NU Water-Related Research in Rock County

The list below shows water-related research being conducted within your district or that affects your district. They are sorted by water topic, then by primary contact's last name.

Displaying 12 records found for Rock County


Topic Extension
Project's Primary Contact Information
Name Kranz, Bill
Unit Northeast Research and Extension Center
Email wkranz1@unl.edu
Phone 402-475-3857
Web Page
Project Information
Title Northeast Research and Extension Center - Haskell Agricultural Laboratory
Other(s) Charles Shapiro, Northeast Research and Extension Center, cshapiro1@unl.edu; Dave Shelton, Northeast Research and Extension Center, dshelton2@unl.edu; Sue Lackey, Conservation and Survey, slackey1@unl.edu; Terry Mader, Haskell Ag. Lab, tmader1@unl.edu 
Description

The role of the faculty and staff in this unit is to prevent or solve problems using research based information. Faculty and staff subscribe to the notion that their programs should be high quality, ecologically sound, economically viable, socially responsible and scientifically appropriate. Learning experiences can be customized to meet the needs of a wide range of business, commodity, or governmental organizations based upon the many subject matter disciplines represented. As part of the University of Nebraska, the Northeast Center faculty and staff consider themselves to be the front door to the University in northeast Nebraska. Through well targeted training backgrounds and continuous updating via the internet and other telecommunications technologies, faculty and staff have the most current information available to help their clientele.

The Haskell Ag. Lab is a University of Nebraska research farm located 1.5 miles east of the Dixon County Fairgrounds in Concord. This 320 acre farm was donated to the University of Nebraska by the C.D. Haskell family of Laurel in 1956. A number of demonstrations and projects are going on at the Haskell Ag. Lab, including a riparian buffer strip demonstration and a study to evaluate the effect of irrigation on soybean aphid population dynamics. Other studies focus on:

Subsurface Drip Irrigation: In the spring of 2007 a new subsurface drip irrigation system was installed on a 4 acre portion of the farm with sandy loam soils. The initial objective of the research is to collect field data to document crop water use rates for new corn varieties. Specifically, the work will concentrate on varieties that have different drought resistance ratings to improve the accuracy of the information provided to producers via the High Plains Regional Climate Center. In 2007, two varieties were planted and five irrigation treatments were imposed ranging from dryland to full irrigation. The data will also be used to develop improved local crop production functions for use in the Water Optimizer spreadsheet.

Hormones in Livestock Waste: This project will evaluate the fate of both naturally occurring and synthetic hormones that are associated with solid waste harvested from beef cattle feeding facilities. The research involves: 1) tracking the fate of hormonal compounds from the feedlot into surface run-off that would make its way into a liquid storage lagoon; 2) establishing stockpiled and composted sources of the solid manure removed from the feedlot; and 3) applying stockpiled and composted manure to cropland areas under different tillage systems and native grasses. Once the manure is applied the runoff potential will be evaluated using a rainfall simulator. Research will then focus on whether plants that could be a source of food for wildlife and/or domestic animals take up the hormones. (More information about this project is available; see projects listed under Dan Snow.)

Project Support Varies according to program and project - for more information see http://nerec.unl.edu/ Hormone Project funded by the U.S. Environmental Protection Agency
Project Website http://nerec.unl.edu/
Report
Current Status Continuous
Topic Groundwater
Project's Primary Contact Information
Name Swinehart, James B.
Unit School of Natural Resources
Email jswinehart1@unl.edu
Phone 402-472-7529
Web Page http://snr.unl.edu/aboutus/who/people/faculty-member.asp?pid=487
Project Information
Title Geology and Groundwater Supplies of Box Butte County, Nebraska
Other(s) Vernon L. Souders (project lead, retired); Frank A. Smith (retired), fsmith1@unl.edu 
Description

This report describes the relationship between the geology and the groundwater supplies in Box Butte County. It also evaluates the aquifers with respect to waterbearing characteristics and groundwater in storage. It further describes recharge to and discharge from the aquifers, outlines the movement of groundwater in the county, and summarizes the changes in groundwater storage that have occurred since the advent of irrigation in the county. Brief descriptions of the topography and drainage are included. An evaluation of climatic data for Box Butte County and the Nebraska Panhandle is incorporated into this report and several observations are made about climate in relation to groundwater and the irrigation requirements of crops. Brief mention is made of the soils and agricultural activity in the county.

The report estimates that to date (1975-1976) the amount of groundwater in storage has decreased 2-3% since 1938 and perhaps 1/2 of this decrease has occurred since 1964. The most serious water level declines were immediately north of Alliance in an area where the groundwater resource is large. This area had the highest concentration of irrigation wells and is also the oldest irrigated part of the county.

The report explicitly does not answer the question, "How long will the water supply last?" Rather the authors make the point that economic considerations and social attitudes are just as important as the characteristics of local groundwater supplies in answering that question.

Project Support Upper Niobrara White Natural Resources District, U.S. Geological Survey
Project Website
Report WSP-47.pdf
Current Status Test Holes Drilled Fall 1975-Spring 1976, Report Published 1980. An electronic copy of the report is available above; A hard copy is available via Nebraska Maps and More
Topic Hydrology
Project's Primary Contact Information
Name Ayers, Jerry
Unit School of Natural Resources
Email jayers1@unl.edu
Phone 402-472-0996
Web Page http://snr.unl.edu/aboutus/who/people/faculty-member.asp?pid=5
Project Information
Title Box Butte County / Niobrara River Numerical Groundwater Flow Model Studies
Description

The main objective of these studies was to determine the effect, if any, of large-scale regional pumping on the base flow of the Niobrara River. One study involved the construction and implementation of a groundwater-flow model for Box Butte County and the surrounding region to simulate hydrogeologic and hydraulic conditions, including groundwater extraction by large-capacity wells. The other study focused on the upper reaches of the Niobrara River to obtain estimates of stream-bed hydraulic conductivity (i.e., the ease with which water can move through pore spaces or fractures in the stream-bed) to be used as input to the modeling effort.

The groundwater-flow model was calibrated to predevelopment by primarily adjusting recharge flux through a trial-and-error process until a reasonable fit was obtained to the observed water table configuration of 1938. Once calibrated to predevelopment heads, transient simulations (i.e., simulations taking into account real-life conditions, thus modeling potential real-life changes in the basin), were run to model the change in heads due to pumping for the time period between 1938 and 2005. Results from these simulations were compared with observed heads for available years. After satisfactory results were obtained from the transient simulations, two additional scenarios were tested. These were simulations where all wells were turned off and where only those wells in Box Butte County and its proximity were active. The computer program ZONEBUDGET, which computes the water budget for user-defined zones, was run coincident with all simulations. Both head and water budget computation results were then used to determine the effect of pumping on the base flow the Niobrara River.

Based on model results, reductions in the base flow of the Niobrara River is due primarily to localized pumping effects, rather than from groundwater extraction on a regional scale. A comparison of simulated outflow values for selected reaches of the Niobrara River indicates that 1) flow characteristics in the uppermost part of the basin did not change greatly over the period of pumping indicating that base flow is not significantly reduced by large-scale pumping, 2) significant changes in base flow appear to have occurred after about 1960 in the middle and lower reaches, 3) the maximum change in flow for the middle reach due to all wells pumping is 19.6% and only 4.4% for Box Butte wells, with both maximum reductions occurring at the end of the 2005 pumping season, 4) the maximum change in flow for the lower reach is about 24.4% for all wells and only 2.5% for Box Butte wells, again, both occur at the end of the 2005 pumping season. Overall, the Niobrara River appears to be a gaining stream along most of its flow path, with the exception of the uppermost part of the basin.

The conclusion is that the affects of large-scale regional pumping appears to not impact base flow in the Niobrara River to any significant degree. Rather, localized pumping, especially where irrigation wells are situated near the river, reduces base flow on the order of 20% to 25%. For the most part, the Niobrara River valley is somewhat isolated from the extensive pumping taking place in Box Butte County. The upper reach is sufficiently distant from the pumping center that the cone of depression has little effect on the water table. Much of the middle reach transects units of the White River group that are considered to be nearly impermeable, and thus, provide a hydrogeologic barrier, preventing the northward expansion of the cone of depression. Pumping along the lower reach of the Niobrara River has a much greater influence on base flow reduction simply due to the proximity of the extraction wells to the river.

Project Support Nebraska Department of Natural Resources
Project Website http://www.dnr.state.ne.us/Publications_Studies/Box-Butte_ModelProjectCompletionReport.pdf
Report
Current Status Completed
Topic Hydrology
Project's Primary Contact Information
Name Chen, Xun-Hong
Unit School of Natural Resources
Email xchen2@unl.edu
Phone 402-472-0772
Web Page http://snr.unl.edu/aboutus/who/people/faculty-member.asp?pid=19
Project Information
Title Hydrologic Connections in the Elkhorn River Basin
Other(s) Sue Lackey, Conservation and Survey, slackey1@unl.edu 
Description This project involves investigating the hydrologic connections between streams and the adjacent aquifer systems in the Elkhorn River Basin. Researchers have used a Geoprobe direct-push technique, in-situ permeameter tests, and a thermal camera to collect data in this basin. Research has been conducted in Taylor Creek (west of the City of Madison), in Maple Creek, and two sites in the Elkhorn River near Norfolk and Meadow Grove. Ultimately this data will be used for integrated management of surface and groundwater resources.
Project Support Nebraska Department of Natural Resources, Upper Elkhorn Natural Resources District, Lower Elkhorn Natural Resources District
Project Website
Report
Current Status Continuous
Pic 1 Project Image
Pic Caption 1 This image shows our work in the Elkhorn River near Meadow Grove and in Taylor Creek. 
Pic 2 Project Image 2
Pic Caption 2 Direct-push techniques used by UNL researchers for study of stream-aquifer connections in Madison County, Nebraska. 
Topic Hydrology
Project's Primary Contact Information
Name Lenters, John
Unit School of Natural Resources
Email jlenters2@unl.edu
Phone 402-472-9044
Web Page http://snr.unl.edu/aboutus/who/people/faculty-member.asp?pid=743
Project Information
Title On Basin Residence Time and Annual Hydrology: Development of Annual Hydrology Model of the Sandhills Rivers
Other(s) Erkan Istanbulluoglu, University of Washington, erkani@u.washington.edu; Durelle Scott, Virginia Tech, dscott@vt.edu; Tiejun Wang, University of Washington-Seattle, tjwang@u.washington.edu 
Description

Simple models of annual and mean annual basin runoff and evapotranspration, such as the one proposed by Budyko, are useful for investigating the relationship between river flow and climate, and planning water storage structures in basins where long term streamflow measurements are not available. Such models are often based on the assumption that annual precipitation is in balance with annual runoff and evapotranspiration, and change in water storage of the basin is negligible. In basins where groundwater is the dominant source of streamflow this assumption hardly holds.

In this study first we develop a technique to investigate groundwater residence time to identify time scales over which a simple model of mean annual runoff can be meaningfully used. The model is applied in the Niobrara and Loup Rivers. Second we develop an annual hydrology model by solving the rate of change in basin storage. The runoff component of the model is based on the well-known linear reservoir model and a parameterization to characterize runoff on saturated areas. River water storages and streamflow diverted for irrigation are included as inputs in the model. The model explained as high as 80% of the annual variability of runoff in the Niobrara River at the Sparks gage. The model underscores the importance of saturation overland flow in the basin. Finally we used the model to investigate climate change scenarios, including extreme dry and wet conditions, as well as scenarios for the Medieval Warm Period during which Sandhills were destabilized as suggested by geological evidence.

Project presentation at the 2008 Water Colloquium

Project Support National Science Foundation
Project Website
Report Lenters_Groundwater.pdf
Current Status Published "On the role of groundwater and soil texture in the regional water balance: An investigation of the Nebraska Sand Hills", USA, Water Resour. Res., 45, W10413, doi:10.1029/2009WR007733.
Topic Recreation
Project's Primary Contact Information
Name Laing, Kim (Graduate Student)
Unit School of Natural Resources
Email kmeuhe1@unl.edu
Phone n/a
Web Page
Project Information
Title Assess Extent of Disturbance by Canoeists in Tributaries to the Niobrara National Scenic River
Other(s) Kyle Hoagland, School of Natural Resources, khoagland1@unl.edu 
Description

The Niobrara is a rich and unique ecosystem. Because it is relatively swift and shallow along this reach, the Niobrara is also a popular locale for tens of thousands of canoeists each year. Frequent bottom trampling and bank destabilization can result in a variety of short and long-term changes, including bottom substrate degradation, higher levels of drift including premature drift of aquatic larvae, increased turbidity and sedimentation, and the elimination of sensitive species.

The overall goal of this project is to assess the extent of disturbance by canoeists in tributaries to the Niobrara National Scenic River and its overall impact on stream ecosystem health. This assessment will be used to evaluate resource management practices in these unique habitats, while also serving as a basis for future comparisons to assess habitat degradation.

Ten tributaries, located along the south side of the Niobrara River, were sampled each month May through September. The tributaries were divided into five streams that were potentially impacted from visitors, located upstream, and five streams that were known to have no visitors. A mini-surber sampler was used to collect invertebrates from upstream sections of the tributaries (above the waterfalls with no visitors) and from downstream sections, below the waterfalls. Current velocity, depth, width, and distance from the edge of the tributary were recorded at each location. Water temperature, pH and conductivity were measured and a water sample taken to measure total nitrogen, total phosphorus and turbidity. In June, July and August visitor information was collected by volunteers at each potentially impacted tributary. Each volunteer counted the number of times the tributary was disturbed. This information, along with daily visitor use collected by Fort Niobrara, U.S. Fish and Wildlife Service, was used to calculate the amount of disturbance occurring at each location.

Project Support n/a
Project Website
Report
Current Status Completed
Topic Recreation
Project's Primary Contact Information
Name Shultz, Steve
Unit UNO Real Estate Research Center
Email sshultz@mail.unomaha.edu
Phone 402-554-2810
Web Page http://cba.unomaha.edu/dir/HomePageBio.cfm?id=347
Project Information
Title Economic and Social Values of Recreation on the Niobrara National Scenic River
Description

The goal of this project is to generate objective and accurate economic data and analyses that will allow the State of Nebraska to evaluate an in-stream appropriation on the Niobrara River for recreation purposes. Nebraska in-stream flow laws and regulations as stated in statute 46-2,116 specify that an in-stream appropriation must be in the public interest on the basis of:

  • The econmic, social, and environmental value of the in-stream use or uses including, but not limited to, recreation, fish and wildlife, induced recharge for municipal water systems, and water quality maintenance; and
  • The economic, social, and environmental value of reasonably foreseeable alternative out-of-stream uses of water that will be foregone or accorded junior status if the appropriation is granted.

The economic value of in-stream uses for recreation will involve estimates of both direct expenditures by river recreationists and the value of their use of the Niobrara Scenic River for boating and tubing using a travel cost model. The economic value of reasonably forseeable alternative out-of-stream uses will be determined by estimating the change in economic value of irrigation in the Niobrara River watershed based upon agricultural land sales from 2000 to 2007. The societal values associated with in-stream flows of and recreation on the Niobrara River will also be calculated using a telephone survey.

Project presentation at the 2008 Water Colloquium

Project Support Nebraska Game and Parks Commission
Project Website
Report Niobrara_Values.pdf
Current Status Completed
Topic Sandhills Studies and Modeling
Project's Primary Contact Information
Name Hu, Qi (Steve)
Unit School of Natural Resources
Email qhu2@unl.edu
Phone 402-472-6642
Web Page http://snr.unl.edu/aboutus/who/people/faculty-member.asp?pid=54
Project Information
Title The Missing Term in Surface Water Balance in the Great Plains
Other(s) Jinsheng You, School of Natural Resources, jyou2@unl.edu 
Description

It has been recognized that the surface water budget derived from the NCEP-NCAR Reanalysis and other existing climatic datasets is not in balance in the Great Plains region. This imbalance is shown by large surface evaporation which cannot be supported by source terms in the budget equation. This large surface evaporation is always appearing in calculations from the surface and soil moisture conditions specified in those datasets. This imbalance poses serious uncertainties to diagnostic and modeling studies of energy and carbon balances and to our understanding of atmospheric/climatic processes in this region. An effort aiming at identifying sources causing the water budget imbalance has been underway and some preliminary results have been obtained. A main source of the imbalance arises from the calculation of the surface evaporation. It was found that the surface and soil water specified in those datasets (developed from integrations of both observations and model simulations) is biased because of inaccurate descriptions of the soil properties, particularly the sandy soils in the Nebraska Sand Hills. A revised model with more accurate descriptions of the soils and soil hydrology in the Sand Hills has produced a balance surface water budget in the Sand Hills.

Project presentation at the 2008 Water Colloquium

Project Support Department of Commerce - National Oceanic and Atmospheric Administration (NOAA)
Project Website
Report
Current Status
Topic Sandhills Studies and Modeling
Project's Primary Contact Information
Name Hubbard, Kenneth
Unit High Plains Regional Climate Center
Email khubbard1@unl.edu
Phone 402-472-8294
Web Page http://snr.unl.edu/aboutus/who/people/faculty-member.asp?pid=55
Project Information
Title Assessment of Soil Moisture Dynamics of the Nebraska Sandhills Using Long-Term Measurements and a Hydrology Model
Other(s) Venkataramana Sridhar; David Wedin, School of Natural Resources, dwedin1@unl.edu 
Description Soil moisture, evapotranspiration, and other major water balance components were investigated for six Nebraska Sandhills locations during a 6 year period (1998-2004) using a hydrological model. Annual precipitation in the study period ranged from 330 to 580 mm. Soil moisture was measured continuously at 10, 25, 50, and 100 cm depth at each site. Model estimates of surface (0-30 cm), subsurface (30-91 cm), and root zone (0-122 cm) soil moisture were generally well correlated with observed soil moisture. The correlations were poorest for the surface layer, where soil moisture values fluctuated sharply, and best for the root zone as a whole. Modeled annual estimates of evapotranspiration and drainage beneath the rooting zone showed large differences between sites and between years. Despite the Sandhills' relatively homogeneous vegetation and soils, the high spatiotemporal variability of major water balance components suggest an active interaction among various hydrological processes in response to precipitation in this semiarid region.
Project Support National Science Foundation, High Plains Regional Climate Center
Project Website
Report Hubbard06.pdf
Current Status Published in Journal of Irrigation and Drainage Engineering, September/October 2006, 463-473
Topic Sandhills Studies and Modeling
Project's Primary Contact Information
Name Loope, David
Unit Earth and Atmospheric Sciences
Email dloope1@unl.edu
Phone 402-472-2647
Web Page http://eas.unl.edu/people/faculty_page.php?lastname=Loope&firstname=David&type=REG
Project Information
Title Large Wind Shift on the Great Plains During the Medieval Warm Period
Other(s) Venkataramana Sridhar; James Swinehart, School of Natural Resources, jswinehart1@unl.edu; Joseph Mason, University of Wisconsin, Madison, mason@geography.wisc.edu; Robert Oglesby, School of Natural Resources, roglesby2@unl.edu; Clinton Rowe, Geosciences, crowe1@unl.edu 
Description Spring-Summer winds from the south move moist air from the Gulf of Mexico to the Great Plains. Growing season rainfall sustains prairie grasses that keep large dunes in the Nebraska Sandhills immobile. Longitudinal dunes built during the Medieval Warm Period (800-100 yBP) record the last major period of sand mobility. These dunes are oriented NW-SE and are composed of cross-strata with bi-polar dip directions. The trend and structure of these dunes directly record a prolonged drought that was initiated and sustained by a historically unprecedented shift of Spring-Summer atmospheric circulation over the Plains: southerly flow of moist air was replaced by dry southwesterly flow.
Project Support National Science Foundation
Project Website
Report Loope Wind Shift.pdf
Current Status Published in Science November 2007 318:1284-1286
Topic Water Quality
Project's Primary Contact Information
Name Kolok, Alan
Unit Biology, UNO
Email akolok@mail.unomaha.edu
Phone 402-554-3545
Web Page http://www.unomaha.edu/envirotox/whoiam.php
Project Information
Title Occurrence and biological effect of exogenous steroids in the Elkhorn River, Nebraska
Other(s) Daniel D. Snow, School of Natural Resources, dsnow1@unl.edu; Satomi Kohno, Department of Zoology, University of Florida, kohno@ufl.edu; Marlo K. Sellin, Department of Biology, UNO, msellin@mail.unomaha.edu; Louis J. Guillette Jr., Department of Zoology, University of Florida, ljg@ufl.edu 
Description

Recent studies of surface waters in North America, Japan and Europe have reported the presence of steroidogenic agents as contaminants. This study had three objectives:

  1. to determine if steroidogenic compounds are present in the Elkhorn River,
  2. to determine if sediments collected from the Elkhorn River can act as a source of steroidogenic compounds to aquatic organisms, and
  3. to determine if site-specific biological effects are apparent in the hepatic gene expression of fathead minnows.

Evidence was obtained using three approaches:

  1. deployment of polar organic chemical integrative samplers (POCIS),
  2. deployment of caged fathead minnows, and
  3. a laboratory experiment in which POCIS and fish were exposed to sediments from the deployment sites.

Deployment sites included: the Elkhorn River immediately downstream from a Nebraska wastewater treatment plant, two waterways (Fisher Creek and Sand Creek) likely to be impacted by runoff from cattle feeding operations, and a reference site unlikely to be impacted by waste water inputs. The POCIS extracts were analyzed for a number of natural steroids and metabolites, as well as four different synthetic steroids: ethinylestradiol, zearalonol, 17-trenbolone and melengestrol acetate. Estrogenic and androgenic metabolites, as well as progesterone and trace levels of melengestrol acetate were detected in POCIS deployed at each site. POCIS deployed in tanks containing field sediments from the four sites did not accumulate the synthetic steroids except for ethinylestradiol, which was detected in the aquarium containing sediments collected near the wastewater treatment plant. Fish deployed in Sand Creek and at the wastewater treatment plant experienced significantly elevated levels of gene expression for two genes (StAR and P450scc) relative to those deployed in Fisher Creek. Fish exposed to the sediments collected from Sand Creek had significantly higher levels of hepatic StAR and P450scc gene expression than did fish exposed to sediments from the two other field sites, as well as the no-sediment control tank.

In conclusion:

  1. detectable levels of steroidogenic compounds were detected in passive samplers deployed in the Elkhorn River,
  2. sediments do not appear to be a significant source for steroidogenic compounds, and
  3. site-specific differences were found in mRNA expression among the different treatment groups of fish; however, a functional explanation for these differences is not readily forthcoming.
Project Support Nebraska Game and Parks Commission, U.S. Geological Survey's Section 104b Program as administered by the UNL Water Center, US Environmental Protection Agency Greater Opportunities Fellowship, Dr. Daniel Villeneuve, US Environmental Protection Agency
Project Website
Report Kolok_Elkhorn.pdf
Current Status Published in Science of the Total Environment 2007 388:104-115
Topic Water Quality
Project's Primary Contact Information
Name Kolok, Alan
Unit Biology, UNO
Email akolok@mail.unomaha.edu
Phone 402-554-3545
Web Page http://www.unomaha.edu/envirotox/whoiam.php
Project Information
Title The Watershed as A Conceptual Framework for the Study of Environmental and Human Health
Other(s) Cheryl L. Beseler, Department of Environmental, Agricultural and Occupational Health, UNMC, cbeseler@unmc.edu; Xun-Hong Chen, School of Natural Resources, xchen2@unl.edu; Patrick J. Shea, School of Natural Resources, pshea1@unl.edu 
Description

The watershed provides a physical basis for establishing linkages between aquatic contaminants, environmental health and human health. Current attempts to establish such linkages are limited by environmental and epidemiological constraints. Environmental limitations include difficulties in characterizing the temporal and spatial dynamics of agricultural runoff, in fully understanding the degradation and metabolism of these compounds in the environment, and in understanding complex mixtures. Epidemiological limitations include difficulties associated with the organization of risk factor data and uncertainty about which measurable endpoints are most appropriate for an agricultural setting. Nevertheless, the adoption of the watershed concept can alleviate some of these difficulties. From an environmental perspective, the watershed concept helps identify differences in land use and application of agrichemicals at a level of resolution relevant to human health outcomes. From an epidemiological perspective, the watershed concept places data into a construct with environmental relevance. This project uses the Elkhorn River watershed as a case study to show how the watershed can provide a conceptual framework for studies in environmental and human health.

Environmental sampling is necessary for evaluating exposure to hormone disrupting chemicals (HDCs); however, sampling is not systematic in time or space, nor does it represent the time frame necessary to adequately link it to human disease outcomes. Although data from municipal sources are available and reliable, countless private drinking water wells go untested and unmonitored. These wells may be in areas vulnerable to concentrated reservoirs of contaminants due to the soil type, infiltration rate, runoff potential, organic matter and erodibility coupled with land use in the region and the chemical properties of the contaminants introduced into the environment. The lack of a defined boundary and introduction of exposure heterogeneity is one of the primary reasons why associations to health outcomes cannot be shown in environmental epidemiological studies.

The use of the watershed provides a natural boundary and the potential within this boundary to obtain denominator data. Based on the characteristics of the watershed combined with sampling data, shared exposures can be identified and intermediate hypotheses tested using sentinel markers of exposure in fish and humans. Lastly, comparable groups identified in other watersheds with similar characteristics but different surrounding land uses can be used to replicate findings.

Project Support Department of Environmental, Agricultural and Occupational Health, University of Nebraska Medical Center
Project Website
Report Kolok_Watershed.pdf
Current Status Published in Environmental Health Insights 2009 3:1-10