Estimating Water Temperatures in Head-Water Streams Within Brook Trout Habitat

Brook trout are a native and keystone species in Pennsylvania and often used as an indicator of environmental quality due to their sensitivity to water temperature. In order to analyze the potential habitat quality for brook trout, water temperature data is required. Land use and terrain variables have been used to predict brook trout presence, but it is clear that the anthropogenic impact of climate change, as well as mining, drilling, and development will affect our ability to predict fish populations. We are using trout population data collected in a total of 615 first- and second-order tributaries within north-central and central Pennsylvania. The USGS collects stream water temperature data on larger order streams, but not on the first- and second-order streams we are looking at. Beginning with the two assumptions that A) first order streams are fed primarily by springs and B) annual average air temperature influences spring water temperature, we have designed a model to predict water temperatures within first order streams based on the site elevation as well as its local, long term weather measurements. A random group of 60% of sites with water temperature measurements were used to calibrate the regression equations between elevation, site location, and water temperature. The remaining 40% of sites were used as a comparison group to determine the predictive ability of the model. We aim to determine the relationship between estimated water temperature and brook trout populations. Streams containing brook trout are given a higher level of environmental protection than streams without the species in Pennsylvania and of the 62,725 streams in PA, only 8,224 of them have been sampled by the Pennsylvania Fish and Boat Commission. Over 53,000 streams remain to be sampled. Our goal is to accurately predict water temperature which will be helpful to the PFBC and allow for targeted selection of sampling sites for biological monitoring