South Nation WatershedSurface water and groundwater quality can be influenced by factors such as the terrain, the time of year, and the type of sewage treatment plants and industry in the surrounding watershed. Common sources of groundwater pollution may include landfills, improper use and disposal of pesticides, agricultural and residential fertilization, improper disposal of animal wastes and industrial leaks and spills.

Nitrate Levels in the Watershed

Nitrate is a form of nitrogen that is commonly associated with fertilizers and fecal contamination from septic systems, sewage treatment plants and manure spreading activities. It is one of the most common pollutants of groundwater in rural areas and a concern because of its affects on the health of children and livestock.

In the South Nation River watershed, nitrate levels are well below the Provincial Water Quality Objective (PWQO) of 10 mg/L. Trends do show an increase in nitrate concentrations in all parts of the South Nation River over the last 40 years. This increase may reflect the increasing demands placed on sewage treatment plants and/or increases in the number and density of septic systems in our watershed as our communities continue to grow.

Phosphorus Levels in the Watershed

Phosphorus is a nutrient commonly associated with fertilizers, detergents and water softeners. It is a pollutant of concern because of its relationship to excessive algal blooms and eutrophication.

In the South Nation River watershed, average total phosphorus concentrations exceed the PWQO (0.03 mg/L) by 300%. Trends show a dramatic decrease in total phosphorus concentrations, especially between the 1960’s and 1980’s. This decrease can be attributed to the construction or improvement of sewage treatment lagoons in Embrun, Casselman and Winchester, to the decision to restrict phosphate concentrations in detergents and to improved land and agricultural management.

Turbidity Levels in the Watershed

Turbidity is a measure of the cloudiness of water caused by minute particles floating in the water, in much the same way as smoke in the air.

Turbidity levels in the South Nation River exceed the PWQO of 1 FTU. (FTU or Formazen Turbidity Unit is the unit of measurement for turbidity). In the lower watershed average turbidity levels often exceed 25 FTU, thus resulting in greater difficulty and expenses associated with drinking water treatment. Trends in turbidity remain fairly constant and are on par with other agricultural rivers in southern Ontario. This suggests that the main sediment load in the river arises from a combination of soil erosion from fields and stream banks. Spikes in turbidity levels occur fairly regularly in the South Nation River watershed and are caused by landslides of the unstable clays found between Casselman and Plantagenet.

Microbiology in the Watershed

The microbiological aspects of water quality focus on the amount of bacteria associated with fecal matter found in a water sample. Since it is nearly impossible to test for all these bacteria, the most practical approach is to test for a series of easily observed fecal indicator species.

In the South Nation River bacterial sampling has shown that our waters exceed the PWQO for agricultural irrigation (100 counts/100 mL) in almost all samples taken in the last 30 years. The river performs better with respect to the PWQO for swimming and recreational activities (200 counts/100 mL) with all but two samples taken between 2000 - 2004 below this objective. The highly variable nature of bacterial sampling makes it very difficult to make definitive conclusions.

Benthic Invertebrates

South Nation Conservation has recently started sampling benthic invertebrates (bottom-dwelling insects) as an additional indicator of water quality and ecosystem health.

Groundwater Quality

Due to a lack of data, the picture of groundwater quality across the watershed is not easily defined.
South Nation Conservation has initiated plans to acquire additional data to improve our understanding of the state of our groundwater.  

Sourced from The State of the Nation 2006 published by South Nation Conservation