Report Proposal Status:
Original 2 pager First Update: 00/00/00 --changes marked in red print
Second Update: 00/00/00 --changes marked in green print
Principal Aquifer:
Aquifer Name(s): BARA - Basin and Range / California Aquifers; Rio Grande, Colorado River and Great Basins (MRB 6); California River Basins (MRB 8)
Lead Contact: Sue Thiros
Proposed Report Title:
Effects of agriculture and urbanization on shallow ground-water quality in the arid to semiarid western United States
Scope:
Hydrologic and water-quality data (VOCs, pesticides, nitrate, tritium, stable isotopes, major ions) from NAWQA land-use study (LUS) wells
Study Units: NVBR, GRSL, CAZB, SANJ, SACR, & SOCA (study could possibly be expanded to include the Rio Grande Alluvial System)
Time Period: 1991-2003
Land Use(s): Agricultural and urban land uses
Inter-Regional Principal Aquifer Proposal? Yes/No: Explain: Yes
Constituents:
Expected Authors:
Lead: Rosen
Contributing: Thiros, Schaefer, and other ground-water personnel from this Principal Aquifer Team.
Objectives:
Data Interpretation Approach and Feasibility:
Number of Sites/Components (e.g., nutrients, pesticides): Monitoring wells sampled as part of the 10 NAWQA land use studies done in the Basin and Range, California Coastal, and Central Valley Principal Aquifers area. Components include VOCs, pesticides, nutrients, tritium and/or CFCs, stable isotopes, specific conductance, and major ions.
Methods:
Compare shallow ground-water quality under different land uses using non-parametric statistical tests. Land uses mapped within a 500-meter buffer around monitoring wells could be used in the comparison. Categorical variables may include confined/unconfined aquifers, land use, population density, crop acreage, crop type, precipitation, irrigation/public-supply water usage, and pesticide use. Correlate water-quality data with depth to water, population density , screen/well depth, and chemical usage. Use multivariant statistical methods to determine potential trends between study data sets along a gradient in land use, recharge, climate, population, hydrogeology, etc.
Stage project efforts and review 3 to 4 months into the study. Do some exploratory data analysis on part of the data set, over a spectrum of conditions, to see if there is enough data to do what is proposed and if the results are satisfactory. Share project plans with other Principal Aquifer Report teams with similar reports. They will serve as technical contacts and reviewers.
Data Availability and Processing:
NAWQA data, such as chemical concentrations, are readily available. Acquisition and processing of ancillary data sets will take more time and will require coordination with National Synthesis Team efforts. Other useful sources of data and methods of analysis will need to be identified.
Staff Availability: Yes
Complexity: Low to medium. All of the study units that are part of this Principal Aquifer Team have done at least one land-use study. This study would be a synthesis and analysis of these data sets.
Risks/Contingencies: Low risk level due to availability of most of the data in the NAWQA data warehouse.
Other Program Contacts: Pesticides and Nutrients National Synthesis Teams, National Ground Water Trends Planning Team, other Principal Aquifer Teams, Transport of Anthropogenic and Natural Contaminants Topical Team, Agricultural Chemicals Topical Team
Expected Outcome:
The occurrence of anthropogenic compounds in shallow ground water is nearly ubiquitous in the west, but the types of compounds are hypothesized to change with land use, climate, depth of screened interval/well/water, recharge sources, and vertically verses horizontally dominated flow conditions.
Why is this topic important to report on?
The USEPA and States have mandated responsibilities for assessing ground-water quality and implementing ground-water protection. The NAWQA program, to fulfill one of its primary goals, is designed to evaluate trends in water quality and to assess the potential effects of changing land use on water quality. This study would use a larger data set to determine the relation between land use and shallow water quality in a rapidly urbanizing region of the country. Study findings could assist in understanding the susceptibility of shallow ground water, and possibly underlying water-supply aquifers, to land-use effects in unsampled areas within the region.
Why does this topic need to be addressed now?
Expansion of urban areas into agricultural areas is ongoing in the arid to semiarid western United States resulting in an increased need for drinking-water supply and changes in water-management practices. Shallow ground-water quality often provides an indication of land-use effects that can reach deeper water supplies. As the demand for drinking water increases, the shallow aquifers may become viable sources of drinking water. An understanding of the effects of agricultural and urban land uses and their associated water-management practice on ground-water quality (determined from Cycle I data) is needed relatively quickly to be pertinent to recent conditions.
Why is it appropriate for this topic to be addressed by the USGS? NAWQA? This Regional Team?
The USGS through the NAWQA program and other national and district programs has the resources to address this topic. NAWQA and associated studies provide consistent data sets and methodologies, as well as the spatial and temporal scope to provide a broad picture of land-use effects on ground-water quality. We have a unique database that can track changes in anthropogenic compounds (pesticides and VOCs) that other agencies lack. The lead authors for this proposed report have had experience in their respective study units interpreting the effects of land use on ground-water quality.
Who cares and why?
Regulators such as the USEPA and State and Local agencies can use the results of this study to better understand relationships between land uses and shallow ground-water quality and, therefore, be able to make better water-management decisions based on these interactions, rather than looking at them in isolation. Water suppliers should be interested in this report because of the connection between the shallow ground water and deeper aquifers that are used for public supply in many areas of the western United States. Thad Erickson with the Cache County Water Policy Advisory Board in northern Utah recognized the application of results from a NAWQA land-use study done in Salt Lake Valley to his rapidly urbanizing area. He said, “Our aquifer classification studies have given a measure of comfort that our principal aquifer is of very high quality. This comfort should surely be tempered with the findings from Salt Lake Valley.” A regional analysis of land-use studies would provide his and other growing urban areas with more information that can be used to make land-management decisions.
In addition, managers of surface-water systems will be interested in the quality of shallow ground water because it often interacts with surface-water bodies. The Jordan Valley Water Conservancy District is a major water supplier to the Salt Lake Valley in Utah and is in the process of accessing shallow ground water for public supply to supplement water from wells completed in the deeper aquifer and from various surface sources. This will require a major investment in water-treatment facilities. As the need for water to supply urban areas increases, the shallow aquifers may become sources of public supply in other parts of the arid west, if water-quality issues can be dealt with.
The general public would be receptive to information on the effects of their activities on ground-water quality based on the acceptance of hazardous material disposal programs in many urban areas. Most are concerned about the quality of water that they drink and interact with.
Selected References:
Budget:
FY2004: Primarily data analysis and interpretation
FY2005: Primarily data interpretation and report writing
FY2006: Primarily report review, processing, and publicationSalary rates in FY05 and FY06 are 1.05 the previous year’s rate to account for inflation.