| Abstract/Description or Keywords |
Since the middle 1980s the two major environmental agencies in British Columbia, Environment Canada (EC) and the B.C. Ministry of Environment, Lands and Parks (BC MoELP), have monitored water quality at sites on the Fraser River and major tributaries. A number of sites are maintained through a Federal- Provincial water quality monitoring agreement. These monitoring data were examined for spatial and temporal trends in the record from 1985-1991. Analytical methods included graphical analysis and summary and statistical analysis. Both non-parametric (Kendall’s Tau, Van Belle statistics and Sen Slope estimation) and parametric (regression modelling) techniques were used in the statistical assessment of trend. Sufficient data were available for seven sites within the Fraser River Basin; the mainstem Fraser River at Red Pass, Hansard, Marguerite and Hope; the Nechako River near Prince George; the Thompson River near Spences Bridge and the Salmon River near Salmon Arm.The suite of parameters being monitored include physical measurements (conductivity, colour, temperature, PH, residue), dissolved ions, dissolved nutrients, total metals and coliform bacteria. No data on organochlorine compounds were available for trend assessment. A total of 27 variables from the Environment Canada data and 15 from the BC MoELP data were studied for trend. Comparison of upstream-downstream values of water quality variables on the mainstem Fraser River demonstrated the influence of surface geology on the composition of water at particular sites. In addition, the effect of major discharges such as pulp and paper mills and municipal sewage treatment facilities were evident as elevated concentrations of certain dissolved ions (chloride, sodium) and fecal coliform bacteria at downstream sites. Statistical analyses of trend by non-parametric and parametric methods indicated a variety of patterns. Probably owing to the relatively short period of record (five years), results of the two methods differed somewhat. Instances of agreement of trend by both methods are considered to be relatively robust. Of particular interest are increasing trends in potassium, sulphate, arsenic, nitratehtrite and orthophosphorus on the Fraser at Marguerite which may be attributable to upstream discharges. A declining trend in fecal coliform numbers at Marguerite was also detected, suggesting a favorable effect of improvements in sewage treatment upstream of the site. Combined upstream discharges are probably responsible for a clear increasing trend in dissolved chloride in the Fraser River at Hope. Other trends not clearly attributable to anthropogenic cause are considered in the report. This represents a first effort at summarizing the joint Federal-Provincial water quality information from the upper Fraser Basin, and results will provide direction for future efforts. |
