State of the Minnesota River Summary of Surface Water Quality Monitoring 2000 The purpose of this Summary Report is to consolidate surface water quality monitoring information collected in the Minnesota River Basin for the calendar year 2000. This Report pulls together data collected by multiple agencies and organizations and presents the data in a fashion that allows for comparison between some of the major tributaries and mainstem sites in the Minnesota River Basin. This initial attempt to summarize annual water quality data collected by multiple agencies falls short in that not all tributary data were able to be included in the report. Noticeably lacking are data from tributaries located on the Lower Minnesota River between St. Peter and the confluence with the Mississippi River at Fort Snelling. Previous work has indicated that this portion of the basin contributes a sizable portion of the nonpoint load to the Minnesota River. Although monitoring stations exist in this portion of the basin, at the time this report was being assembled, some organizations had not finalized data analysis for the year 2000. It is expected that the 2001 Summary Report will include data from some of these missing watersheds or stations. In addition, this Report does not include data from many of the smaller tributaries and field scale evaluations occurring within the basin. This Report also helps fulfill the overall mission of the Minnesota River Basin Data Center, which is to inventory, develop, retrieve, interpret and disseminate information on topics that impact the environment, economy and communities within the Minnesota River Basin. This mission was first articulated by the Citizens Advisory Committee in a series of recommendations to Minnesota Pollution Control Agency (MPCA), and later by the Minnesota River Basin Joint Powers Board. This report is not related to any state mandates or requirements and all organizations and agencies participated voluntarily. The most comprehensive study of water quality in the Minnesota River Basin, the 1994 Minnesota River Assessment Project (MRAP), concluded that the Minnesota River is impaired by excessive nutrient and sediment concentrations. Since the publication of MRAP, several organizations throughout the basin have taken responsibility for collecting additional data to better define tributary characteristics and learn more about how these tributaries affect the condition of the Minnesota River. In many parts of the basin, this information is used to target implementation practices that reduce nonpoint source pollution, thereby improving the overall health of the Minnesota River. Local watershed projects are supported mainly by Clean Water Partnership grants administered by the MPCA. Much of the remaining data presented in this Report are provided through monitoring programs of the Minnesota Department of Agriculture and Metropolitan Council Environmental Services with contributions from the United States Geological Survey (USGS) and the Minnesota State Climatology Office. 1 A secondary purpose of this Summary Report is to provide a forum for continued discussion and improvement of the methodologies used by various organizations to collect and interpret physical and chemical water quality data. Presently, within the Basin, slightly different methodologies are used to collect and analyze data. By documenting and assessing current methodologies, we can begin to identify those of greatest utility and hopefully improve efficiencies and reduce costs. More importantly, adoption of a standard set of methods will allow us to draw more meaningful and accurate water quality comparisons across the basin. This, in turn, should help direct limited resources to areas of greatest need. Preparation of this Summary Report is a joint venture of the Metropolitan Council Environmental Services, Minnesota Department of Agriculture, Minnesota Pollution Control Agency, and the Water Resources Center at Minnesota State University, Mankato. The report is posted on the Minnesota River Basin Data Center web site at http://mrbdc.mankato.msus.edu/ to allow wide access and opportunity for review and comment on its content. Contributors Data to compile this report were submitted and reviewed by representatives of several organizations including: Brown-Nicollet-Cottonwood Clean Water Project Chippewa River Watershed Project High Island Creek Watershed Assessment Project Martin County Environmental Services Metropolitan Council Environmental Services Program Minnesota Department of Agriculture Surface Water Monitoring Program Minnesota Pollution Control Agency, Mankato Office Redwood-Cottonwood Rivers Control Area Watonwan River Clean Water Partnership Project Water Resources Center -Minnesota State University, Mankato The Authors would also like to acknowledge the USGS for much of the flow data that was utilized in the completion of this Report. They are a valuable resource for many organizations throughout the Minnesota River Basin. To submit comments or questions, please send them to: Patrick Baskfield (MPCA) 507-389-1648 Robert Finley (WRC-MSU) 507-389-5492 Heather Offerman (Met Council) 507-344-0145 Bill VanRyswyk (MDA) 507-389-5772 2 2000 Results This section of the 2000 Report presents results from many of the current monitoring projects in the Minnesota River Basin. The discussion presented attempts to evaluate differences in reported results, and in some instances, the methodologies used to collect or compile the results. Most of the data were collected and compiled by the respective monitoring organizations. Map 2.01 presents the locations of the monitoring stations discussed in this Report. Tables and graphics are set up to allow comparative review of the data and are organized from upstream to downstream locations along the Minnesota River. Year 2000 Runoff Runoff is the part of precipitation which appears in rivers and streams, including baseflow, storm flow, flow from ground water, and flow from point sources. Essentially, it is all the flow passing a particular location on the river. By evaluating runoff, comparisons can be made of the relative amount of water coming out of the individual watersheds. To calculate monitoring season runoff, the total flow volume or the amount of water which came past the station during the monitored period is calculated and converted to acre-inches of water. This number is then divided by the total number of contributing acres to determine inches of runoff. Conceptually, this is equivalent to redistributing all the flow out equally over the watershed, then measuring that depth in inches. Typically, the more precipitation that occurs in a watershed, the more runoff there will be. However, the timing and intensity of precipitation, antecedent soil moisture conditions, soil types, land slopes, land use, as well as other factors, can dramatically influence the final runoff number. By evaluating runoff, as well as the concentration of chemicals of interest, we develop a better understanding of individual watershed behavior, which then provides a better platform for comparing different watersheds. The assessment of runoff is particularly important in the Minnesota River Basin because runoff tends to increase as one moves from the western portion of the basin eastward, due to geographical differences in precipitation. A review of data from the State Climatology Office indicates that much of the Le Sueur River Watershed, and a portion of the Blue Earth River Watershed, experienced above normal precipitation during 2000 (see Map 2.02 and Map 2.03). Totals ranged from two to six inches above normal. Generally, those watersheds south of the Minnesota River experienced normal or above normal precipitation levels, while those north of the River were at or below normal precipitation levels. The precipitation total (Map 2.02) reflects the general west to east trend of increasing precipitation. Map 2.02 indicates the western watersheds received roughly 20-28 inches of precipitation during 2000, with runoff volumes of approximately 1-2 inches, while watersheds in the eastern part of the basin received approximately 28-36 inches of precipitation with runoff volumes ranging from 4-8 inches. The 2000 monitoring season runoff values for the participating watersheds were almost all below the 15-year average with the exception of the Le Sueur River Watershed, 3 which was approximately one inch more than the 15-year average. Figure 2.01 presents the inches of runoff from each of the respective projects, and the 15 year monitoring season (April through October) runoff average using a combination of project and United States Geological Survey (USGS) data. Map 2.02 Map 2.03 An evaluation of long-term USGS flow data for the Minnesota River at Mankato, the Blue Earth River at the Rapidan Dam and the Le Sueur River near Rapidan reveals a significant trend of increasing annual runoff over the last 60 years as presented in Figure 2.02. An analysis of long-term flow trends for the Minnesota River (Mallawatantri and Mulla, 1998) found about 70% of the increased flow was due to climatic changes, with the rest due to non-climatic effects. The most likely sources for these non-climatic effects include drainage of wetlands, agriculture drainage, channelization of streams, loss of floodplains, changes in vegetation and cropping systems, and expansion of urban areas. 4 Figure 2.01: 15 Year Monitoring Season Runoff Average Comparison with 2000 Comparison of 2000 Runoff with 15 Year Average MN R.- St Peter 7 Mile Cr. LeSueur Blue Earth Watonwan MN R.- Judson Little Cottonwood 15 Year Avg. Monitoring Season Cottonwood Runoff 4/1 to 10/31 (in) Redwood Inches of Runoff - 2000 monitoring season Chippewa 0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 Runoff (in) Source: USGS flow records and Project data Figure 2.02: 2000 Calendar Year Annual Runoff ANNUAL RUNOFF TREND (Calendar Year, USGS Data) 25.00 MN @ MANKATO BLUE EARTH 20.00 LESUEUR Linear (MN @ MANKATO) Linear (BLUE EARTH) 15.00 Linear (LESUEUR) 10.00 INCHES OF RUNOFF 5.00 0.00 1938 1948 1958 1968 1978 1988 1998 YEAR 5 Monitoring Season Monitoring season length is an important variable to consider when evaluating the reported data.