Irrigation in California

Scientific American | January 4th, 1890

Irrigation in U.S. Agriculture: On-Farm Technologies and Best Management Practices

Congressional Research Service (CRS) | October 17th, 2016

Recent threats to water availability as a result of moderate to exceptional drought in several states have raised questions about agricultural water use and efficiencies

Recent threats to water availability as a result of moderate to exceptional drought in several states have raised questions about agricultural water use and efficiencies across the United States. An understanding of common irrigation technologies and the impacts of best management practices in irrigation may be useful to Congress concerning potential policy responses to this issue. As a major user of water, the agricultural industry’s use of water resources continues to be a focal point of agriculture policy. Additional demands on water supplies, extreme weather events (e.g., prolonged drought), and agricultural market conditions have raised producers’ interest in investing in irrigation systems. Increased pressure on the industry to reduce its water use has also drawn interest in the adoption of irrigation technologies and best management practices (BMPs) as a means of achieving efficiency and potential water savings. The federal government performs several roles in assisting agricultural producers with irrigation practices, including financial assistance, technical assistance, research, and monitoring and reporting. The majority of financial and technical assistance is offered through voluntary conservation programs that target increased irrigation efficiency. In some cases, improvements in irrigation efficiency can increase water consumption because farmers increase the number of irrigated acres or grow more profitable, water-intensive crops. This raises questions about how and where federal funds are allocated, particularly in areas where water shortages are a concern. The use and significance of irrigated agriculture varies widely across the United States. Although policy discussions related to irrigation typically focus on western states—home to roughly 71% of irrigated farms—irrigation is practiced in all 50 states and is growing in the east. Over time, there has been a shift in water resources used for irrigation, with an increasing reliance on groundwater and less on the use of surface water. The type of irrigation system used has also shifted over time—from a gravity, or flood-type of irrigation, to potentially more efficient pressurized sprinkler and drip irrigation systems. Pressure systems account for between 58 to 65% of irrigation systems used in the United States and include applicators such as center pivot, surface drip, slide roll or wheel move, and micro sprinkler. Gravity flow, which includes furrow, and controlled and uncontrolled flooding, accounts for approximately 35 to 42% of irrigation systems in the United States. Irrigation BMPs center around how water is managed on a farm and includes on-farm conveyance, irrigation scheduling, and application methods. Increasingly, precision technologies (e.g., drones, sensor networks, data analytics, etc.) are becoming a common part of many irrigation systems because of their potential to increase efficiencies and reduce costs. The use of irrigation technology and BMPs bring both benefits and costs. The control of water application achieved through irrigation systems can create higher yields and allow the production of higher value crops, while potentially reducing some production costs. The additional cost of installing and maintaining these systems, however, can present a barrier to implementing BMPs. Accounting for variations in the local climate, soil type, water quality, and water availability may also challenge adoption of irrigation technologies and BMPs.

Land Transitions and Dust in the San Joaquin Valley

Public Policy Institute of California (PPIC) | July 24th, 2022

The Sustainable Groundwater Management Act (SGMA) requires groundwater users to bring their basins into balance over the next two decades. In the San Joaquin Valley, this

The Sustainable Groundwater Management Act (SGMA) requires groundwater users to bring their basins into balance over the next two decades. In the San Joaquin Valley, this will mean taking more than 500,000 acres of agricultural land out of intensive irrigated production. Among other issues, this could potentially lead to air quality impacts if the lands become new sources of dust, especially windblown dust, which can have numerous negative short- and long-term health and environmental impacts. In addition, the changing climate may exacerbate risks as warmer temperatures can dry out soils and increase dust emissions. The overall air quality impact of transitioning agricultural land to new uses is nuanced, but proactive management can help to identify high-risk areas and at-risk communities, and direct effort and funding to the most cost-effective interventions.

Land Use and Water Quality on California’s Central Coast: Nutrient Levels in Coastal Waterways

University of California, Santa Cruz (UC Santa Cruz) | July 17th, 2003

Increased focus on addressing non-point source (NPS) pollution throughout the U.S. has raised awareness of agriculture’s impact on water quality. Growers are being a

Increased focus on addressing non-point source (NPS) pollution throughout the U.S. has raised awareness of agriculture’s impact on water quality. Growers are being asked to voluntarily limit the effects of their operations on adjacent waterways through programs such those initiated by county Farm Bureaus. If pollution cannot be voluntarily controlled, growers may face mandatory regulatory actions in the future. Maintaining water quality is an ongoing challenge in the Monterey Bay watershed, where industry, urban development, and farming all affect sensitive waterways. Excess nitrogen and phosphorous, herbicides, insecticides, and sediments that end up in sloughs and wetlands surrounding Monterey Bay have compromised water quality, contaminated shellfish, birds, and other wildlife, and generated unsafe levels of nitrate in drinking water.  Although nutrient contamination is well recognized, to date there have been few efforts to link water quality with land uses such as urban development and farming in the region. To determine the way that land uses affect nitrogen and phosphorous concentrations in central coast waterways, researchers Marc Los Huertos, Lowell Gentry, and Carol Shennan have monitored water flow and sampled water quality in the Pajaro River and in other Pajaro Valley and Elkhorn Slough watershed creeks and agricultural drainages, for the past two water years (October 2000–September 2002). The research takes place through the UC Santa Cruz Center for Agroecology and Sustainable Food Systems (the Center) and is part of a larger U.S. Department of Agriculture grant awarded to Center director Shennan. This water quality monitoring program was developed in cooperation with the Santa Cruz County Farm Bureau, local Resource Conservation Districts, and other groups.  We are particularly interested in the concentrations of two nutrients, nitrogen (nitrate-N) and phosphorus (ortho-P, also known as soluble reactive phosphorus), that are components of non-point source (NPS) pollution originating from urban and agricultural land uses.

Letter in support of the Temporary Urgency Change Petition (TUCP)

California State Water Resources Control Board (SWRCB) | February 19th, 2023

Levee Decisions and Sustainability for the Sacramento-San Joaquin Delta

University of California, Davis (UC Davis) | August 15th, 2010

Managing Agricultural Irrigation Drainage Water: A guide for developing Integrated On-Farm Drainage Management systems

California State Water Resources Control Board (SWRCB) | May 6th, 2004

Chronic problems of salt, selenium, boron and other naturally occurring elements in surface and groundwater supplies plague agricultural regions throughout the Westside o

Chronic problems of salt, selenium, boron and other naturally occurring elements in surface and groundwater supplies plague agricultural regions throughout the Westside of the San Joaquin Valley and the western U.S. Compounding the problem is the build-up of salty subsurface groundwater resulting from dense clay layers and inadequate natural drainage. The Integrated On-Farm Drainage Management (IFDM) system was developed to manage these problems. A state-of-the-art, yet practical irrigation management system, the IFDM provides for drainage water reuse to improve water availability for crop production and to minimize salt and selenium risks to water quality and the environment. IFDM manages irrigation water on salt sensitive, high value crops and reuses drainage water to irrigate salt-tolerant crops, trees and halophyte plants. Salt and selenium are removed from the farming system and can be marketed. This system views the subsurface drainage water containing salts and selenium as resources, rather than considering them as wastes and environmental problems.

Mid-Kaweah Groundwater Sustainability Agency 2022 First Amended Groundwater Sustainability Plan

Mid-Kaweah Groundwater Sustainability Agency (MKGSA) | July 27th, 2022

Due to size, this file has been divided. Part 1, Part 2, Part 3, Part 4, Part 5, Part 6, Part 7, Part 8, Part 9

Due to size, this file has been divided. Part 1, Part 2, Part 3, Part 4, Part 5, Part 6, Part 7, Part 8, Part 9

Minimizing the Impact of Cannabis Cultivation on California Lands and Waterways

California State Water Resources Control Board (SWRCB) | February 17th, 2017

Following recent changes in state law and voter-approved initiatives, California’s commercial cultivation of cannabis for recreational and medical use is expected to gr

Following recent changes in state law and voter-approved initiatives, California’s commercial cultivation of cannabis for recreational and medical use is expected to grow significantly. The State Water Resources Control Board has adopted a state cannabis policy to set up strict environmental standards, and a permitting system to protect local surface water from dewatering, protect water habitat and prevent pollution in the state’s rivers and streams. Left unregulated, cannabis cultivation can pose serious threats to water quality and the environment. Cannabis cultivation impacts include the release of fertilizers, pesticides and other supplements that degrade water quality and threaten wildlife. Excessive water diversions can injure fish or even dewater smaller streams. The physical alteration of the land can harm stream habitat and wildlife by the sediment and debris that is deposited in waterways by unregulated cultivation. Overview: The State Water Board’s “Cannabis Cultivation Policy, Principles and Guidelines for Cannabis Cultivation” (Policy) will be implemented through a water quality permit and a water right. The water quality permit is referred to as a Statewide General Order for Cannabis Cultivation Activities (Cannabis General Order). The water right is referred to as a Cannabis Small Irrigation Use Registration. Tiered Approach: The Cannabis General Order consists of a tiered permit structure based on threat to water quality. Tier 1 Cannabis Cultivators have a disturbed area greater than 2,000 square feet and less than 1 acre (43,560 square feet). Tier 2 Cannabis Cultivators have a disturbed area equal to or greater than 1 acre.

Modeling the dynamic penetration depth of post-1950s water in unconfined aquifers using environmental tracers: Central Valley, California

Journal of Hydrology (Elsevier) | December 5th, 2022

The penetration depth of post-1950s recharge (D-1950) in aquifers is a marker that is frequently used to identify groundwater that is susceptible to anthropogenic contami

The penetration depth of post-1950s recharge (D-1950) in aquifers is a marker that is frequently used to identify groundwater that is susceptible to anthropogenic contamination. Here, we compute D-1950 values at wells, interpolate them in space, and project them across time to map the moving front of modern recharge in four dimensions in the Central Valley aquifer system, California, USA. Tracers of groundwater age (tritium, carbon-14, noble gases, sulfur hexafluoride, and chlorofluorocarbons) were collected at 650 wells spatially distributed throughout the Central Valley and were fit to a lumped-parameter model that assumes a logarithmic age-depth profile in the aquifer. For samples where tritium was present (>0.3 tritium units), the model was used to predict D-1950 at wells screened above or across the modern-premodern interface (n = 484). Wells with samples where tritium was absent (≤0.3 tritium units) were used to define the depth beyond which groundwater is completely premodern (n = 166). Predicted D-1950 values were below the depth of screen bottoms for wells where groundwater is completely modern, and above the depth of screen tops for wells where groundwater is completely premodern. The interpolated surface of D-1950 is dynamic, less prone to extreme values, and produces maps with lower interpolation errors due to a higher spatial density of wells than maps based on the depth of premodern groundwater. Between 2005 and 2025, D-1950 is expected to deepen by 11 and 12 m in the northern and southern parts of the Central Valley, respectively. Areas where D-1950 increases rapidly are likely to see increases in nitrate and other anthropogenic contaminants associated with the downward moving front of modern water.