South Nation Watershed

• Drainage Area: 3900 km2
• General Direction Flow: Northeast
• Headwaters: North of Brockville
• Confluence: The Ottawa River near the village of Plantagenet
• Towns and Cities: 15 municipalities
• Approximate Population:
• Total Length:175km in length
• Elevation: 85 metres
• Predominant Land Cover:
• Predominant Land Use: 57% agriculture
• Rivers and Tributaries: South Nation, Bear Brook, Scotch, Castor and Payne rivers.
• Original Settlement:
• Percentage Water Source: Roughly 60% of the water in the South Nation River is fed by groundwater sources
• Other: High sediment loads caused by stream bank erosion give the water a natural brownish colour.

South Nation/Nation sudPhosphorus Levels

Point sources of phosphorus in the South Nation River and tributaries include municipal and industrial wastewater treatment discharges. Non-point sources may include runoff from fertilizer application, urban stormwater runoff, and leaching due to poor management of septic systems or storage of manure and stream bank erosion.

Compared to other rivers located on the Canadian Shield and St. Lawrence Great Lakes lowlands the South Nation has one of the highest concentrations of total phosphorus. Additions of phosphorus from point and non-point sources have been associated with algal blooms. Increased algal biomass contributes to reduced light penetration crowding out other submerged vegetation and reducing the available habitat for aquatic animals.

South Nation RiverEastern Ontario’s South Nation Watershed is a highly productive agricultural region of the province. However, in some cases, nutrient and bacterial contamination of the South Nation River and its tributaries has been linked to agricultural activities. Understanding the origins of these pollutants is critical to determining the agricultural management practices required to improve water quality in the watershed.

Water quality in the South Nation Watershed is reduced in many areas, while agricultural and urban
pressures continue to increase. Problems include direct cattle access to creeks and brooks, and manure runoff from fields which can lead to fecal contamination of water resources.

South Nation Watershed

The South Nation River is fed by a number of tributaries including the Bear Brook and Scotch rivers in the north and Castor and Payne rivers further south. The average mean discharge of the South Nation River at Plantagenet is 42.1 m3/sec. The South Nation River shows a common stream flow temporal trend with a high discharge in spring (March and April) and much lower stream flow volume in summer months.

Sourced from the South Nation Conservation: State of the Nation Report

South Nation WatershedHistorically the South Nation watershed has suffered considerable environmental degradation as forests were cleared for lumbering in the early 1800s. The South Nation, Castor, and Bear Brook rivers were used for movement and floatation of timber. As agriculture moved in, in the late 1800s many wetlands were converted for farmland. By the early 1900s the South Nation River was dammed at Casselman in order to produce hydroelectric power.

Today lumbering is still carried out using more sustainable forestry methods. Roughly 57% of the watershed is used for farming. Wetlands and forests are important in maintaining and controlling water levels within the river. As both wetlands and forests have become reduced and degraded within the watershed the South Nation River has become increasingly vulnerable to droughts in summer and flooding in the spring.

Sourced from the South Nation Conservation: State of the Nation Report

Canard Pilet / Northern Pintail ( male )Biodiversity is a term used to describe the variation in genetic diversity, species diversity and ecosystem diversity. Trends in biodiversity provide indications of the condition of the environment as all species are dependent on a healthy ecosystem and habitat for survival. Currently there exist many threats to biodiversity.

South Nation/Nation SudConservation Authorities help Ontario communities to adapt to climate change because of the work they do in our watersheds.

• monitor watershed conditions and participate in developing  integrated watershed management plans;
• map our water & other resources in order to know how much we have, how it’s being used and what is needed to keep the watershed healthy;
• deliver Watershed Stewardship programs that protect water resources in partnership with landowners;
• make sure our flood and erosion plans are up to date and in line with current predicted standards;
• monitor low water levels and encourage water users to conserve.