Total Dissolved Gas and Water Temperature in the Lower Columbia River, Oregon and Washington, 2005: Quality-Assurance Data and Comparison to Water-Quality Standards

By Dwight Q. Tanner, Heather M. Bragg, and Matthew W. Johnston

U.S. Geological Survey Data Series 148

Prepared in cooperation with the U.S. Army Corps of Engineers

Spill from dams (here, Bonneville Dam on the Columbia River) increases the concentration of dissolved atmospheric gases in water. Excessive dissolved-gas concentrations can be harmful to fish.

Significant Findings

When water is released through the spillways of dams, air is entrained in the water, increasing the downstream concentration of dissolved gases. Excess dissolved-gas concentrations can have adverse effects on freshwater aquatic life. The U.S. Geological Survey (USGS), in cooperation with the U.S. Army Corps of Engineers, collected dissolved-gas and water-temperature data at eight sites on the lower Columbia River in 2005.

Significant findings from the data include:

• Variances to the Oregon and Washington water-quality standards for total dissolved gas were exceeded at five of the monitoring sites: Camas (11 days), John Day tailwater (3 days), The Dalles forebay (3 days), Bonneville forebay (3 days), and John Day navigation lock (1 day).

• From mid-July to early September, water temperatures were above 20 °C (degrees Celsius) at each of the eight lower Columbia River sites. According to the Oregon temperature standard, the 7-day average maximum temperature of the lower Columbia River should not exceed 20 °C; Washington regulations state that the 1-day maximum should not exceed 20 °C due to human activities.

• Most field checks of total-dissolved-gas sensors with a secondary standard were within ± (plus or minus) 1% saturation. Most of the field checks of barometric pressure were within ±1 millimeter of mercury of a secondary standard, and water temperature field checks were all within ±0.2 °C.

• For the eight monitoring sites in water year 2005, an average of 98.2% of the total-dissolved-gas data were received in real time by the USGS satellite downlink and were within 1% saturation of the expected value, based on calibration data, replicate quality-control measurements in the river, and comparison to ambient river conditions at adjacent sites.

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Contents

Significant Findings
Introduction
Background
Purpose and Scope
Methods of Data Collection
Summary of Total-Dissolved-Gas Data Completeness and Quality
Quality-Assurance Data
Effects of Spill on Total Dissolved Gas
Comparison of Total Dissolved Gas and Temperature to Standards
References Cited

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For more information about the USGS Lower Columbia River Dissolved Gas Monitoring Program, please visit the study Web site.

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