Summary of Surface Water Quality Sampling on Sumas River and Tributaries
Non-point source (NPS) water pollution is the release of pollutants to surface / ground water from activities that occur over a large area, and results from water flowing over (and through) the land surface and transporting contaminants (e.g. pathogens, oxygen depleting substances, suspended materials, toxic chemicals) and debris into water bodies. NPS pollution is recognized as a major cause of water pollution in British Columbia and it represents a significant threat to water resources.
In 2001, the Ministry of Environment (MoE), Environmental Quality Section (Lower Mainland Region) commenced a surface water quality trend monitoring program (Trend Monitoring Program). The objective of the Trend Monitoring Program is to assess impacts of NPS pollution on aquatic environments and to identify trends in water quality (i.e., improving, unchanged, declining) at selected sites within the region. Trend monitoring stations were selected to obtain water quality data at sites representative of particular NPS pollution sources (e.g. urban development, agriculture, forest harvesting). The Trend Monitoring Program also provides a measure of the efficacy of strategies implemented to address NPS pollution, and is intended to facilitate better decision making regarding land use practices and the protection of surface water quality.
In November 2001, MoE established a water quality trend monitoring station at Saar Creek in Abbotsford, BC. Saar Creek, a tributary to the Sumas River, is located in an area of the Fraser Valley that has been intensively utilized for agricultural activities since the 1950s. The intent of the Saar Creek trend monitoring station is to identify trends in water quality in a system that is influenced by agricultural NPS pollution. Approximately 57 square kilometres of the Sumas Prairie is utilized for agricultural activities such as dairy, hog, poultry and produce. The agricultural land base of the Sumas Prairie has not increased significantly since expansion of agriculture following the draining of Sumas Lake; however, the intensity of operations has increased dramatically with a trend toward densification of livestock operations. The intensification of livestock operations has resulted in more animal waste being generated (and disposed of) on a land base that may not be capable of assimilating the waste. Agricultural census data and waste management survey data suggests that over 50 percent of the agricultural land base in the Sumas watershed receives excess nutrients that potentially contribute to water pollution.
The general objective of this report is to summarize historical water quality information within the lower reaches of the Sumas River watershed to provide context to the above-described Saar Creek Water Quality Trend Monitoring Program. Specific objectives of this report are to:
- summarize findings of previous water quality studies undertaken within the Sumas River watershed;
- summarize results of historic surface water quality sampling undertaken by MoE in the lower Sumas River watershed;
- discuss potential impacts characterized by MoE sample results on designated water uses by comparing results to federal and provincial water quality guidelines / objectives; and
- offer recommendations to reduce water quality impacts caused by non-point source pollution.
Historical data collected by MoE indicates general water chemistry parameters such as water
temperature and dissolved oxygen appear to be the two most important parameters
with regard to impacts on aquatic species in the Sumas River watershed. Water
temperatures were elevated, and occasionally exceeded Water Quality Guidelines,
during the summer months. Dissolved oxygen levels were reduced, and occasionally
exceeded Water Quality Objectives, in both the summer and fall months. During
the fall months, low dissolved oxygen levels are likely a combination of
increased oxygen demand associated with improper agricultural waste management
practices (i.e., introduction of oxygen consuming wastes) as well as oxygen
demand resulting from decomposing aquatic vegetation. Elevated levels of fecal
coliforms occur throughout the year, suggesting that management of agricultural
waste in the watershed is a persistent problem and not just limited to the fall and winter months (when land application is precluded and storage capacity may be limited). Fecal coliforms are not a concern with regard to impacts on aquatic species, but their presence typically indicates surface waters are receiving nutrient inputs (e.g., nitrogen, phosphorous). Nutrient enrichment can have either direct impacts (i.e., ammonia and / or nitrite-nitrate toxicity) or indirect impacts (e.g., eutrophication) on aquatic species. It should be noted that the Abbotsford aquifer, a source of drinking water, is located in the study area and land use activities that impact on surface water quality may also impact on ground water quality.
It is important recognize that water quality sampling results summarized in this report are simply a snapshot of water quality conditions at the time of sampling and results are not necessarily reflective of "mean" water quality conditions; accordingly, assessment of water quality trends and / or impacts is precluded. However, data indicates water quality conditions have potential to impact on designated water uses and the commencement of automated water quality monitoring on Saar Creek will better characterize water quality conditions.
The complete Sumas water quality report is available here (PDF/1.92 MB/47 pages).
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