Cooperator: Wisconsin Department of Natural Resources
Project Chiefs: David J. Graczyk; Dale M. Robertson
Location: Statewide
Project Number: 9KP43
Period of Project: March 2001–June 2005
Problem
Excessive nutrient (primarily phosphorus and nitrogen) loss from the watershed is frequently associated with water-quality problems in Wisconsin’s water bodies. The implementation of the WDNR’s proposed agricultural performance standards and prohibitions should decrease the risk of excessive nutrient loss from croplands and livestock operations. Implementation of TMDLs and the enforcement of phosphorus criteria would also reduce the problems caused by nutrients. The expected water-quality improvements due to the application of agricultural performance standards may vary due to possible differences in nutrient responses in each water body dependent upon where the stream is located. In order to evaluate the environmental benefits of the proposed performance standards and phosphorus criteria, sufficient data need to be collected in various types of streams to define the nutrient response.
Objective
The objectives of the project are to: (1) describe the water quality and biological communities in streams throughout the state, (2) determine how phosphorus and nitrogen concentrations impair the biological integrity of streams, (3) develop a database that can be used to refine the phosphorus criteria for Wisconsin streams, (4) determine how watershed characteristics affect the relations between phosphorus and nitrogen concentrations in streams and the biological integrity of the streams, and
(5) improve our biological assessment of nutrient impairments by developing a nutrient index of biological integrity.
Approach
The approach for the project is to collect water-quality and biological-community data from streams throughout the state and statistically determine if significant relations exist between a stream’s nutrient concentrations, biological integrity, and watershed characteristics. Multivariate statistical analyses will be used to sort out the importance of the many different variables. Since these nutrient relations are expected to vary with stream size and the location of the stream in the state, streams will be grouped by size, and by four nutrient ecoregions and four nutrient zones. Streams will be divided into wadeable and non-wadeable streams.
The variables in the statistical analysis will include indicators of biological integrity, habitat characteristics, nutrient concentrations, and specific watershed characteristics. The biological indicators will include fish abundance and diversity, macroinvertebrate diversity, and periphyton biomass. Water samples collected from the stream will be analyzed for total phosphorus, dissolved phosphorus, nitrate, total Kjeldahl nitrogen, ammonia, turbidity, conductivity, and suspended chlorophyll a. Watershed characteristics will include drainage-area size, stream gradient, climate data, land use, annual runoff, surficial deposits data, and soil characteristics types.
Approximately 160 small streams will be monitored in the first year of the study. Approximately 80 larger wadeable streams will be monitored in the second year of the study and approximately 40 larger non-wadeable larger streams will be sampled in the third year of the study. The fish and habitat data in the wadeable streams were collected using similar protocols at all sites and the data are stored in a readily accessible database.
A total of six water-quality samples will be collected between the months of May and October at each site. A flow measurement will be collected at the time of the water-quality grab sample.
Progress (to June 2004)
Water quality and biological community data were collected at 158 small wadeable streams in 2001, 78 larger wadeable streams in 2002, and 5 small wadeable and 40 large non-wadeable streams in 2003. Samples were analyzed for nutrients and chlorophyll a. Field measurements included stream discharge, water temperature, dissolved oxygen, pH, turbidity, conductance, and stream clarity. Most of the sites were sampled for attached algae, diatoms, and macroinvertebrates by the Wisconsin Department of Natural Resources. All data collected were summarized and published in “Water Resources Data–Wisconsin, Water Year 2001, 2002, and 2003.”
Preliminary analysis of the wadeable streams has been conducted and presented at the Midwest Surface Water Monitoring and Standards (SWiMS) Conference in Chicago, Ill., in 2003 and at several RTAG meetings with the USEPA in Chicago, Ill.
Plans (July 2004–June 2005)
Complete the analysis examining the relations between watershed characteristics and water quality, between water quality and diatom communities, between water quality and macroinvertebrate and fish communities, and the analysis examining the interrelations between all aspects of water quality and biological integrity of streams. A final report will be written describing the impact of phosphorus and nitrogen concentrations on the biological integrity of wadeable streams in Wisconsin. Preliminary analysis of the data collected on the non-wadeable streams will be started. |
