Policy Considerations for Managing Agricultural Nitrogen to Reduce Groundwater Contamination in California

California Roundtable on Agriculture and the Environment (CRAE) | May 28th, 2013

Recent research, including “The California Nitrogen Assessment”1 and the UC Davis Report for the SWRCB SBX2 1 Report to the Legislature2, has produced an important co

Recent research, including “The California Nitrogen Assessment”1 and the UC Davis Report for the SWRCB SBX2 1 Report to the Legislature2, has produced an important collection of data about how nitrogen compounds move in the environment. Members of the California Roundtable on Agriculture and the Environment (CRAE) share an interest in meaningfully addressing water quality challenges while maintaining a healthy and prosperous agriculture sector. Because of the serious health concerns associated with nitrate in groundwater, CRAE members agree that the immediate goal should be to find cost-effective solutions to cleaning up drinking water supplies or providing safe alternate sources of drinking water to affected communities. We support ongoing efforts, such as the governor’s Drinking Water Task Force, to address this important issue. While CRAE’s ultimate interest is in addressing the full range of water quality challenges related to agriculture—from drinking water to legacy issues, groundwater to surface water, and nitrate to Total Maximum Daily Loads (TMDLs)—and supporting improved nutrient management broadly speaking, the group has chosen to focus specifically on the longer-term challenge of reducing nitrate loading in groundwater from agricultural sources. Recognizing that a range of research and policy processes to address the harmful impacts of excess reactive nitrogen-based compounds in the environment are ongoing, CRAE stakeholders agreed that a focus on preventing further contamination of groundwater from nitrate is an area where CRAE has a unique opportunity to contribute. Furthermore, we anticipate that approaches to reduce nitrate loading that adhere to the considerations below will simultaneously improve other challenges, including air quality, energy use, and climate change. Nitrate contamination is projected to increase in the coming years as legacy contributions work their way through the soil profile. The short-term remediation of groundwater basins is so costly as to be practically impossible. Therefore, CRAE has concentrated on intermediate and longer-term groundwater quality issues by helping to find practical solutions to groundwater quality challenges. Reflecting our membership composition, our focus is on the contribution of agricultural sources of nitrate in particular. CRAE has compiled the following set of key facts on our state of knowledge about nitrogen management and a set of considerations to inform related policy and programs focused on improving water quality.

Projecting groundwater storage changes in California’s Central Valley

Nature Portfolio (Springer Nature) | August 27th, 2018

Accurate and detailed knowledge of California’s groundwater is of paramount importance for statewide water resources planning and management, and to sustain a

Accurate and detailed knowledge of California’s groundwater is of paramount importance for statewide water resources planning and management, and to sustain a multi-billion-dollar agriculture industry during prolonged droughts. In this study, we use water supply and demand information from California’s Department of Water Resources to develop an aggregate groundwater storage model for California’s Central Valley. The model is evaluated against 34 years of historic estimates of changes in groundwater storage derived from the United States Geological Survey’s Central Valley Hydrologic Model (USGS CVHM) and NASA’s Gravity Recovery and Climate Experiment (NASA GRACE) satellites. The calibrated model is then applied to predict future changes in groundwater storage for the years 2015–2050 under various precipitation scenarios from downscaled climate projections. We also discuss and project potential management strategies across different annual supply and demand variables and how they affect changes in groundwater storage. All simulations support the need for collective statewide management intervention to prevent continued depletion of groundwater availability.

Reconciling fish and farms: Methods for managing California rice fields as salmon habitat

PLOS | February 24th, 2021

Rearing habitat for juvenile Chinook Salmon (Oncorhynchus tshawytscha) in California, the southernmost portion of their range, has drastically declined throughout the pa

Rearing habitat for juvenile Chinook Salmon (Oncorhynchus tshawytscha) in California, the southernmost portion of their range, has drastically declined throughout the past century. Recently, through cooperative agreements with diverse stakeholders, winter-flooded agricultural rice fields in California’s Central Valley have emerged as ecologically functioning floodplain rearing habitat for juvenile Chinook Salmon. From 2013 to 2016, we conducted a series of experiments examining methods to enhance habitat benefits for fall-run Chinook Salmon reared on winter-flooded rice fields in the Yolo Bypass, a modified floodplain managed for flood control, agriculture, and wildlife habitat in the Sacramento River Valley of California. Investigations included studying the effect of 1) post-harvest field substrate; 2) depth refugia; 3) duration of field drainage; and 4) duration of rearing occupancy on in-situ diet, growth and survival of juvenile salmon. Post-harvest substrate treatment had only a small effect on the lower trophic food web and an insignificant effect on growth rates or survival of rearing hatchery-origin, fall-run Chinook Salmon. Similarly, depth refugia, created by trenches dug to various depths, also had an insignificant effect on survival. Rapid field drainage yielded significantly higher survival compared to drainage methods drawn out over longer periods. A mortality of approximately one third was observed in the first week after fish were released in the floodplain. This initial mortality event was followed by high, stable survival rates for the remainder of the 6-week duration of floodplain rearing study. Across years, in-field survival ranged 7.4–61.6% and increased over the course of the experiments. Despite coinciding with the most extreme drought in California’s recorded history, which elevated water temperatures and reduced the regional extent of adjacent flooded habitats which concentrated avian predators, the adaptive research framework enabled incremental improvements in design to increase survival. Zooplankton (fish food) in the winter-flooded rice fields were 53-150x more abundant than those sampled concurrently in the adjacent Sacramento River channel. Correspondingly, observed somatic growth rates of juvenile hatchery-sourced fall-run Chinook Salmon stocked in rice fields were two to five times greater than concurrently and previously observed growth rates in the adjacent Sacramento River. The abundance of food resources and exceptionally high growth rates observed.

Reduction of Nitrates in Groundwater – Agricultural Expert Panel Report

California State Water Resources Control Board (SWRCB) | September 9th, 2014

Recommendations to the State Water Resources Control Board pertaining to the Irrigated Lands Regulatory Program The Agricultural Expert Panel (Panel) was convened to a

Recommendations to the State Water Resources Control Board pertaining to the Irrigated Lands Regulatory Program The Agricultural Expert Panel (Panel) was convened to address thirteen questions posed by the State Water Resources Control Board (State Water Board). The questions were primarily technical in nature, and are abbreviated below. 1. How can risk to or vulnerability of groundwater best be determined in the context of a regulatory program such as the Irrigated Lands Regulatory Program (ILRP)? 2. Evaluate and develop recommendations for the current approaches taken to assessing risk to or vulnerability of groundwater. 3. How can risk to or vulnerability of surface water best be determined in the context of a regulatory program such as the ILRP? 4. Evaluate and develop recommendations for the current approaches taken to assessing risk to or vulnerability of surface water. 5. What management practices are expected to be implemented and under what circumstances for the control of nitrogen? 6. What management practices are recommended for consideration by growers when they are selecting practices to put in place for the control of nitrogen? 7. Evaluate and make recommendations regarding the usage of various nitrogen management and accounting practices. 8. Evaluate and make recommendations regarding the most effective methods for ensuring growers have the knowledge required for effectively implementing recommended management practices. 9. What measurements can be used to verify that the implementations of management practices for nitrogen are as effective as possible? 10. Evaluate and make recommendations regarding the usage of various verification measurements of nitrogen control. 11. Evaluate the relative merits, and make recommendations regarding the usage of, surface water measurement systems derived from either receiving water or a discharge monitoring approach to identify problem discharges. 12. Evaluate and make recommendations on how best to integrate the results of the Nitrogen Tracking and Reporting System Task Force with any above recommendation regarding management practices and verification measures. 13. Evaluate and make recommendations on the reporting requirements to report budgeting and recording of nitrogen application on a management block basis versus reporting aggregated numbers on a nitrate loading risk unit level.

Reference Guide to On-Farm Groundwater Recharge on Annual Cropland | Recommendations for Creating Waterbird Habitat Benefits

Nature Conservancy | May 1st, 2019

With the Sustainable Groundwater Management Act (SGMA) requiring basins to balance water budgets and manage groundwater sustainably, there is an opportunity to demonstr

With the Sustainable Groundwater Management Act (SGMA) requiring basins to balance water budgets and manage groundwater sustainably, there is an opportunity to demonstrate groundwater recharge with benefits to birds and people. A multiple-benefit approach brings together water managers, farmers, agencies and conservation groups to stabilize groundwater in a manner that provides greater water reliability for farms and communities while protecting ecosystems, including migratory bird habitat.

Report of the Governor's Task Force on the Acreage Limitation Problem

State of California | January 4th, 1968

Report to the California State Legislature Joint Legislative Budget Committee on Reduction of Agricultural Pollution Runoff into the Sacramento-San Joaquin Delta

California State Water Resources Control Board (SWRCB) | December 1st, 2010

This report has been prepared pursuant to the requirements of the Supplemental Report to the 2008 Budget Act: “On or before March 30, 2009, State Water Resources Con

This report has been prepared pursuant to the requirements of the Supplemental Report to the 2008 Budget Act: “On or before March 30, 2009, State Water Resources Control Board (State Water Board) shall submit a report to the Joint Legislative Budget Committee and to the relevant policy committees that details: (a) the precise actions the State Water Board would have to undertake to obtain a 30 percent reduction to agricultural pollution runoff in to the Sacramento-San Joaquin Delta [Delta] and its tributary watersheds by 2012, (b) the estimated costs of those actions, and (c) which of those actions can be completed administratively and which would require legislation to implement.” The Central Valley Regional Water Quality Control Board, (Central Valley Regional Water Board) staff has determined that replacing irrigation practices that produce return flow is the only method of ensuring a 30 percent reduction in agricultural pollution runoff to the Delta by 2012. The program would be focused within the Delta and San Joaquin River watershed and apply to surface return flow (tailwater). Tailwater can convey contaminants applied to or on the land surface, such as pesticides, sediment, fertilizer, and manure. Tile water (subsurface drainage pumped to surface waters) contains naturally occurring minerals found in ground water, and may contain contaminants leached into the ground water due to application on the land surface. However, tile water is not the focus of this control strategy, since it would take longer to implement the required control technologies. Irrigation return flow is the focus of this effort, since it is more amenable to control (versus storm water runoff) and over 60 percent of the exceedances of water quality objectives we have identified occur during the irrigation season.1 A target of converting 50 percent of the irrigated acres that produce runoff to more efficient irrigation practices that produce no runoff is recommended. A 50 percent conversion target is recommended, since there are other pathways for agricultural pollutants to reach the Delta through surface waters (e.g., pesticide drift, tile water drainage), so a larger percentage reduction in irrigation runoff would be needed to ensure that the overall 30 percent pollution reduction goal is achieved. The estimated cost to the agricultural community to implement the required management practices is $250 million - $450 million in capital cost, assuming half of the one million acres of agricultural land requiring improved irrigation management systems would be targeted to meet the 2012 timeframe. Additional Central Valley Regional Water Board staff resources of up to 10 PY would be required to ensure the required practices are implemented.

Review of Research on the Sacramento-San Joaquin Delta as an Evolving Place

Delta Stewardship Council (Delta Council) | May 11th, 2017

Research on the social and natural processes that sustain the unique values of the Delta as an evolving place is sparse and sporadic. We found seven research projects and

Research on the social and natural processes that sustain the unique values of the Delta as an evolving place is sparse and sporadic. We found seven research projects and no established research programs directly aimed at developing an understanding of the processes supporting the Delta as an evolving place. Far more research occurs on other Delta topics, such as water flows, contaminants and nutrients, and at risk species. Nor did we find evidence that research in these other areas is identifying natural processes that could protect and enhance the values of the changing Delta. We therefore recommend an expanded, sustained commitment to research on the unique cultural, recreational, natural resource, and agricultural values of the Delta as an evolving place. The level of effort could resemble that in other Delta subject areas. Priority should be given to research that supports achieving the coequal goals in a manner that protects and enhances these unique values.

Running Dry: Weathering the Great California Drought

Harvard University | December 1st, 2016

Essays include: "Physical Mechanisms of the California Drought" - Richard Seager "Droughts and the Global Economy: Lessons from California" - Jay R. Lund

Essays include: "Physical Mechanisms of the California Drought" - Richard Seager "Droughts and the Global Economy: Lessons from California" - Jay R. Lund "Addressing Variability: Adaptation and Innovation in California’s Water Systems" - Laila Kasuri "The California Case: Managing Groundwater in Irrigated Agriculture" - Josué Medellín-Azuara "The Hidden Health Consequences of Drought" - Rory Stewart & Erika Eitland "California’s Unconventional Energy-Water Nexus" - Jonathan Buonocore, Don Kriens, Susan Cahalan, Drew Michanowicz, Alexandra Gast, Kate Konschnik "The 2 R’s: What Brazil Can Teach Us About California’s Drought" -  Luis Augusto Bertoni Strengari "Carlsbad Desalination: A Leap in Water Prices, for the Better?" - Aldís Elfarsdóttir

Salinity Effects on Agricultural Irrigation‐related Uses

Central Valley Salinity Alternatives for Long-Term Sustainability (CV-SALTS) | December 1st, 2016

Purpose: Summarize current state of knowledge regarding the effects of elevated EC (TDS) concentrations on crop yields with specific attention to seasonal tolerance

Purpose: Summarize current state of knowledge regarding the effects of elevated EC (TDS) concentrations on crop yields with specific attention to seasonal tolerances. Additional information provided regarding federal, state, international regulations and guidelines and effects of elevated EC on turfgrass, landscape plants and wetland plants.