Addressing Impediments and Incentives for Agricultural Reuse

Water Research Foundation | December 6th, 2023

Water systems across the United States are facing unprecedented levels of stress arising from challenges such as a changing climate, aging infrastructure, and shifting pa

Water systems across the United States are facing unprecedented levels of stress arising from challenges such as a changing climate, aging infrastructure, and shifting patterns of water supply and demand. Agricultural water reuse has the potential to increase the resilience of water and agricultural systems through benefits such as supply diversification, access to an additional water supply, nutrient management, and compliance with water quality permits. However, realization of these benefits and scaling reuse are hindered by broad ranging, but surmountable barriers and tradeoffs. Part 1 of this report (Literature Review) provides a synthesis of the health and agronomic risks of agricultural water reuse in the context of current regulatory frameworks. Part 2 of this report (Guidebook) highlights specific strategies for addressing barriers to agricultural water reuse and includes thirteen profiles of projects and programs advancing agricultural water reuse. This work (WRF 4956) directly builds on the lessons learned in WRF 4775, Agricultural Use of Recycled Water: Impediments and Incentives, (Sheikh et al. 2019) and WRF 4829, Economic and Environmental Benefits of Agricultural Water Reuse (Thebo 2021). While the specific drivers and challenges of agricultural water reuse projects vary widely across contexts, several common themes emerged in this work. The most successful agricultural water reuse projects invariably address multiple objectives and deliver co-benefits to diverse stakeholders. They do this through early, ongoing, and strategic stakeholder engagement and partnerships. State and federal agencies can support advancement of agricultural water reuse through robust capacity building programs and integration of co-benefits into funding programs. Science-based regulatory programs that are aligned with the needs of both water agencies and the agricultural sector can streamline permitting processes while remaining protective of human, agronomic, and environmental health. In combination, the research products developed in WRF 4956 aim to support water managers, regulators, and the agricultural sector in identifying and overcoming barriers to agricultural water reuse across diverse geographic and agricultural contexts in the United States.

Advancing Affordability through Water Efficiency

Pacific Institute | September 19th, 2022

This paper examines the relationship between water conservation and efficiency and affordability. Specifically, it examines the near-term effect of water conservation and

This paper examines the relationship between water conservation and efficiency and affordability. Specifically, it examines the near-term effect of water conservation and efficiency on utility bills, i.e., water, wastewater, and energy bills, for conserving households and the longer term effect on water and wastewater costs for the larger community. Finally, the paper identifies common barriers for low- income and other hard-to-reach customers to participate in conservation and efficiency programs, and proposes strategies to overcome those barriers.

Alleviating water scarcity by optimizing crop mixes

Nature Portfolio (Springer Nature) | November 6th, 2023

An Assessment of Urban Water Demand Forecasts in California

Pacific Institute | August 5th, 2020

In California, urban per capita water demand has declined dramatically over the past several decades, driven in part by greater uptake of water-efficient devices. These r

In California, urban per capita water demand has declined dramatically over the past several decades, driven in part by greater uptake of water-efficient devices. These reductions have important implications for estimating future water demand. However, failure to account for the long-term trend of declining per capita water demand has led to routine overestimation of future water demand. This can lead to unnecessary and costly investment in unneeded infrastructure and new sources of supply, higher costs, and adverse environmental impacts. This report examines the accuracy of long-range water demand forecasts for California’s 10 largest urban water suppliers. It finds that per capita water demand declined for all water suppliers between 2000 and 2015. In most cases, reductions in per capita water demand were so large that total water demand declined during this period. Additionally, all water suppliers overestimated demand, driven largely by inflated estimates of per capita water demand and, to a lesser extent, overestimates of population growth rates. The report offers recommendations on how to improve the accuracy of long-range water demand forecasts.

An evolutionary parsimonious approach to estimate daily reference evapotranspiration

Nature Portfolio (Springer Nature) | March 20th, 2024

An Innovative Scheme to Confront the Trade-Off Between Water Conservation and Heat Alleviation With Environmental Justice for Urban Sustainability: The Case of Phoenix, Arizona

American Geophysical Union (AGU) | February 17th, 2023

Annual Report Clean Water State Revolving Fund and the Water Quality, Supply, and Infrastructure Improvement Act of 2014 State Fiscal Year 2017-2018

California State Water Resources Control Board (SWRCB) | December 30th, 2018

The California State Water Resources Control Board (State Water Board), Division of Financial Assistance (DFA) presents the Clean Water State Revolving Fund (CWSRF) annua

The California State Water Resources Control Board (State Water Board), Division of Financial Assistance (DFA) presents the Clean Water State Revolving Fund (CWSRF) annual report for State Fiscal Year (SFY) 2017-18. The State Water Board provided approximately $707 million in new CWSRF financing to 44 projects in SFY 2017-18, which represent a wide variety of projects eligible under the CWSRF. This report describes how the State Water Board met the objectives identified in the SFY 2017-18 CWSRF Intended Use Plan (IUP). 

Assessing Early Implementation of Urban Water Use Efficiency Requirements

Legislative Analyst's Office (LAO) | January 4th, 2024

Legislation approved in 2018 established a long‑term urban water use efficiency framework to “Make Conservation a California Way of Life.” This framework—which is

Legislation approved in 2018 established a long‑term urban water use efficiency framework to “Make Conservation a California Way of Life.” This framework—which is one component of the state’s overall water management strategy—creates new requirements for about 405 urban retail water suppliers that supply water to nearly 95 percent of state residents. This report responds to a requirement contained in the 2018 legislation for our office to assess implementation of the framework. (Our report is not able to address every aspect requested in the legislation due to framework implementation delays.)

Assessment of California's Water Footprint

Pacific Institute | December 11th, 2012

The Pacific Institute has released the first comprehensive assessment of California’s water footprint, providing an important perspective on the interconnections betwee

The Pacific Institute has released the first comprehensive assessment of California’s water footprint, providing an important perspective on the interconnections between everyday activities and impacts to water resources – both at home and around the world. The new report, California’s Water Footprint, analyzes the state’s water footprint – that is the amount of water required to produce the food we eat, the clothes we wear, the beverages we drink, and the other goods on which we rely. The water footprint of the average Californian is 1,500 gallons per day, slightly less than the average American but considerably more than the average resident in other developed countries or in the rest of the world.

California Simulation of Evapotranspiration of Applied Water and Agricultural Energy Use in California

Journal of Integrative Agriculture (Elsevier) | August 5th, 2013

The California Simulation of Evapotranspiration of Applied Water (Cal-SIMETAW) model is a new tool developed by the California Department of Water Resources and t

The California Simulation of Evapotranspiration of Applied Water (Cal-SIMETAW) model is a new tool developed by the California Department of Water Resources and the University of California, Davis to perform daily soil water balance and determine crop evapotranspiration (ETc), evapotranspiration of applied water (ETaw), and applied water (AW) for use in California water resources planning. ETaw is a seasonal estimate of the water needed to irrigate a crop assuming 100% irrigation efficiency. The model accounts for soils, crop coefficients, rooting depths, seepage, etc. that influence crop water balance. It provides spatial soil and climate information and it uses historical crop and land-use category information to provide seasonal water balance estimates by combinations of detailed analysis unit and county (DAU/County) over California. The result is a large data base of ETc and ETaw that will be used to update information in the new California Water Plan (CWP). The application uses the daily climate data, i.e., maximum (Tx) and minimum (Tn) temperature and precipitation (Pcp), which were derived from monthly USDA-NRCS PRISM data (PRISM Group 2011) and daily US National Climate Data Center (NCDC) climate station data to cover California on a 4 km×4 km change grid spacing. The application uses daily weather data to determine reference evapotranspiration (ETo), using the Hargreaves-Samani (HS) equation (Hargreaves and Samani 1982, 1985). Because the HS equation is based on temperature only, ETo from the HS equation were compared with CIMIS ETo at the same locations using available CIMIS data to determine correction factors to estimate CIMIS ETo from the HS ETo to account for spatial climate differences. Cal-SIMETAW also employs near real-time reference evapotranspiration (ETo) information from Spatial CIMIS, which is a model that combines weather station data and remote sensing to provide a grid of ETo information. A second database containing the available soil water holding capacity and soil depth information for all of California was also developed from the USDA-NRCS SSURGO database. The Cal-SIMETAW program also has the ability to generate daily weather data from monthly mean values for use in studying climate change scenarios and their possible impacts on water demand in the state. The key objective of this project is to improve the accuracy of water use estimates for the California Water Plan (CWP), which provides a comprehensive report on water supply, demand, and management in California. In this paper, we will discuss the model and how it determines ETaw for use in water resources planning.