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OR164 Temperature Modeling Tualatin River



(shaded study area map) Study area

PROJECT CHIEF: John C. Risley

LOCATION: Tualatin River

PROJECT EXTENT: Principally Washington County

TOTAL AREA IN SQUARE MILES: 712

BACKGROUND

As part of an overall program to protect the health of aquatic ecosystems in Oregon, regulatory agencies have imposed stringent guidelines on allowable temperature modifications to water bodies. There is clear evidence that fish survival decreases markedly as water temperatures warm past a critical theshold, particularly during sensitive life-stages of fish. In the Tualatin River, water temperatures periodically reach and surpass the critical theshold for cold-water fish during the low-flow season in the summer and fall months. During these times, it is important that human-caused increases in water temperature are minimized.

Urban runoff, effluent from WWTPs, and incomplete riparian vegetation in the drainage basin may contribute to warm water temperatures in the Tualatin River. However, these impacts are not well characterized or quantified.

OBJECTIVES

Quantify the temporal and spatial patterns of water temperatures in the main-stem Tualatin River and the mouths of major tributaries; determine the relation of water temperatures in the Tualatin River and major tributaries to climatic condiditons, seasonal and diel variations, and human-caused factors; and quantify the potential effectiveness of urban and agricultural management strategies for controlling impacts on stream temperatures during the base-flow season (May through October).

APPROACH

The study approach includes the following three elements: (1) collect water temperature, meteorological, discharge, and channel geometry and shading data to support model development and calibration; (2) calibrate and validate a dynamic water-temperature model of the Tualatin River (Scoggins Creek Dam to the Lake Oswego Dam); and (3) use the model to test various management scenarios to remediate water temperature problems associated with human activities in the basin.

REPORTS

OFR 96-315. Water-Temperature, Specific-Conductance, and Meteorological Data for the Tualatin River Basin, Oregon, 1994-95, by John C. Risley and Micelis C. Doyle. Abstract

WRIR 97-4071. Relations of Tualatin River Water Temperatures to Natural and Human-Caused Factors, by John C. Risley.

WRIR 00-4071. Effects of Hypothetical Management Scenarios on Simulated Water Temperatures in the Tualatin River, Oregon, 1998, by John C. Risley.


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Last modified: 12/19/00