The Rideau Valley Conservation Authority rated the water quality of Upper Rideau Lake as poor in its 2014 Watershed Report (data collected from 2005 to 2014). Contributing factors to these ratings include elevated nutrient concentrations, periods of reduced oxygen availability, clear water, and occasionally elevated pH levels. High nutrient concentrations are part of the natural aging process of a lake. In this case, aging may be accelerated due to a high runoff of nutrients from residential shoreline areas, as well as areas of drowned land resulting from the construction of the Rideau Canal. High nutrient concentrations have enabled the excessive growth of aquatic plants and algae blooms.
Westport Sewage Discharge In April 2014, The Village of Westport dumped 24 million liters (63 million gallons) of untreated sewage into Upper Rideau Lake following a roughly 3-year-long collapse of their sewage treatment system. With a sewage lagoon ready to burst, millions of liters were shipped away for treatment, while two emergency discharges of over 12 million liters (31 million gallons) went directly into the lake, fueling blue-green algae growth. Before 1996, the Village of Westport had no treatment plan in place and would dump untreated sewage twice annually into the lake. In 2018, the Village of Westport completed a Large Subsurface Disposal System (LSSDS) costing roughly $3,000,000 to treat the sewage. As of March 2019, there have been no discharges for the past 12 months.
Blue-Green algae concerns In August 2014, toxins were confirmed to be present in
blue-green algae blooms. Leeds, Grenville & Lanark District Health Unit issued a public health notice warning not to drink the lake water or allow pets or livestock to do so. This outbreak can be attributed to the sewage dump, erosion, high spring runoff, and changes in the
zebra mussel population among other causes. ==Sustainability==