and Public-Supply Groundwater Quality in the Northern San Joaquin Valley, 2019: California GAMA Priority Basin Project

U.S. Geological Survey (USGS) | June 5th, 2023

Analysis of construction data for wells included in the comparative assessment indicated that, although depth to top of perforations are comparable for domestic and publi

Analysis of construction data for wells included in the comparative assessment indicated that, although depth to top of perforations are comparable for domestic and public-supply wells in the Northern San Joaquin Valley (median depth about 60 meters [m]), public-supply wells have longer perforation intervals and extend to deeper parts of the aquifer system (exceeding 120 m) than domestic wells that typically draw exclusively from the shallower aquifer system in the upper 80 m of unconsolidated sediments. Analysis of the vertical and lateral distribution of constituents of interest (nitrate, fumigants, and arsenic) across domestic- and public-supply aquifers indicated that nitrate is prevalent in shallow aquifers throughout the Northern San Joaquin Valley but is potentially diluted by mixing with deeper, older groundwater at long-screened public-supply wells. Fumigants were prevalent in areas of urban and agricultural land use in the western part of the Northern San Joaquin Valley, particularly in areas near Lodi, California, but 1,2,3-TCP was more widespread than DBCP and was detected in shallow and deeper parts of the aquifer system, potentially because of its recalcitrance in groundwater and ability to be detected at low concentrations. Arsenic was most prevalent in the western part of the Northern San Joaquin Valley with proximity to deltaic sediments and was detected at high RCs in wells tapping shallow and deep parts of the aquifer system.

Comparing Groundwater Quality in Public-Supply and Shallow Aquifers in the Monterey Bay and Salinas Valley Basins, California

U.S. Geological Survey (USGS) | December 17th, 2018

Groundwater quality in the Monterey–Salinas Valley Public-Supply and Shallow Aquifer Systems was investigated by the GAMA-PBP. The Monterey–Salinas Valley Pub

Groundwater quality in the Monterey–Salinas Valley Public-Supply and Shallow Aquifer Systems was investigated by the GAMA-PBP. The Monterey–Salinas Valley Public-Supply Aquifer System study unit (MS-PA) initially was assessed in 2005 (Kulongoski and Belitz, 2011). The Mon-terey–Salinas Valley Shallow Aquifer System study unit (MS-SA) was sampled in 2012–13 (Burton and Wright, 2018). The MS-PA and the MS-SA largely coincide areally; however, they represent different parts of the aquifer system vertically. The MS-PA examined deeper groundwater primarily used for public supply, whereas the MS-SA examined relatively shallow groundwater primarily used for domestic supply. The MS-SA was divided into four study areas. Three of these study areas combined (MS-SA3) were equivalent to the MS-PA study unit excluding a small sliver along the Carmel River. The fourth MS-SA study area, Highlands, is composed of the hills and mountains bordering the Salinas Valley. The MS-PA and the MS-SA study units have warm, dry summers and cool, moist winters. The average annual rainfall is 331 millimeters (mm; 13 inches, in.) with average annual temperatures of14 degrees Celsius (57 degrees Fahrenheit) in Salinas. The study units are drained by three main rivers and their tributaries: the Salinas, Pajaro, and San Lorenzo Rivers. Groundwater quality status and understanding assessments of the study units were based on data collected by the U.S. Geological Survey (USGS). In the MS-PA, additional inorganic data was obtained from the California State Water Resources Control BoardDivision of Drinking Water Public- Supply Well Water-Quality Database (Kulongoski and Belitz, 2011). A grid-based method to select wells was applied in both study units, which allows for an estimation of the proportions of the aquifer system with constituents at low, moderate, or high concentrations relative to regulatory and non- regulatory benchmarks for drinking-water quality established by the U.S. Environmental Protection Agency (EPA) or California State Water Resources Control Board Division of Drinking Water. The grid-based method provides statistically unbiased results and permits comparison of those results to other GAMA Priority Basin Project study areas (Belitz and others, 2010).

Comparing Local Groundwater Withdrawal Permitting Laws in the Southwest and California

Stanford University | October 13th, 2016

 For the first time in California’s history, the Sustainable Groundwater Management Act of 2014 (SGMA) aims to empower local agencies to sustainably manage the pumping

 For the first time in California’s history, the Sustainable Groundwater Management Act of 2014 (SGMA) aims to empower local agencies to sustainably manage the pumping of groundwater. A notable, but often unremarked, aspect of SGMA is that it provides Groundwater Sustainability Agencies (GSAs) with the power to adopt rules and regulations to establish “groundwater extraction allocations” (i.e., a permitting regime). California is the last of the seven southwest states — Arizona, California, Colorado, Nevada, New Mexico, Texas, and Utah — to introduce a permitting power, suggesting that the other southwestern states can inform GSAs looking to promote sustainability through the use of their new power to establish extraction allocations. 

Comprehensive Groundwater Cleanup Strategy for Historical Chromium Discharges from PG&E's Hinkley Compressor Station, San Bernardino County, Final Environmental Impact Report Volume I: Comments on Draft EIR and Responses

California State Water Resources Control Board (SWRCB) | April 20th, 2013

Click here for Volume II

Click here for Volume II

Concentrations for total dissolved solids, arsenic, boron, fluoride, and nitrite-nitrate for wells sampled in the Mojave Water Agency Management Area

U.S. Geological Survey (USGS) | July 1st, 2001

Concentrations for total dissolved solids, arsenic, boron, fluoride, and nitrite-nitrate for wells sampled in the Mojave Water Agency Management Area, California, 1991-97

U.S. Geological Survey (USGS) | January 31st, 2001

Conduct Airborne Electromagnetic Surveys

California Department of Water Resources (DWR) | July 15th, 2020