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Reference Wetlands of USEPA Region 7

2006 to 2008
Research Location: 
USEPA Region 7


Wetlands provide many ecological, economical, and societal services. However, they continue to be severely impacted through human mediated activities. Over half of the wetlands in the United States, and up to 90% of the wetlands in states within the Great Plains region, have been converted. Despite their importance, there have been no regional standards or nutrient criteria developed for use in the monitoring of wetlands in the USEPA Region 7. As a result there are very few baseline data about the physical, biological, and chemical characteristics of wetland ecosystems in the region. To address this issue, the Central Plains Center for BioAssessment (CPCB) initiated the development of a regional wetlands database with the help of the USEPA Region 7 Regional Criteria Technical Assistance Group (RTAG). With the RTAGs help, the CPCB continues its involvement in the development of wetland nutrient criteria for USEPA Region 7. To accomplish this goal we (1) are compiling and completing the regional wetland database with both existing and newly collected data, (2) sampled 68 randomly selected wetlands to obtain a “snap shot” of wetland conditions for inclusion in the regional wetland database, and (3) are working with Region 7 RTAG members to develop a Central Plains wetland reference site selection process. Determining reference conditions of wetlands will support the development of nutrient reference conditions and criteria for wetlands of the USEPA Region 7 and identify relationships between wetland nutrient concentrations and biological responses (e.g. chlorophyll). Results will also allow us to develop and provide recommendations to state and tribal agencies on the selection of reference sites for further characterization within the region.


Click here for a list of wetlands studied.

Site selection: We selected the reference sites by merging in ArcView the National Wetland Inventory (NWI) maps. A 250 m buffer was delineated around each of the 21,683 wetland centroids, and percent reference condition of the buffer plus wetland was determined. We also determined percent of the wetland plus buffer that lies in public land.

Sampling methods: Each site was visited one time to obtain a “snap shot” or synoptic analysis of wetland nutrient conditions. To account for spatial heterogeneity within each wetland site, an integrated water sample was collected along a longitudinal transect that represents the longest distance across the open water area of the wetland. Surface water samples were collected along this transect and combined into a composite sample. The number of samples collected at each site for the composite sample was determined by the size of the individual wetland and the number of available habitat types (open water, aquatic beds, etc.). In situ water quality measurements were obtained using a laboratory calibrated Horiba® U-10 Water Quality Checker. Specific measurements include pH, dissolved oxygen, turbidity, conductivity, air and water temperature, and salinity (by calculation). Secchi transparency will also be obtained. These in situ measurements were taken along the longitudinal transect and averaged for each site.

Analysis, Results, or Reports

The data is in an MSAccess database that will be merged with data acquired from the following sources:

(Follow up - the final database was posted on the R7 wetland nutrient criteria workgroup webpage.)



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