Minnesota Water Resources Conference - Water Resources Center ...

Concurrent Sessions V 1:15–2:45
Track D: Understanding Trout Streams
BOOK OF ABSTRACTS
Wednesday, Tuesday, October 24 28 23
Trout Stream Spring Characterization Methods and Springshed Mapping
Scott Alexander, University of Minnesota, alexa017@umn.edu; Andrew Luhmann, University of Minnesota; E. Calvin
Alexander, Jr., University of Minnesota; Jeffery Green, Minnesota Department of Natural Resources; and Andrew Peters,
Minnesota Department of Natural Resources
Southeastern Minnesota’s karstlands support numerous trout streams. Dye tracing has been the primary tool
for mapping springsheds supporting trout streams. A two-year study funded by the Minnesota Environment and
Natural Resources Trust Fund aims to significantly increase the number of mapped springshed by integrating a
variety of old and new tools.
Techniques used in combination with dye tracing include temperature and discharge monitoring, detailed
structural mapping, chemical and isotopic studies. New methods to define springsheds can be tested against
existing, dye trace defined basins. In previously untraced basins these tools can produce more efficient dye
tracing programs.
Trout streams have been traditionally managed as surface water resources yet are fundamentally supported by
clear, constant temperature groundwater. In karst areas groundwater resources are as vulnerable as surface
waters to human activities. Designing Best Management Practices (BMPs) to protect ground water fed springs
should improve the overall protection of Minnesota’s trout streams.
Stream Flow and Temperature Analysis of the Vermillion River
William Herb, University of Minnesota, wrherb@comcast.net; Ben Janke, University of Minnesota; Omid Mohseni, University
of Minnesota; and Heinz Stefan, University of Minnesota
Stream temperature and stream flow are important parameters for aquatic habitat preservation in river and
stream systems. Water temperature is particularly important for coldwater stream systems that support trout.
Summer base flow conditions with low flows and high water temperatures can be critical for maintaining
trout habitat. Surface runoff from rainfall events can lead to increases in stream temperature, particularly
in developed watersheds. To better understand the interactions between stream temperature, land use, and
climate, an unsteady stream flow and temperature model has been developed for the Vermillion River. This
river is at the southern fringes of the Twin Cities metropolitan area and has a world-class brown trout fishery.
Stream flow was modeled using two existing tools, HEC-RAS and EPA-Riv1. A stream temperature model was
developed at St. Anthony Falls Laboratory, UofM, to model stream temperature response to climate variations
and surface runoff on short time-scales. The 1D model includes advective transport of heat downstream, wateratmosphere
heat exchange and water-sediment heat transfer. The stream temperature model uses simulated
unsteady flows and observed climate data as input. The hydro-thermal response of the stream to surface runoff
during storm events is simulated at 1 hour time steps and distance increments of about 200 m using summer
baseflow conditions as an initial condition. In addition to detailed temperature and flow time series, the model
provides broad scale characterizations of heat transport in the Vermillion, including the relative importance
of groundwater temperature, atmospheric heat transfer, and surface water inputs in determining stream
temperature. The stream temperature model can therefore be used as a tool to determine what management
practices (e.g. stormwater BMPs, bank shading, groundwater conservation) are best to maintain cold water
temperatures for trout habitat.
Minnesota Water Resources Conference, October 27–28, 2008 72