Category: Land Use Planning and Management

Replenishing Groundwater in the San Joaquin Valley

February 6, 2023 No Comments

The San Joaquin Valley—which has the biggest imbalance between groundwater pumping and replenishment in the state—is ground zero for implementing the 2014 Sustainable Groundwater Management Act (SGMA). Expanding groundwater recharge could help local water users bring their basins into balance and make a dent in the long-term deficit of nearly 2 million acre-feet per year.

The experience with recharge in 2017―the first wet year since the enactment of SGMA―offers valuable insights in how to expand recharge. A survey of valley water districts’ current recharge efforts revealed strong interest in the practice, and a number of constraints.

Building Multi-Benefit Recharge Basins

February 6, 2023 No Comments

As California faces an unpredictable water future, policy makers and water managers across the state are seeking solutions to build resilience into our water supply system. Groundwater recharge is an excellent tool to replenish depleted aquifers and bank water for future use. In addition to helping water managers balance their water budget, groundwater recharge also provides an opportunity to create habitat for wildlife. This guide highlights recharge basin management strategies that create wildlife habitat and provide operational benefits to basin managers.

Groundwater Resource Hub

February 2, 2023 No Comments

The purpose of the Groundwater Resource Hub is to help local agencies achieve sustainable groundwater management by providing the science and tools needed to help address nature’s water needs. Over time, the goal is to improve statewide and local understanding of nature’s groundwater needs to reduce uncertainties and therefore enhance sustainable groundwater management.

Groundwater dependent ecosystems (GDEs) are plant and animal communities that require groundwater to meet some or all of their water needs. California is home to a diverse range of GDEs including palm oases in the Sonoran Desert, hot springs in the Mojave Desert, seasonal wetlands in the Central Valley, perennial riparian forests along the Sacramento and San Joaquin rivers, and estuaries along the coast and in the Delta. These ecosystems rely on groundwater in California’s semi-arid climate, especially during dry summers and periods of drought. GDEs provide important benefits to California including habitat for animals, water supply, water purification, flood mitigation, erosion control, recreational opportunities and general enjoyment of California’s natural landscape.

Management Considerations for Protecting Groundwater Quality Under Agricultural Managed Aquifer Recharge

February 2, 2023 No Comments

Unsustainable groundwater use in California – due in large part to historical over-pumping of aquifer systems, growing reliance on groundwater to meet irrigation and urban water demands, and increasing frequency of drought – affects all water users and threatens agricultural viability into the future, but has disproportionately impacted disadvantaged communities and jeopardizes their access to safe, clean and affordable water. To secure the availability of groundwater for all uses, the state enacted the Sustainable Groundwater Management Act (SGMA) in 2014. Groundwater Sustainability Agencies (GSAs) were charged with developing Groundwater Sustainability Plans (GSPs) to avoid undesirable effects of ongoing groundwater depletion. To meet these goals, many GSPs include managed aquifer recharge (MAR) as one of several key tools to improve groundwater sustainability.

Agricultural Managed Aquifer Recharge (AgMAR) is the act of intentionally flooding fallow, dormant, or active cropland when excess surface water is available. AgMAR has the potential to be a cost-effective and high impact form of MAR due to the large acreage of cropland throughout California. As more farmers adopt AgMAR, there is greater urgency to understand the potential water quality risks and benefits associated with recharge. While pesticides and geogenic contaminants such as arsenic pose additional water quality concerns in MAR projects, this paper focuses specifically on water quality considerations for nitrate and salts related to AgMAR activities.

Nitrate contamination of groundwater is expected to worsen into the future. However, a combination of improved nutrient management and carefully implemented AgMAR projects could improve groundwater quality faster than under business as usual. Improvements in nitrogen management practices should be prioritized to reduce current and future nitrogen (N) loading to groundwater. Furthermore, relatively clean (nitrate free) recharge water (e.g. high magnitude flood flows) should be used during AgMAR events in order to dilute incoming and existing nitrate in groundwater. AgMAR programs should prioritize sites that can recharge in longer-duration single-flooding events, such as sandier sites, to capitalize on the dilution effect and reduce biologically mediated mineralization of organic N (the conversion of organic N to nitrate).

AgMAR alone will not lead to substantive improvement in groundwater quality with respect to nitrate without concomitant improvements in current agronomic nitrogen management and sufficient water for dilution. The development of transparent and easy-to-use tools that estimate the amount of residual nitrate at the end of a growing season, the amount of water needed to dilute nitrate under AgMAR, and time of travel to groundwater will help in the successful implementation of recharge projects to avoid negative water quality externalities. Current nitrogen loading maps and locations of drinking water supply wells can be used by GSAs to get a sense of regional nitrogen loading to groundwater and help in planning and prioritizing efforts on sites to target for AgMAR.

Protecting Groundwater Quality While Replenishing Aquifers

February 2, 2023 No Comments

This document represents a first step towards management guidance for on-farm recharge planners and practitioners to maximize benefits to water quality and to manage risks under AgMAR. This document is also intended to be used as a resource for communities so they can more fully participate in the GSA decision-making process.

The intent of this management brief is to build understanding of how drinking water could be affected by AgMAR and identify management considerations that can be used to design AgMAR projects that are mindful of water quality. These considerations are neither prescriptive nor meant to cover the full scope of considerations needed to implement a successful recharge project or program (i.e., analysis of soil and crop suitability, hydrogeology, water rights and availability, and conveyance infrastructure, among other topics).

Protegiendo la Calidad del Agua Subterranea Mientras se Reponen los Acuiferos

February 2, 2023 No Comments

Este documento representa un primer paso hacia la guía de manejo para los administradores y profesionales de la recarga a nivel parcela para maximizar los beneficios para la calidad del agua y manejar los riesgos bajo Ag-MAR. Este documento también está destinado a ser utilizado como un recurso para que las comunidades puedan participar más plenamente en el proceso de toma de decisiones de la GSA.

La intención de este informe de manejo es desarrollar la comprensión de cómo Ag-MAR podría afectar el agua potable e identificar las consideraciones de manejo que se pueden utilizar para diseñar proyectos Ag-MAR que tengan en cuenta la calidad del agua. Estas consideraciones no son prescriptivas ni pretenden cubrir el alcance completo de las consideraciones necesarias para implementar un proyecto o programa de recarga exitosa (es decir, análisis de cultivos adecuados de suelos y cultivos, hidrogeología, derechos y disponibilidad de agua e infraestructura de flujo, entre otros temas).

Soil Agricultural Groundwater Banking Index

January 20, 2023 No Comments

The Soil Agricultural Groundwater Banking Index (SAGBI) is a suitability index for groundwater recharge on agricultural land. The SAGBI is based on five major factors that are critical to successful agricultural groundwater banking: deep percolation, root zone residence time, topography, chemical limitations, and soil surface condition.

Coyote Valley Conservation Areas Master Plan

December 7, 2022 No Comments

ABOUT COYOTE VALLEY
Coyote Valley is a rural and natural area located at the southern edge of San Jose and is one of the last remaining undeveloped valley floors in the region. Approximately seven miles long and two miles wide, it is defined by the Diablo Range to the east and the Santa Cruz Mountains to the west. The valley is remarkable for its role connecting the ecosystems of the Santa Cruz Mountains with the rest of California, as well as its scenic beauty, rich biodiversity, prime farmland, and unique water resources. The Santa Clara Valley Open Space Authority (Authority) and its partners have made protection of Coyote Valley a top priority, and in recent years approximately 1,500 acres of valley-floor land have been permanently protected.

ABOUT THE MASTER PLAN
The Coyote Valley Conservation Areas Master Plan (CVCAMP) will create a roadmap for implementing wildlife linkages, restoring water resources and habitat, supporting climate-smart agriculture, and providing equitable public access on Coyote Valley’s protected lands. The CVCAMP is managed by Authority in close partnership with the Peninsula Open Space Trust (POST) and the City of San Jose and will be created via an integrated, science-based planning process shaped by robust and inclusive stakeholder and community engagement.

COYOTE VALLEY’S WATER RESOURCES
A key focus element of the CVCAMP will be restoration of the historic Laguna Seca wetlands—the largest freshwater marsh in the region—and rehabilitation of a heavily modified creek system in the Fisher Creek floodplain. Restoration of these water resources will entail retirement of constructed channels, levees, and an earthen dam, and restoring natural landscape processes that will help rebuild the landscape’s capacity to buffer surrounding and downstream areas from increasingly unpredictable flood and stormwater events resulting from climate change. Floodplain restoration will also result in increased climate resilience for the region, enhanced habitat for wildlife, and a suite of other co-benefits like flood-managed aquifer recharge and carbon sequestration.

PROJECT TEAM, SCHEDULE, & FUNDING
In late 2021, the Authority hired a team of technical experts led by the firm SWCA Environmental Consulting & Engineering, Inc. to work on the CVCAMP. The Authority anticipates a three-to-five-year integrated planning effort. The CVCAMP will identify early implementation projects to be constructed within the next five to ten years, as well as develop a larger programmatic vision with a 20-to-30-year time horizon. Planning work is funded by the Authority and POST with generous support from partners, including the California Wildlife Conservation Board, and from the County of Santa Clara Parks & Recreation Department.

Flood-MAR Research and Data Development Plan

September 15, 2022 No Comments

This Flood-MAR Research and Data Development Plan (R&DD Plan) presents the work of the Flood-MAR Research Advisory Committee (RAC), a multidisciplinary group of subject matter experts across 13 research themes. The RAC was tasked to identify the research, data, guidance, and tools necessary to support and expand the implementation of Flood-MAR projects. Well-formulated Flood-MAR projects can benefit Californians and the environment through improved water supply reliability, flood-risk reduction, drought preparedness, aquifer replenishment, ecosystem enhancement, subsidence mitigation, water quality improvement, working landscape preservation and stewardship, climate change adaptation, recreation, and aesthetics

Flood-MAR White Paper

September 15, 2022 No Comments

The California Department of Water Resources (DWR) prepared this white paper to explore opportunities to use flood water for managed aquifer recharge (Flood-MAR) because DWR recognizes the need to rehabilitate and modernize water and flood infrastructure in California. Large-scale implementation of Flood-MAR can fundamentally change how flood and groundwater management are integrated by using flood water resulting from, or in anticipation of, rainfall or snowmelt for groundwater recharge on agricultural lands and working landscapes, including but not limited to refuges, floodplains, and flood bypasses.