Relationship of Riparian Buffer Type to Water Temperature in the Driftless Area Ecoregion of Minnesota

Abstract
We used the U.S. Fish and Wildlife Service's Stream Network Temperature Model to examine the role of riparian buffer type in mediating summer water temperatures for the reintroduction of brook trout Salvelinus fontinalis into Wells Creek, a tributary to the Mississippi River located in southeastern Minnesota. Stream temperatures measured from 23 July to 3 September 1997 were used to calibrate the model, evaluate existing temperatures, generate simulations for different shade conditions and channel morphologies, and generate simulations for “average” and “warm” summers (we define a warm summer as one that is 2.8°C above the 30-year mean). The simulations indicated that successional buffers (grasses and forbs) provided as much shade as wooded buffers in streams with a width less than 2.5 m. With a low width:depth ratio, the successional buffer vegetation mediated mean temperature as well as the wooded buffer when discharge was held constant. At a discharge characteristic of our study reach, the mea...