PPT Slide
This graph shows the results of a study conducted by John Galli in Montgomery County, MD. The temperature increases dramatically in an urban stream as compared to a rural one.
Copyright 2000, Center for Watershed Protection
Notes:
This impact was highlighted in a study conducted by John Galli of two small watersheds in Montgomery County, Maryland. The first watershed, Lakemont, shown in blue, was below 68 degrees during 100% of the observations that were collected. The Lakemont tributary was undeveloped and is capable of supporting trout. Moving just a few miles away to the White Oak tributary (shown in pink) which is 55% impervious, the stream is much warmer, despite the fact that it is a physically similar watershed. Indeed, 50% of all the observations collected at White Oak were above 68 degrees which is the maximum upper temperature needed to maintain trout. Several readings reached 84 degrees F, well outside the thermal regime necessary to maintain trout, sculpins, and stone flies.