Groundwater Sustainability Plan for the Oxnard Subbasin

Fox Canyon Groundwater Management Agency (FCGMA) | December 13th, 2019

The Fox Canyon Groundwater Management Agency (FCGMA, or the Agency) has developed this Groundwater Sustainability Plan (GSP) for the Oxnard Subbasin (Subbasin; DWR Basin

The Fox Canyon Groundwater Management Agency (FCGMA, or the Agency) has developed this Groundwater Sustainability Plan (GSP) for the Oxnard Subbasin (Subbasin; DWR Basin 4-004.02) of the Santa Clara River Valley Groundwater Basin (DWR Basin 4-004), in compliance with the 2014 Sustainable Groundwater Management Act (SGMA; California Water Code, Section 10720 et seq.). The purpose of this GSP is to define the conditions under which the groundwater resources of the entire Oxnard Subbasin, which support agricultural, municipal and industrial, and environmental uses, will be managed sustainably in the future. Historical groundwater production has resulted in seawater intrusion in the five primary aquifers of the Subbasin. These aquifers have been divided into an Upper Aquifer System, which comprises the Oxnard and Mugu Aquifers, and a Lower Aquifer System, which comprises the Hueneme, Fox Canyon, and Grimes Canyon Aquifers. The average rate of groundwater production from the Upper Aquifer System between 2015 and 2017 was approximately 40,000 acre-feet per year (AFY). The average production from the Lower Aquifer System between 2015 and 2017 was approximately 29,000 AFY. Numerical groundwater simulations indicate that if these production rates were carried into the future, seawater intrusion would continue in the Subbasin and the area currently impacted by concentrations of chloride greater than 500 milligrams per liter would grow. The landward extent of this area is referred to as the saline water impact front. Combinations of projects and management actions were explored to estimate the rate of groundwater production that would prevent future expansion of the area of the Subbasin currently impacted by concentrations of chloride greater than 500 milligrams per liter. This rate of groundwater production is referred to as the sustainable yield. With the currently available projects and management actions, the sustainable yield of the Upper Aquifer System, was calculated to be approximately 32,000 AFY, with an uncertainty of ± 4,100 to 6,000 AFY. The sustainable yield of the Lower Aquifer System was calculated to be approximately 7,000 AFY, with an uncertainty of ± 2,300 to 3,600 AFY. Adoption of this GSP represents the first step in achieving groundwater sustainability within the Oxnard Subbasin by 2040, as required by SGMA. Evaluation of this GSP is required at a minimum of every 5 years following submittal to the California Department of Water Resources (DWR). As part of the 5-year evaluation process, the sustainable yield for each aquifer system will be refined and adjusted. These refinements will be based on new data, additional studies undertaken to fill data gaps, and groundwater modeling. Refinements and adjustments will also be made to the minimum threshold water levels developed to avoid undesirable results, the measurable objective water levels that account for the need to continue groundwater production during drought cycles and the associated interim milestones to help gauge progress toward sustainability over the next 20 years. In order to minimize the pumping reductions required to achieve sustainable management of the Subbasin, investment in large-scale projects to increase water supply, provide the infrastructure to redistribute pumping, and/or directly control seawater intrusion should be investigated. Basin optimization studies, groundwater modeling, and project feasibility studies will be conducted over the next 5 years to explore practicable processes and approaches to increasing the sustainable yield of the Oxnard Subbasin.

Groundwater Sustainability Plan for the Pleasant Valley Basin

Fox Canyon Groundwater Management Agency (FCGMA) | December 13th, 2019

The Fox Canyon Groundwater Management Agency (FCGMA, or the Agency) has developed this Groundwater Sustainability Plan (GSP) for the Pleasant Valley Basin (PVB; DWR Basi

The Fox Canyon Groundwater Management Agency (FCGMA, or the Agency) has developed this Groundwater Sustainability Plan (GSP) for the Pleasant Valley Basin (PVB; DWR Basin 4-006), in compliance with the 2014 Sustainable Groundwater Management Act (SGMA) (California Water Code, Section 10720 et seq.). FCGMA is one of three Groundwater Sustainability Agencies (GSAs) in the PVB. The other two GSAs are the Camrosa Water District–Pleasant Valley GSA and the Pleasant Valley Outlying Areas GSA. This GSP is the sole GSP prepared for the PVB, and covers the entire PVB, including all areas of the PVB outside of FCGMA’s jurisdiction. The purpose of this GSP is to define the conditions under which the groundwater resources of the entire PVB, which support agricultural, municipal and industrial, and environmental uses, will be managed sustainably in the future. The PVB shares a boundary and is in hydraulic communication with Oxnard Subbasin (Subbasin; DWR Basin 4-004.02) to the west. The boundary between the PVB and the Oxnard Subbasin is associated with a change in character of recent and older alluvial deposits. In the PVB, these deposits are finer grained and are, in general, less suitable for groundwater production than the coarser-grained sediments of the same age in the Oxnard Subbasin. There is no corresponding change in character in the deeper aquifers, including the Fox Canyon Aquifer, which are continuous across the boundary between the PVB and the Oxnard Subbasin. Groundwater production from wells on either side of the boundary between the PVB and the Oxnard Subbasin influences groundwater elevations and the direction of groundwater flow across this boundary. Historical groundwater production from the PVB and Oxnard Subbasin combined has resulted in seawater intrusion in the aquifers of the Subbasin. In the PVB, the average rate of groundwater production between 2015 and 2017 was approximately 13,200 acre-feet per year (AFY). In 2015, approximately 53% of the production from the Lower Aquifer System, which comprises the Hueneme, Fox Canyon, and Grimes Canyon Aquifers, and 47% of the production from the Upper Aquifer System, which comprises the older alluvium in the PVB, and the Oxnard and Mugu Aquifers in the Oxnard Subbasin. Numerical groundwater simulations indicate that if these production rates were carried into the future, groundwater elevations in the PVB would not recover during multi-year cycles of drought and recovery, and seawater intrusion would continue in the Oxnard Subbasin. The landward extent of the area in the Subbasin currently impacted by concentrations of chloride greater than 500 milligrams per liter is referred to as the “saline water impact front.” Combinations of projects and management actions were explored to estimate the rate of groundwater production that would allow groundwater elevations in the PVB to recover during multi-year cycles of drought and recovery, and prevent future landward migration of the saline water impact front. This rate of groundwater production is referred to as the sustainable yield. With the currently available projects and management actions, the sustainable yield of the PVB was estimated to be approximately 11,600 AFY, with an uncertainty of ± 1,200 AFY. At the upper bound of the uncertainty estimate (12,600 AFY), the estimated sustainable yield of the PVB is 600 AFY lower than the 2015–2017 average production rate. Adoption of this GSP represents the first step in achieving groundwater sustainability within the PVB by 2040, as required by SGMA. Evaluation of this GSP is required at a minimum of every 5 years following submittal to the California Department of Water Resources (DWR). As part of the 5-year evaluation process, the sustainable yield will be refined and adjusted. These refinements will be based on new data, additional studies undertaken to fill data gaps, and groundwater modeling. Refinements and adjustments will also be made to the minimum threshold groundwater levels developed to avoid undesirable results, the measurable objective groundwater levels that account for the need to continue groundwater production during drought cycles and the associated interim milestones to help gauge progress toward sustainability over the next 20 years. In order to minimize the pumping reductions required to achieve sustainable management of the PVB, investment in projects to increase water supply, provide the infrastructure to redistribute pumping, and/or directly control seawater intrusion in the Oxnard Subbasin should be investigated. Inter-basin optimization studies, groundwater modeling, and project feasibility studies are recommended over the next 5 years to explore practicable processes and approaches to increasing the sustainable yield of the PVB. Due to size, this file has been divided. Part 1, Part 2, Part 3, Part 4, Part 5, Part 6

Groundwater Sustainability Plan for the San Joaquin River Exchange Contractors Groundwater Sustainability Plan (GSP) Group in the Delta-Mendota Subbasin

San Joaquin River Exchange Contractors GSA (SJREC GSA) | December 13th, 2019

Groundwater Sustainability Plan for the San Joaquin River Exchange Contractors GSP Group in the Delta-Mendota Subbasin (5-022.07)

San Joaquin River Exchange Contractors Water Authority (SJRECWA) | June 30th, 2022

The GSP was adopted by the SJREC GSA on December 13, 2019. The GSP has been amended in response to the January 21, 2022 DWR Determination letter to Delta-Mendota Subbasin

The GSP was adopted by the SJREC GSA on December 13, 2019. The GSP has been amended in response to the January 21, 2022 DWR Determination letter to Delta-Mendota Subbasin’s Point of Contact that included evaluation of the San Joaquin River GSA’s Groundwater Sustainability Plan (GSP). The amended plan was adopted by the SJRECGSA Board on July 5, 2022. On March 2nd, 2023, the Department of Water Resources announced decisions for Groundwater Sustainability Plans (GSPs), finding that numerous subbasins were found to be inadequate. One of these subbasins—the Delta-Mendota Subbasin in San Joaquin, Stanislaus, Merced, Fresno, Madera, and San Benito counties—includes a region for which the Exchange Contractors are responsible for developing the GSP. Due to size, this file has been divided. Part 1, Part 2, Part 3, Part 4, Part 5, Part 6, Part 7, Part 8

Groundwater Sustainability Plan Greater Kaweah Groundwater Sustainability Agency

Greater Kaweah Groundwater Sustainability Agency (GKGSA) | January 22nd, 2020

Groundwater Sustainability Plan, County of Fresno Groundwater Sustainability Agency, Management Area A and Management Area B, Delta-Mendota Subbasin

County of Fresno | January 23rd, 2020

Groundwater Sustainability Plan, Olcese Groundwater Sustainability Agency, Kern County Subbasin

Olcese Groundwater Sustainability Agency | January 30th, 2020

Groundwater: The Water-Budget Myth

National Academy of Sciences (NAS) | June 1st, 1982

Water-resource scientists are concerned that some basic principles are being overlooked by water managers. Rather than discuss the scope of groundwater hydrolog

Water-resource scientists are concerned that some basic principles are being overlooked by water managers. Rather than discuss the scope of groundwater hydrology, we have chosen to focus on a common misconception to illustrate the point. Perhaps the most common misconception in groundwater hydrology is that a water budget of an area determines the magnitude of possible groundwater development. Several well-known hydrologists have addressed this misconception and attempted to dispel it. Somehow, though, it persists and continues to color decisions by the water-management community. The laws governing the development of groundwater in Nevada as well as several other states are based on the idea that pumping within a groundwater basin shall not exceed the recharge. It is the intent of this paper to re-examine the issue.

Growing impact of wildfire on western US water supply

National Academy of Sciences (NAS) | February 22nd, 2022

Streamflow often increases after fire, but the persistence of this effect and its importance to present and future regional water resources are unclear. This paper addres

Streamflow often increases after fire, but the persistence of this effect and its importance to present and future regional water resources are unclear. This paper addresses these knowledge gaps for the western United States (WUS), where annual forest fire area increased by more than 1,100% during 1984 to 2020. Among 72 forested basins across the WUS that burned between 1984 and 2019, the multibasin mean streamflow was significantly elevated by 0.19 SDs (P < 0.01) for an average of 6 water years postfire, compared to the range of results expected from climate alone. Significance is assessed by comparing prefire and postfire streamflow responses to climate and also to streamflow among 107 control basins that experienced little to no wildfire during the study period. The streamflow response scales with fire extent: among the 29 basins where >20% of forest area burned in a year, streamflow over the first 6 water years postfire increased by a multibasin average of 0.38 SDs, or 30%. Postfire streamflow increases were significant in all four seasons. Historical fire–climate relationships combined with climate model projections suggest that 2021 to 2050 will see repeated years when climate is more fire-conducive than in 2020, the year currently holding the modern record for WUS forest area burned. These findings center on relatively small, minimally managed basins, but our results suggest that burned areas will grow enough over the next 3 decades to enhance streamflow at regional scales. Wildfire is an emerging driver of runoff change that will increasingly alter climate impacts on water supplies and runoff-related risks.

Guide for Developing Onsite Water Systems to Support Regional Water Resilience

Pacific Institute | January 26th, 2023

Across the United States, urban communities face growing water challenges, from water scarcity to flooding, pollution, aging water infrastructure, and more. These challen

Across the United States, urban communities face growing water challenges, from water scarcity to flooding, pollution, aging water infrastructure, and more. These challenges present risks, but also an opportunity to rethink how we manage water, including adopting circular approaches in new buildings that reduce their water footprint and improve urban water resilience. Onsite water systems, for example, collect, treat, and reuse water from onsite sources, including wastewater, rainwater, and stormwater, for non-potable water uses like toilet flushing, outdoor irrigation, and cooling. Onsite water systems have the potential to provide multiple benefits for a site, water and wastewater systems, ecosystems, and communities. They can, for example, help companies mitigate water- related risks, like water shortages that threaten to disrupt business operations, and support corporate water stewardship goals. For communities, onsite water systems can enhance water supply reliability, improve water quality, reduce localized flooding, and increase urban green space. The realization and magnitude of benefits will vary with the type of system, scale of adoption, and other context-specific factors. This guide helps site developers consider how onsite water systems can be planned, designed, and operated to provide multiple benefits, and contribute to planning and designing onsite water systems that advance water resilience, support equity, support the environment, and protect public health at the site, water system, and community scales. For each of these outcomes, the guide provides sample questions to consider, stakeholders to engage, resources to examine, and analyses to perform.