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Table 7. Continued. Historical Scientific name Common name data Underhill Ammocrypta clara Western sand darter x x Etheostoma cae1Uleum Rainbow darter a X X E. exile Iowa darter a X X E. flabellare Fantail darter a X X E. nigTUm Johnny darter a X X E. zonale Banded darter a X X Perea {lavescen8 Yellow perch a X X Percina caprodes Logperch X X P. maculata Blackside darter a X X P. phomcephala Slenderhead darter a X X Stizostedion canadense Sauger a X X S. vitreum Walleye a X X Aplodinotus gmnnien8 Freshwater drum a X X aFound at 45 reference sites in 1990. The poor biological conditions, as expressed by the mI, of so many selected reference sites indi- cates that there may be a problem with either the sites or the scoring. Most of the low scores occurred at sites in streams with a drainage area less than 500 km2. The sites chosen may not have been good reference sites. However, most of the Minnesota River headwater streams have been altered exten- sively, and these sites probably represent some of the best existing conditions in the basin. Also, some of the metrics used may not be applicable to small streams. In 1991 and 1992, 37 headwater streams (minor watersheds examined by the Land Use Section) were sampled. Additionally, two major tributaries, the Redwood and Blue Earth rivers, were sampled longitudinally. Sampling on the major tributaries began at the mouth and continued upstream to near the source of sustained flow and included minor tributaries. The objective of this sampling was to determine the longitudinal IBI scores and to relate these scores with resource conditions in terms of habitat, water chemistry, and surrounding land use. Data Management Subcommittee Modeling Mathematical models can be used to evaluate the cumulative effects of nonpoint source loadings from surface runoff by simulating pollutant trans- CHRISTOPHER M. KAVANAUGH 19 port through the river system, pollutant interac- tions, biochemical transformations, and the over- all effect on the river's water quality. A comprehen- sive model is being developed using hydrological, land use, and water quality data collected in the Minnesota River watershed. This model will be used as an analytical tool for evaluating the spatial and temporal loadings from nonpoint source pollu- tion and their effect on water quality in the Min- nesota River. The Hydrologic Simulation Program-FOR- TRAN, supported by the U.S. Environmental Pr0- tection Agency Center for Exposure Assessment Modeling (Ambrose and Barnwell 1989), will be used to simulate the effect of non point source load- ings in the mainstem. The Hydrologic Simulation Program-FORTRAN is a comprehensive model of watershed hydrology and water quality that inte- grates runoff processes from land surfaces with the instream physical and chemical water quality processes. The model is designed to simulate a time series of runoff flow rate, sediment load, oxy- gen-demanding organics, and nutrient concentra- tions, along with a time series of water quantity and quality at any point in the watershed. Model output can be processed through a frequency and duration analysis routine for summation and evaluation of the fate and transport of pollutants through the river system. Because the Hydrologic Simulation Program-FORTRAN is a general pur- pose model, its output can be used to support more specialized hydrodynamic models, such as the Water Analysis Simulation Program, for closer examination of special water quality situations.