Relations of Tualatin River water temperatures to natural and human-caused factors

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Title Relations of Tualatin River water temperatures to natural and human-caused factors
Creator Risley, John C.
Subject Water quality; Water temperature; Salmon; Trout; Fishes; Fishes -- Effect of human beings on; Nature -- Effect of human beings on; Management; Computer simulation
Spatial Coverage Columbia River; Oregon
Description Aquatic research has long shown that the survival of cold-water fish, such as salmon and trout, decreases markedly as water temperatures increase above a critical threshold, particularly during sensitive life stages of the fish. In an effort to improve the overall health of aquatic ecosystems, the State of Oregon in 1996 adopted a maximum water-temperature standard of 17.8 degrees Celsius (68 degrees Fahrenheit), based on a 7-day moving average of daily maximum temperatures, for most water bodies in the State. Anthropogenic activities are not permitted to raise the temperature of a water body above this level. In the Tualatin River, a tributary of theWillamette River located in northwestern Oregon, water temperatures periodically surpass this threshold during the low-flow summer and fall months. An investigation by the U.S. Geological Survey quantified existing seasonal, diel, and spatial patterns of water temperatures in the main stem of the river, assessed the relation of water temperatures to natural climatic conditions and anthropogenic factors (such as wastewater-treatment-plant effluent and modification of riparian shading), and assessed the impact of various flow management practices on stream temperatures. Half-hourly temperature measurements were recorded at 13 monitoring sites from river mile (RM) 63.9 to RM 3.4 from May to November of 1994. Four synoptic water temperature surveys also were conducted in the upstream and downstream vicinities of two wastewater-treatment-plant outfalls. Temperature and streamflow time-series data were used to calibrate two dynamic-flow heat-transfer models, DAFLOW-BLTM (RM 63.9-38.4) and CE-QUAL-W2 (RM 38.4-3.4). Simulations from the models provided a basis for approximating effluent and riparian-shading sensitivity analyses, and evaluating mitigation management scenarios under 1994 climactic conditions. Findings from the investigation included (1) under "natural" conditions the temperature of the river would exceed the State standard of 17.8 degrees Celsius at many locations during the low-flow season, (2) current operation of wastewater treatment plants increases the temperature of the river downstream of the plants under low-flow conditions, (3) river temperature is significantly affected by riparian shade variations along both the tributaries and the main stem, (4) flow releases during the low-flow season from the Henry Hagg Lake reservoir decrease the river temperature in the upper section, and (5) removal of a low diversion dam at RM 3.4 would slightly decrease temperatures below RM 10.0.
Publisher U.S. Geological Survey
Contributors Unified Sewerage Agency of Washington County, Oregon
Date 1997
Type Text
Format application/pdf
Digitization Specifications pdf file copied from USGS website ( Uploaded into CONTENTdm version 3.7.
Source Risley, John C., 1997, Relations of Tualatin River water temperatures to natural and human-caused factors, Portland Oregon: U.S. Geological Survey Water-Resources Investigations Report 97-4071, 153 p.
Language eng
Rights Management Public Domain, Courtesy of the USGS
Holding Institution University of Utah
Metadata Cataloger Daureen Nesdill; Kristin Willmore
ARK ark:/87278/s65h7f6z
Setname wwdl_er
Date Created 2004-11-03
Date Modified 2005-10-06
ID 1145727
Reference URL
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