2020 Algae bloom in Tappen Bay, photo by Trevor Andrew

The Ministry of Environment recently released a draft report that provides objectives for Shuswap Lake water quality. The document was produced after years of monitoring efforts and extensive collaboration with local Secwepemc communities. Water quality objectives are provincial policy statements that must be considered in decision-making and are designed to protect watershed uses and values.

Report cover

Three Secwepemc communities were able to provide detailed input to the report. The Adams Lake Indian Band stressed how it has a sacred relationship with water, which they recognize, honour and respect because it sustains all life. For the Little Shuswap Lake Band, séwllkwe (water) is also considered sacred and is seen as good medicine for all living things. The Splatsin, whose name comes from their word for riverbank, see themselves as the stewards of their home place and the land is not for anyone to keep, “but only to use respectively and wisely so it will remain healthy for generations to come.”

Monitoring sites

The draft water quality objectives are based on the assessment monitoring data that has been collected since the year 2000 at four points on the lake, the southeast end of Tappen Bay across from Sandy Point, near Marble Point, off Armstrong Point in the main arm, and west of Sorrento near the outflow. At each site, water samples are taken at regular intervals and tested for dissolved oxygen, water clarity, phosphorus, nitrogen, chlorophyll a, total organic carbon and E. coli.

Monitoring results primarily show that the lake water quality is high, except during the spring run-off when the high water flushes nutrients from disturbed land and agricultural operations and for some locations during the summer months. The baseline measurements for all the parameters, which indicate high water quality, became the objectives. Thus the goal for management is to ensure that monitoring test results never go above the baseline numbers.

Most of the lake is oligotrophic, which is characterized by low nutrient concentrations, clear water and low biological productivity. However, both Salmon Arm Bay and Tappen Bay tend to be mesotrophic, because the water typically contains more nutrients. Thus, the objective for phosphorus is 15 μg/L (micrograms per litre) in these bays, whereas it is 10 μg/L at the other locations.

2008 algae bloom in Mara Lake

Phosphorus levels are the primary concern, as high levels can result in algae blooms, which have now occurred twice in Mara Lake (2008 and 2010) and at least once (2020) or more times in Tappen and Salmon Arm Bays. The report lays the blame on agriculture (specifically dairy and poultry farms) for declining water quality, as it contributes over 95% of the nutrient load to the lake, with the Shuswap River delivering the most nutrients, followed by the Salmon River and the Eagle River.

The 2008 algae bloom extended all the way to Blind Bay. It went from orange to green before it dissipated

The government is looking for comments on this draft report before it is finalized. There are definitely some serious flaws in the overall monitoring efforts, the actual report and the management system that is meant to rely on objectives. Testing water quality in two of the sites will always show high water quality because the lake is and will likely always be oligotrophic. Testing near Blind Bay is useful, because of all the septic systems in the South Shuswap and it is critically important in Salmon Arm Bay, because of the persistent amount of nutrients coming from the Salmon Valley. Testing should also be done in Mara Lake, as that is where there have been two algae blooms due to the high volume of nutrients flowing into the Shuswap River.

The 2020 algae bloom also began in Mara Lake near the mouth of the Shuswap River (pictured above), photo courtesy of the Ministry of Environment

Objectives may be useful for the number crunchers, but if and when the numbers are high, there is no plan for addressing the root problems. The government continues to avoid creating strict regulations for farming that limit the spreading of manure and the use of fertilizer. Studies show how farmland in the Shuswap River valley is saturated with high concentrations of phosphorus, and if farmers stopped adding more it would take more than 100 years for these levels to decrease significantly. Thus, despite the setting of objectives, the threat of more algae blooms will continue as long as the fields continue to be treated with manure and fertilizer.

2010 algae bloom in Mara Lake, photo courtesy of the Ministry of Environment


The draft report overall downplays the declining water quality in Shuswap Lake. There are no reported instances of algae blooms prior to 2008. What has changed? The biggest change has been the increase in number of large, industrial like dairy farms that produce massive amounts of manure. Fields are covered with liquid manure, which seeps into creeks and rivers and eventually into Shuswap Lake. Farms often spread the manure on top of snow, which increase the likelihood that it would end up in the lake. Fortunately, this practice has been banned. Soil on these farms has been tested and found to be so saturated with phosphorus, from both manure and fertilizer, that it would take over a century for the levels to decline and only if manure was no longer spread.

Another issue with the report concerns E. coli bacteria. The report claims that lake water is largely free of this dangerous bacteria that has caused deaths elsewhere and yet the beach at Sunnybrae has been closed often due to high levels of E. coli. The report also claims that lake water temperatures are never warm enough to be of concern. However, last year, during the heat dome, the temperature of the water was extremely warm and with climate change, so this could be a problem in the future. Of course the lake is so deep, that whenever there is a strong wind, the lake turns over and the temperature drops.

Another image of the 2010 algae bloom, photo courtesy of the Ministry of Environment

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