Water Quality Highlights
A three-year water quality monitoring program was completed in 2013 by the former Shuswap Lake Integrated Planning Process (SLIPP). Thanks to this work, there is now an up-to-date, comprehensive baseline on water quality in the region. This is needed for future analysis of water quality trends, and for setting priorities to protect water quality at the source.
Here’s a quick look at the results.
Good News and Bad
THE GOOD NEWS: In most locations in and around Shuswap and Mara Lakes, water quality is good. Most water samples in the SLIPP monitoring program met government safety guidelines for raw drinking water, for swimming and for livestock, fish and wildlife protection.
THE BAD NEWS: In certain lake locations, rivers and streams, high concentrations of phosphorus, nitrogen or fecal coliform bacteria were found.
Nutrients: Too Much of a Good Thing?
Nitrogen and phosphorus are essential to plant growth, but too many nutrients can be a problem.
In a lake ecosystem, an excess of nutrients — especially phosphorus — encourages overgrowth of algae, which can degrade water quality.
There have been two algae bloom of concern recently, on Shuswap Lake in 2008 and Mara Lake in 2010. Both were golden-brown algae. These algae can produce large blooms quickly in springtime when they have access to nutrients, sunshine and a warm surface temperature.
Algae can reduce water clarity, create odours and impair the value of water for drinking, recreation and tourism. Some pathogens in the water can also attach to algae and escape effective water treatment, which can make the water unsuitable for drinking.
Safety guidelines for drinking water and water for recreation focus on fecal bacteria: Escherichia (E. coli). While not directly harmful, E. coli bacteria may indicate that disease-causing bacteria, viruses or parasites are also in the water.
For drinking water, a safe level is ZERO E. coli/100 mL sample. E. coli are found in most lakes and streams naturally from wildlife. There are also human or agricultural sources. That is why ALL surface water should be treated before drinking.
Of particular concern during 2011-2013 water quality monitoring were groundwater sites where some samples showed high levels of nitrogen or phosphorus, or E. coli levels exceeding Canadian Drinking Water Guidelines.
Sources of Nutrients
Most excess nutrients in Shuswap and Mara Lakes come from the tributaries. A study commissioned by the Shuswap Lake Integrated Planning Process in 2013 identified the sources of nutrients in the watershed. It estimated that tributaries (rivers and streams) are the source of over 95% of nutrient-loading into Shuswap and Mara Lakes. Of these, the Shuswap, Salmon and Eagle Rivers are the most significant nutrient sources.
Within those river valleys, the use of land for agriculture creates the greatest nutrient input to the rivers. Nitrogen and phosphorus come from manure and fertilizers that are commonly used in agriculture operations. A reduction in nutrients — especially phosphorus — will have the greatest positive impact on water quality.
Wastewater treatment plants, septic systems and pleasure craft holding tanks (grey water) also contribute phosphorus and nitrogen to the lakes, but not as significantly as previously thought.
A significant, naturally occurring source of nitrogen inputs to the lakes comes from decaying salmon, particularly during years of large salmon runs. When it comes to direct discharges into the lakes, improvements are important. For example, if all wastewater treatment plants discharging into lakes or rivers had tertiary treatment capabilities, this would likely achieve the largest reduction in nutrients from single point discharge sites.
Septic systems around the lakes overall contribute a small fraction of nitrogen and phosphorus loading to the lakes. In Blind Bay, Sorrento, White Lake and Sunnybrae, however, groundwater samples have shown high levels of nutrients and/or E.coli counts – and septic systems may be a contributing source.
For more detail on water quality monitoring results, see the Summary: 2011-2013 Water Quality Monitoring Results for Shuswap and Mara Lakes as well as background reports, available in the Resources section.
WATER QUALITY MUST-READ REPORTS
For highlights of recent water quality monitoring in the Shuswap, see Summary: 2011-2013 Water Quality Monitoring Results for Shuswap and Mara Lakes from the former Shuswap Lake Integrated Planning Process (SLIPP). This is a consolidation and update of a 2011-2012 Summary.
For convenience, the summaries, the 2011, 2012 and 2013 full monitoring reports, and a report on sources of nutrients are available in Resources.