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1.0 Perth Catchment: Facts

1.1 General/Physical Geography

Drainage Area

21.4 square kilometres; occupies 2.7 percent of the Tay River subwatershed; 0.5 percent of the Rideau Valley watershed.


The Perth catchment resides predominantly within the physiographic region known as the Smith Falls Limestone Plain, which is a broad flat poorly drained region underlain by thin soils, dolostone and sandstone. A veneer of glacial drift (glacial till, sand etc.) overlies the bedrock and a number of geologic faults may run through this catchment. 

Municipal Coverage

Drummond/North Elmsley Township: (13.2 km2; 62% of catchment)

Town of Perth (7.9 km2; 37% of catchment)

Tay Valley Township (0.2 km2; 1% of catchment)

Stream Length

All watercourses (including headwater streams): 35.1 km

1.2 Vulnerable Areas

Aquifer Vulnerability

Mississippi-Rideau Source Water Protection program has mapped only one very small part of this catchment as a Significant Groundwater Recharge Areas and all of the catchment as a Highly Vulnerable Aquifer (HVA). There are no Well-Head Protection Areas in the catchment.

Wetland Hydrology

A watershed model developed by the RVCA in 2009 was used to study the hydrologic function of wetlands in the Rideau Valley Watershed, including those found in the Perth catchment.

1.3 Conditions at a Glance


One aggregate license in the Perth catchment.

Fish Community/Thermal Regime

Warm and cool water recreational and baitfish fishery with 27 species observed in the Tay River during 2017.


Headwater Drainage Features

Multiple classifications of headwaters containing wetland, natural and undefined features along with historical modifications in the form of straightening (i.e., channelization).  

Instream/Riparian Habitat

Tay River: Low to high habitat complexity was identified along the Tay River in the catchment. Regions with increased habitat complexity were observed in the upper and middle reaches of the system.  Dissolved oxygen conditions along the system are fairly uniform for both warm and coolwater fish species. 

Land Cover Change (2008 to 2014)
Hectares -7 -4 +10 +1
Land Cover Change - Town of Perth (2008 to 2014)
Hectares -6 -2 -1 +9
Land Cover Type - Perth Catchment (2014)
Percent 32 22 22 12 7 2 1 1
Land Cover Type - Town of Perth (2014)
Percent 37 27 12 9 9 4 2
Shoreline Cover Type (30 m. riparian area; 2014)
Catchment-WidePercentTay River - TownPercentStreams*Percent
Woodland 50 Settlement 36 Wetland 62
Wetland 39 Woodland 23 Crop-Pasture 16
Settlement 4 Wetland 19 Woodland 8
Crop-Pasture 3 Transportation 13 Settlement 6
MeadowThicket 3 Meadow-Thicket 7 Transportation 5
Transportation 1 Crop-Pasture 1 Meadow-Thicket 2
--- --- --- --- Aggregate 1
*Excludes the Tay River

Significant Natural Features

Grants Creek Provincially Significant Wetland

Perth Long Swamp Provincially Significant Wetland

Species at Risk (Elemental Occurrence)
StatusSpecies at Risk
Threatened Bobolink Eastern Meadowlark
Water Quality (WQ) for the Protection of Aquatic Life (2006 to 2017)
Tay River@ Rogers Rd.@ Gore St.@ Craig St. 
WQ Rating Fair to Good Good Fair to Good

Water Wells

Approximately 350 operational, private water wells are to be found in the Perth catchment. Groundwater uses are mainly domestic but also include irrigation, industrial, livestock and commercial water supplies and monitoring wells.

Wetland Cover

Perth Catchment: Wetlands are reported to have covered 57 percent of the Perth catchment prior to European settlement, as compared to 32 percent (or 6.8 square kilometres) of the area in 2014. This represents a 44 percent (or 5.4 square kilometre) loss of historic wetland cover. Sixty-three percent of the remaining wetlands are regulated leaving 37 percent (or 2.5 square kilometers) unregulated.

Town of Perth: Wetlands are reported to have covered 61 percent of the Town of Perth prior to European settlement, as compared to 26 percent (or 3.2 square kilometres) of the area in 2014. This represents a 57 percent (or 4.2 square kilometre) loss of historic wetland cover. Eighty-six percent of the remaining wetlands are regulated leaving 14 percent (or 46 ha.) unregulated.

1.4 Catchment Care

Environmental Management

The Town of Perth has an established interest and commitment to environmental stewardship (including the application of innovative, water resources best management practices) as articulated in its Official Plan (2016 Consolidation) and Strategic Plan (2015). The basic premise for community sustainability is that environmental health is critical to human beings and to the wide diversity of plant and animal species with which we co-exist. The quality of our communities and standard of living depends on the air we breathe and the water that we drink, as well as the quality of the soil in the backyards where we play and in the fields and gardens from which our food is produced. In the coming years, human prosperity will depend on the health of the natural environment and the quality of human managed spaces.

The Town of Perth's vision for development embraces the concept of sustainable development through land use and infrastructure development decisions and operational practices that integrate human needs with the natural and built environment. Land use approvals and infrastructure redevelopment decisions will include sustainable design measures for transportation, infrastructure, waste management, energy systems and will strive for the efficient use of natural resources and preservation of historic, cultural and natural heritage features. The vision intends to be adaptive to innovative design and human activities that support sustainability.

The Town of Perth has completed a number of significant water resources projects to protect the surface water quality of the Tay River, in keeping with its vision for sustainable development and commitment to environmental stewardship, including:

  • enhanced removal of total suspended solids during the treatment of drinking water at the Town's water treatment facility, which meets the provincial standard for water discharged to the Tay River (see Section 6.0 of this report)
  • an intensive wet weather flow reduction program (e.g., sewer repairs/sealing; combined sewer elimination), which has reduced average inflows to the Town's wastewater lagoon system
  • enhanced polishing of sewage waste from the Town's existing wastewater lagoon system using the SAGR system (see Section 6.0 of this report)

Development in, and adjacent to, the Perth Long Swamp and Grants Creek Provincially Significant Wetlands in the catchment are subject to Ontario Regulation 174-06 (entitled “Development, Interference with Wetlands and Alterations to Shorelines and Watercourses”) that protects the hydrologic function of the wetland and also protects landowners and their property from natural hazards (flooding, fluctuating water table, unstable soils) associated with them.

Ten active Permits To Take Water (PTTW) are located in the southwestern part of this catchment along with one other active PTTW in its northern part, all for municipal water supply, golf course irrigation, condo heat pumps,  groundwater remediation, industrial use and aggregate operations.

Several Environmental Compliance Approvals and  Environmental Activity and Sector Registries were sought in this catchment for municipal drinking water systems and sewage works along with construction dewatering.

Environmental Monitoring

Town of Perth actively monitors surface water released to the Tay River as part of the Town's commitment to applying best environmental management practices through the treatment of its drinking water and sanitary/storm sewer discharge.

Chemical surface (in-stream) water quality collection by the RVCA since 2003 (see Section 2.1 of this report).

Fish survey and stream characterization survey by the RVCA on the Tay River in 2017 included taking measurements and recording observations on instream habitat, bank stability, other attributes and preparing a temperature profile (see Section 3 of this report).

Seven drainage feature assessments were conducted by the RVCA in 2017 at road crossings in the catchment. The protocol measures zero, first and second order headwater drainage features and is a rapid assessment method characterizing the amount of water, sediment transport, and storage capacity within headwater drainage features (see Section 3.4 of this report).

Classification of Perth catchment land cover types derived by the RVCA from colour aerial photography that was acquired during the spring of 2008 and 2014 (see Section 4.1 of this report).


Twenty-seven stewardship projects were completed by landowners with assistance from the RVCA (see Section 5 of this report).