Specific Objectives of the Project:
The overall objective of this research project is to analytically and empirically address nonpoint salinity pollution from agricultural activities by simulating a market framework for pollution permits and other regional cooperative arrangements between agricultural growers (polluters) and regulatory agencies aimed at controlling pollution to a water body (e.g., river, aquifer). That framework will then be applied to the case of salinity management in the San Joaquin Valley, California.

Specific objectives include:

1. Develop an analytical framework for quantifying, comparing and prioritizing policy interventions aimed at regulating nonpoint salinity pollution from irrigated agriculture.
2. Apply the analytical framework, developed under objective (2) to the case of the San Joaquin River Basin, California where agricultural producers are constrained by regulations that limit their ability to farm, leading occasionally to non-compliance with these regulations.
2.1 Compare several regional settings: including a status quo without regulation; a cap and trade of salinity pollution; and several cooperative arrangements among agricultural producers and between the agricultural producers and the regulating agency.
2.2 Introducing information and data sharing equipment to allow calculation of the value of information to the polluters and to the regulatory agency.

Summary of Results:
This project presents an alternative approach to salt regulation and control that follows first attempts to implement the 2002 TMDL, when it was realized that TMDL policy objectives could not be achieved without potential annual costs to stakeholders in the millions of dollars annually, using typical penalty schedules for daily exceedance of a 30-day running average EC objective at a single downstream compliance site. These costs would have potentially risen with the inclusion of two additional upstream compliance monitoring sites adopted to protect agricultural riparian diverters from high salt concentrations in irrigation applied water.

The novel concept of “Real-Time Water Quality management” relies on a continually updated forecasting model to provide daily estimates of salt load assimilative capacity in the San Joaquin River and assessments of compliance with salinity concentration objectives at three monitoring sites on the river, based on the 30-day running average EC. A water quality forecasting model WARMF was developed as part of this alternative regulatory schema, which served both as a compliance forecasting tool and the means by which salt load allocations and salt exports from each of the seven contributing subareas could be estimated and compared. The trading of salt loads between subareas is now feasible as both the regulatory salt load allocation and actual salt load discharge to the river can be quantified.

The results of the study have shown that the policy combination of well-crafted river salinity objectives by the regulator and the application of an easy-to use and maintain decision support tool by stakeholders have succeeded in minimizing water quality (salinity) exceedances over a 20-year study period. The WARMF model improvements, and consequent increase in stakeholder and agency confidence in this decision support tool, suggest its potential application in other river basins facing similar challenges. Our framework allows farmers and regulators to jointly understand and evaluate the meaning of various regulatory policy interventions on the emission of salinity and on the cost to be incurred by farmers at various locations along the river. The results support the development of close collaboration between farmers and regulators in the application of non-point source pollution policy. The results also suggest significant benefit from better cooperation and coordination among and between farmers and other dischargers of salt load who rely on the river for drainage disposal and who are already organized into sensible subareas for salt management. This can provide a cost-effective pathway for agricultural sustainability.

Specific Objectives of the Project:

1. Catalogue the various locations of LS in California based on the severity of the land subsidence issues;
2. Develop an analytical framework to evaluate the tradeoff between benefits from pumping groundwater for consumption in urban and irrigation activities and the social cost of doing so (including energy for pumping from deeper level, water quality degradation from intrusion of low-quality water, and damages from LS to infrastructure and from groundwater storage loss);
3. Derive optimal rates of pumping of groundwater for combinations of aquifer geological formations and value of water in economic activities;
4. Apply the analytical framework to several locations in California known to be affected by LS.

Project Report/Summary of Results:

Land subsidence (LS) is the settlement of the land surface triggered by human-induced and natural-driven processes, such as oxidation of organic soils, sub-surface water mining, or fluids extraction (oil, gas and groundwater). Land subsidence is a global problem, mostly studied and recognized, to different extents, in association with aquifer over-exploitation. LS occurrence around the world is most prominent in those aquifers composed of loose unconsolidated materials (e.g. sands, clays, silts, etc.) that are over pumped.

It is assessed that LS inflicts significant damages on local communities and on the environment.  As such, identifying the types of damages and quantifying them both in terms of the various physical impacts and their economic values, short- and long-term, would be an essential first step for preparing policies to address the problem.

Most studies on LS are indicative in the sense that they identify the driving process and measure the land subsidence amount and extent in a specific locality. Few are the works that assess the impacts of LS in terms of social, environmental and economic consequences.

In this project we developed two research directions (1) development of a regional model to explain the economics of optimal GW pumping in the presence of LS and (2) development of a quantitative method to assess the extent of LS and apply it to various aquifers.       

Our findings suggest that optimal GW pumping regimes in the presence of LS should be more conservative than when LS is minimal or not absence. Damages to infrastructure and loss of storage capacity inflict major social costs that affect the optimal pumping regime and should be part of a regional policy to sustain the regional resources.  The model was applied in three locations: Po Basin, Italy; Murcia, Spain; Chino Basin, California and demonstrated the value of preventive and responsive policies.

Findings from the second research direction, while still in progress, quantified, based on data from 119 locations globally, relationship between Extent of Land Subsidence and explanatory variables to suggest the impact of climatic, institutional, geological, and policy interventions on the extent of the impact of land subsidence damages measured by a vector of 10 damage aspects.

Specific Objectives of the Project
The overall objective of this proposed research is to examine the feasibility of a long-term arrangement between the City of Escondido and the avocado growers in the region, regarding the sale of treated wastewater by the city to the growers. Such agreement would maximize long-term benefits for the region. The stability of such agreement will be investigated empirically, accounting for costs and benefits of both the city and the farming sector, from this agreement. Necessary constraints will be imposed to ensure proper considerations of the impacts on the environment resulting from use of treated wastewater for irrigation.
Specific objectives include:
(2) Apply a regional model that was developed in a recent research project. The model includes optimization of benefits to irrigated agriculture (the consumer of the wastewater) and to a city (the source of the wastewater), subject to regulation of externalities from use of treated wastewater in the form of GW pollution. The model will be calibrated to the region of Escondido in San Diego County, California, using empirical data on treatment cost functions, agricultural production functions and aquifer water pollution, which was collected in the Escondido site during a controlled field experiment in the past 6 years.
(2.1) The empirical model will allow avocado growers in the region to plan their production for the future, with uncertain freshwater availability and unknown quality.
(2.2) The Empirical model will allow the City of Escondido to plan its future treatment facility expansion with population growth and likely revised state wastewater disposal regulations.
(3) Extend the empirical model to several additional regions with similar conditions along the coast of California, where wastewater is being treated and disposed of to the ocean.

Project Report/Summary of Results
Wastewater has become a valuable resource in many regions of the world that face increased level of freshwater scarcity. Reuse of treated wastewater is associated with high economic benefit, but it can also lead to pollution of the environment and water bodies. As such, explicit conditions must be defined to determine the optimality of wastewater reuse for society. In this project, we developed a regional multi-sectoral model of water quantity-quality interaction among the urban, agricultural, and environmental sectors.

Interested in the feasibility of reuse, rather than the stability of the regional arrangements, we apply a social planner’s approach to the regional problem. We formally derived sufficient conditions that support the superiority of infrastructure development and conveyance of treated wastewater for irrigation, when measured against other common disposal alternatives (such as ocean disposal, or disposal to nearby dry riverbed). Using a numerical illustrative example, which relies on data and results from existing literature, we were able to replicate our theoretical findings, as well as to examine their robustness, when several supporting assumptions are relaxed.

We then turned to the region of Escondido in Southern California, where such issues are the forefront of discussions between the city of Escondido and a group of avocado farmers. We collected data from a group of representative growers that are part of the IGAP farmer association to estimate the cost of production of avocado in this region. We obtained soil and climate parameters, as well as groundwater aquifer characteristics in the region. Based on the soil data, climate data, and prices of inputs and the output, we were able to calibrate a production function for the avocado crop in the Escondido region.

Using data and information on wastewater treatment cost from the literature and from the website of the Escondido City Wastewater Treatment Facility we estimated a treatment cost function for Escondido. This function is included in our regional model for the purpose of identifying the cost of unit of treated wastewater under various scenarios that will be part of the analysis we will conduct.

A final component in our analysis is the prediction of population in the city of Escondido in the future, which will affect the amount and cost of treatment of wastewater. We use population estimates for various future years and include it in the model.

We completed the process of (1) calibrating our model to observed parameters such as water availability, avocado prices, cost of wastewater), (2) defining institutional arrangements for a possible agreement between the city of Escondido and the avocado growers for different constraints imposed for protecting the aquifer water quality and quantity.

Specific Objectives of the Project

(1) Estimate, using existing data at individual farm level, the impact of UC Cooperative
Extension efforts on the use of efficient irrigation water across the 58 counties of the state of
California;
(2) Provide an assessment of the relative efficacy of various extension intervention efforts and
investments needed for the different counties to ensure efficient water usage;
(3) Develop a framework to extend the estimation of the impact of Extension services on
irrigation efficiency across the western states of Arizona, California, Colorado, Montana,
Nebraska, Idaho, Oregon, Utah and Washington. (The framework developed under this
proposed Giannini project will be applied, with future funding under a different project to be
sought.)

Summary of Results

University of California Cooperative Extension (UCCE) is responsible for disseminating
irrigation information with the aim of enhancing productivity, using irrigation efficient
technology and water management practices. we estimated the impact of UCCE as a source of
irrigation information and knowhow, on irrigation efficient production and water use for
California’s farmers. The analysis in the paper uses Farm and Ranch Irrigation Survey (FRIS) for
the years 2003 and 2008. Empirical results indicate positive impacts of UCCE on irrigation
efficient production, and water use per irrigated acre. The latter result suggests the phenomenon
of rise in water use due to increased acreage and production, resulting from the use of irrigation
efficient technology and management techniques. UCCE as a source of irrigation information
has a significant impact of $3,035 on farm level irrigation efficient production, and also a 1.17
acre-feet/irrigated acre rise in water use, suggesting selection of a more profitable cropping
pattern. However through the use of the water-saving irrigation systems, farmers do increase the
average value of output per irrigated acre, and incur a net profit, with the increased irrigation
water use. Policy implications based on better understanding of underlying hydrological systems,
can improve water savings. Policy prescriptions also include collaboration of UCCE and other
irrigation information sources, to act as substitutes in the dissemination of irrigation information.

Specific Objectives of the Project
(1) Estimate impact of climate change induced water scarcity on agriculture in southern/desert regions of California;
(2) Model (in a normative framework) possible adaptation responses of agricultural growers across various farm types to water scarcity scenarios predicted to affect the region, and estimate the economic value of such adaptation practices;
(3) Infer the normative results by positively observing decisions of agricultural growers in a subset of the regions.

Project Report/Summary of Results
A preliminary review of the literature was conducted and a review paper was written and submitted to a technical journal; A Ricardian model to allow estimation of impact of climate change on agriculture in Imperial, San Diego, and Riverside counties was developed; Data files from the agricultural commissioner reports were identified for all individual farms in these counties; A questionnaire was developed and being cleared by HRB for phone interview with growers (300, 400, 400 in Imperial, San Diego, and Riverside Counties).
(1) A choice model at the county level was developed; a set of adaptation technologies and practices was identified as bundles of technologies and practices for each county; Using the same data sources as in (1), the data collection is about to culminate in July;
(2) The comparison between the Ricardian model with County fixed effects and the choice model will be conducted once preliminary results are available.

Specific Objectives of the Project

1. Understanding the socio-economic and physical determinants of adoption of technologies and management practices by California Avocado growers.
2. Estimating economic impact of adoption of technologies and management practices on the ability of avocado growers to withstand drought and water quality deterioration.

Summary of Results

Avocado growers use a variety of management practices for crop irrigation and control of soil salinity. When faced with changes in water availability, reliability, and quality, growers must consider not only the effects of these changes on yields, but also the economic implications of their decisions. As new information becomes available on best irrigation practices that conserve water while avoiding salinization, growers must access this information and apply it to their own situation. Avocado is an important crop in the economy of California, which is sensitive to water availability and quality. This study determines how growers make decisions about water management and irrigation technology implemented at their avocado orchards. This study considers how farm traits, socio-economic and regional factors affects how growers adopt strategies and technologies in response to water quantity and quality changes. The results of this study are based on primary information collected from avocado growers in California. The final results will determine which irrigation management strategies are most cost-effective for responding to drought or a shift to low quality groundwater resources, and what are the behavioral aspects of grower decisions with respect to water management and adoption of new technologies. Ultimately, these research findings can both be applied to avocado production globally and extended to other crops that require precision water management.

The objectives of this research were to evaluate the impact of a water conservation program being promoted by many of the water districts in southern California—the high efficiency sprinkler nozzle program—on water use. In particular, we intended to investigate the impact of these sprinkler heads on water use at the household level and the subsequent potential impact at the district level. Furthermore, we attempted to estimate an adoption model that identified factors which influence a household's decision to adopt the technology.

In this program, households can receive vouchers for up to 25 free high efficiency sprinkler nozzle heads. The data consists of monthly water use and household characteristics over ten years on approximately 120,000 residential meters. Our analysis consists of two approaches to evaluating these potential effects. First, we compared different subpopulations average use before and after adoption; second, we estimate a discrete continuous choice (DCC) model. Preliminary results suggest that residential customers who redeemed vouchers for 25 high efficiency sprinkler nozzles typically experienced a subsequent reduction in overall water use of around 1.2%. As a fraction of total outdoor water use, the reduction is around 2.7%. This is markedly lower than the technically achievable reduction of 30% that has been estimated by the manufacturer.

In terms of what factors seem to influence adoption, we find that adoption rates were positively related to house value, income levels, average water prices, ET, household size, and landscape area (although nonlinearly); adoption rates were negatively related to distance to the nearest nozzle head distributor (which suggests travel and time costs are important factors influencing whether households redeem their vouchers). Adoption rates for those in the top, middle, and bottom terciles of water use were approximately 2.3%, 2.0%, and 0.78%. Ongoing research is currently focusing on gathering more complete information on those households that redeemed the vouchers in terms of the number of nozzles they actually installed and the degree to which they were installed correctly.