Total Dissolved Gas and Water Temperature in the Lower Columbia River, Oregon and Washington, Water Year 2014

Significant Findings

An analysis of total-dissolved-gas (TDG) and water-temperature data collected at eight fixed monitoring stations on the lower Columbia River in Oregon and Washington in water year 2014 indicated the following:

• All 81 TDG sensor laboratory checks that were performed after field deployment were within plus or minus (±) 0.5-percent saturation of a primary standard.
• After 3–4 weeks of deployment in the river, 68 of 75 TDG sensor field checks were within ±1.0-percent saturation of a secondary standard. Six of the field checks greater than ±1.0-percent saturation occurred at the John Day tailwater station, and three of these six checks resulted in periods of deleted data at the station.
• All 77 barometric pressure field checks were within ±1 millimeter of mercury of a primary standard, and all 74 water-temperature field checks were within ±0.2 degrees Celsius of a secondary standard.
• TDG data were considered complete if they were received in real time and were within 1-percent saturation of the expected value on the basis of calibration data, replicate quality-control measurements, and comparison to river conditions at adjacent stations. For the eight monitoring stations, data completeness ranged from 78.2 to 100 percent.
• All quality-assurance values exceed the criteria established by the U.S. Army Corps of Engineers TDG monitoring plan. Criteria for data completeness (95 percent) were met at six of the eight monitoring stations. Deleted data at the John Day tailwater station and missed transmissions at the Camas station resulted in data completeness below criteria.

First posted June 12, 2015