Identification of Stream Temperature Controls
Abstract
Stream temperature is a significant water quality concern in the Pacific Northwest, where warm water can be lethal for indigenous fish species and cold-water refugia are essential for the survival of threatened and endangered salmon. This necessitates regional-scale assessments of water temperature for compliance monitoring. Two methods have been used to observe stream temperatures in the Puget Sound region. The first makes use of a large number of volunteers, who take many measurements at predetermined locations in a brief period of time when high summertime temperatures are anticipated. The second involves the installation of in situ temperature loggers, which continually monitor a small number of selected sites. Differences in the spatial temperature fields generated using these two methods in the Big Soos Creek basin are explored to assess the adequacy of these alternative methods for representing regional stream temperatures. When combined with knowledge of regional geology and land use, it is possible to evaluate the adequacy of the temperature logger network to represent the actual patterns of stream temperatures in the basin. Specifically, the logger network fails to capture a region of the lower reaches of Big Soos Creek where groundwater recharge keeps stream temperatures cooler than predicted from extrapolation of upstream temperatures. Geologic mappings of the region demonstrate that this condition is well-correlated with the presence of glacial outwash, which supplies cool groundwater recharge.
- Publication:
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AGU Spring Meeting Abstracts
- Pub Date:
- May 2002
- Bibcode:
- 2002AGUSM.H41A..20C
- Keywords:
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- 1824 Geomorphology (1625);
- 1860 Runoff and streamflow;
- 1871 Surface water quality;
- 1894 Instruments and techniques