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1.0 Port Elmsley Catchment: Facts

1.1 General/Physical Geography

Drainage Area

50.9 square kilometres; occupies 6.4 percent of the Tay River subwatershed; 1.2 percent of the Rideau Valley watershed.


The Port Elmsley catchment resides predominantly within part of 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. A geologic fault may run across this catchment.

Municipal Coverage

Drummond/North Elmsley Township (50.3 km2; 99.0% of catchment)

Town of Perth (0.5 km2; 1% of catchment)

Stream Length

All watercourses (including headwater streams): 66.6 km.

1.2 Vulnerable Areas

The Mississippi-Rideau Source Water Protection program has mapped the southwestern boundary of the catchment as a Significant Groundwater Recharge Area and all of the catchment as a Highly Vulnerable Aquifer. 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 Port Elmsley catchment.

1.3 Conditions at a Glance

Fish Community/Thermal Regime

Warm and cool water recreational and baitfish fishery with 19 species observed in the Tay River during 2017.

Headwater Drainage Features

Classified as wetland and channelized features with historical modifications in the form of straightening.  

Instream/Riparian Habitat

Tay River: Low to high habitat complexity was identified for the Tay River in the catchment. Regions with increased habitat complexity were observed throughout most of the reaches of the system. The Tay River has a healthy diversity of plant types and levels throughout most of the surveyed sections. Dissolved oxygen conditions for the Tay River varied along the system for both warm and coolwater species. 


Land Cover Change (2008 to 2014)
Hectares -20 -12 -3 +12 +23
Land Cover Type (2014)
Percent 47 21 18 6 4 2 2
Shoreline Cover Type (30 m. riparian area; 2014)
CatchmentPercentTay RiverPercentStreams*Percent
Crop-Pasture 42 Wetland 72 Crop-Pasture 55
Wetland 35 Woodland 14 Wetland 22
Woodland 14 Crop-Pasture 6 Woodland 14
Settlement  4 Meadow-Thicket 4 Meadow-Thicket 4
Meadow-Thicket  4 Settlement 4 Settlement 3
Transportation 1 Transportation <1 Transportation 2
*Excludes the Tay River

Significant Natural Features

Tay Marsh Provincially Significant Wetland

Westport-Nelson Provincially Significant Wetland Complex

Species at Risk (Elemental Occurrence)
StatusSpecies at Risk
Threatened    Bobolink Eastern Meadowlark Gray Ratsnake
Special Concern Black Tern Eastern Musk Turtle Snapping Turtle
Water Quality for the Protection of Aquatic Life
Water Quality SourceTay River
Surface Chemistry    Good
Instream Biological Fair


Tay River: B enthic invertebrate samples shift in community composition from species that are sensitive to high organic pollution levels in the fall to more tolerant species in the spring.

Water Wells

Over 300 operational private water wells in the Port Elmsley catchment. Groundwater uses are mainly domestic, but also include many monitoring wells and some commercial, livestock and other water supplies .

Wetland Cover

Wetlands are reported to have covered 45 percent of the Port Elmsley catchment prior to European settlement, as compared to 20 percent (or 10.3 square kilometres) of the area in 2014. This represents a 55 percent (or 12.8 square kilometre) loss of historic wetland cover. Fifty-two percent of the remaining wetlands are regulated leaving 48 percent (or 4.8 square kilometers) unregulated. 

1.4 Catchment Care

Environmental Management

Development along the Tay River (Town of Perth eastern boundary to Port Elmsley) and in, and adjacent to, the Tay Marsh Provincially Significant Wetland and the Westport-Nelson Provincially Significant Wetland Complex in the catchment is subject to Ontario Regulation 174-06 (entitled “Development, Interference with Wetlands and Alterations to Shorelines and Watercourses”) that protects landowners and their property from natural hazards (i.e., flooding, fluctuating water table, unstable soils) along with the hydrologic function of the wetland.

One Environmental Compliance Approval was sought for a municipal waste management site in the catchment.

No Permits To Take Water (PTTW) are active in the catchment .

Environmental Monitoring

Chemical surface (in-stream/lake) water quality collection by the RVCA since 2006 (see Section 2 of this report).

Benthic invertebrate (aquatic insect) surface (in-stream) water quality collection in the Tay River by the RVCA since 2003 (see Section 3.3.1 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).

Nineteen 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 Port Elmsley 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-nine stewardship projects were completed by landowners with assistance from the RVCA (see Section 5 of this report).