The water quality site on the Columbia River at Birchbank is about 24 km downstream from the community of Castlegar and approximately 25 km north from the international border. The drainage area for the Columbia River at Birchbank is 88,100 km2 (Figures 1 and 2).
The reach of the Columbia River that extends from Revelstoke to Birchbank can be divided into two distinct regions. These are the portions of the river upstream and downstream from the Hugh Keenleyside dam. This dam, located approximately 7 km upstream from Castlegar, separates the Arrow Lakes from the last remaining free-running reach of the Columbia River. Under terms of the Columbia River Treaty, the Hugh Keenleyside dam was built in 1967 to provide water storage for flood control and hydroelectric power generation at facilities in the United States.
The region between Revelstoke and the Hugh Keenleyside dam is characterised by two major lakes (Upper Arrow and Lower Arrow). There are no major tributaries feeding the river system here, but many smaller streams feed into the two lakes and subsequently into the Columbia River.
The Kootenay River is the largest tributary entering the Columbia River between the Hugh Keenleyside dam and Birchbank. The river flow is regulated by a series of dams and reservoirs. The last in this series is the Brilliant Dam (constructed in 1944) which is located three km upstream from the Kootenay-Columbia confluence. Past studies indicate that up to 43% of the mean annual flow of the Columbia River measured at Birchbank comes from the Kootenay River (Butcher, 1992).
Major effluent discharges in this reach of the Columbia River include the Celgar pulp mill (PE 1272) and the City of Castlegar (PE 80, PE 4008). There are also several smaller effluent discharges (e.g., Selkirk College - PE 141) (Butcher, 1992).
The Celgar pulp mill was the oldest Kraft pulp mill (started up in 1961) in the interior of B.C. In the past, it discharged untreated effluent into the Columbia River 3.3 km downstream from the Hugh Keenleyside dam (Butcher, 1992). In 1989, the company proposed building a new facility to replace the old one, incorporating new technologies that would allow them to meet all current and future environmental criteria (Aquametrix Research, 1994). The proposal was approved and construction of the new mill commenced in February 1991. The new mill began operations in June 1993, allowing the original mill to cease operations (Aquametrix Research, 1994).
Effluents discharged from the old mill were characterized by high levels of suspended solids, colour, nitrogen, phosphorus, biochemical oxygen demand (BOD), resin/fatty acids, adsorbable organic halogens (AOX), chlorinated phenolic compounds, and chlorinated dioxins/furans. These discharges were found to be acutely toxic to the population of rainbow trout in the region (Aquametrix Research, 1994).
The new mill has greatly reduced the levels of contaminants in the effluents discharged, effectively meeting provincial and federal permit requirements and regulations. Recent discharges were not acutely toxic to rainbow trout (Aquametrix Research, 1994).
The City of Castlegar has two separate secondary sewage treatment systems, both authorized under Waste Management Act permits. One of the treatment systems discharges effluent into the Columbia River from the north bank, about one km upstream from the Kootenay-Columbia confluence. The other system discharges near the west bank, two km downstream from the Kootenay-Columbia confluence. Available effluent data indicate that discharge levels have remained below permitted maximums (Butcher, 1992; Aquametrix Research, 1994).
Selkirk College discharges secondary-treated sewage into the Columbia River approximately 0.5 km downstream from the Columbia-Kootenay confluence.
This report assesses data from the Ministry of Environment, Lands and Parks (1987-95 and 1968-78 for total phosphorus) and Environment Canada data (1983-95). More recent data have been included for water quality indicators exhibiting trends or concerns: through 1997 for total aluminum, and through 1996 for total iron, total phosphorus, and total dissolved gases. The provincial EMS station number is 0200003 and the federal ENVIRODAT station number is BC08NE0005. Flow is plotted in Figure 3, showing 1983-94 data from Water Survey of Canada station BC08NE049 at Birchbank. Water quality data are plotted in Figures 4 to 55.