| Abstract/Description or Keywords |
Ninety-eight percent of the Pend d’Oreille River watershed lies in the United States. The Canadian portion of the river is about 22 km long, and is located just above the US Border, southeast from Trail, B.C. (see map). This assessment is based on five years of water quality data collected between December 1997 and May 2003. CONCLUSIONS: • The water was soft to moderately hard, with a low sensitivity to acids, and largely within the optimum aesthetic range for drinking water. • Turbidity was low due to upstream reservoirs and Lake Pend Oreille, but filtration plus disinfection would be needed prior to drinking water use. • Metal levels were low, except for aluminum, which exceeded the draft Canadian water quality guidelines for aquatic life at times, but this is not considered to be serious. • Water temperatures exceeded aquatic life and aesthetic drinking water guidelines during the summer, when the water was warm enough for water-contact recreation, such as swimming. Lake Pend Oreille and the reservoirs on the river probably caused the higher than normal temperatures due to increased solar heating. • The water quality at the US Border and Waneta stations was similar, with the exception of extractable cadmium. Cadmium levels at Waneta were higher than at the US Border, and exceeded aquatic life guidelines during 1998-2001, although there was an improving trend over time, possibly due to declining river flows and turbidity levels. Backwater from the Columbia River was probably not a factor in the 1998-2001 cadmium levels at Waneta that exceeded guidelines. RECOMMENDATIONS: • Monitoring should continue in the Pend d’Oreille River at US Border as a downstream station for influences in the US and as reference station for the Pend d’Oreille River at Waneta. • An investigation of the sources of cadmium between the US Border and Waneta stations should be undertaken, if aquatic life guidelines continue to be exceeded at Waneta. • The sample collector should be encouraged to record any indications of backwater during sampling at the Pend d’Oreille River at Waneta station. • The minimum detectable limit for extractable cadmium should be reduced to 0.002 _g/L or less, when the technology becomes available, to improve the reliability of the measurements. |
