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1.0 Grants Creek Catchment: Facts

1.1 General/Physical Geography

Drainage Area

31.1 square kilometres; occupies 3.9 percent of the Tay River subwatershed; 0.7 percent of the Rideau Valley watershed.


The Grants Creek catchment resides within part of the physiographic region known as the Algonquin Highlands. In the Tay River Subwatershed, this ancient and hilly geologic region is made up of such Precambrian rocks as marble, conglomerates, and dark or colour banded granite-like rocks. A large area of younger sandstone is found within the centre of the catchment. Although a veneer of glacial drift (glacial till, sand etc.) overlies most of the bedrock in this catchment, large expanses of glacial till and clay overlie the central part of the catchment. A geologic fault may cut across the northern part of this catchment.

Municipal Coverage

Drummond/North Elmsley Township (1.5 km2; 5.0% of catchment)

Tay Valley Township (28.2 km2; 90.9% of catchment)

Town of Perth (1.2 km2; 4.1% of catchment)

Stream Length

All watercourses (including headwater streams): 63.2 km.

1.2 Vulnerable Areas

Aquifer Vulnerability

The Mississippi-Rideau Source Water Protection program has mapped the central part of this 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 Grants Creek catchment.

1.3 Conditions at a Glance

Fish Community/Thermal Regime

Warm and cool water recreational and baitfish fishery with 28 species observed in Grants Creek during 2016.

Headwater Drainage Features

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

Instream/Riparian Habitat

Grants Creek: Low to high habitat complexity. Areas with increased habitat complexity are observed in the lower and upper reaches of the system within the catchment. The habitat complexity is considered low within the Provincially Significant Wetland along Grants Creek as defined by the criteria above; however, the wetland habitat provides the critical benefits of flood storage, water quality treatment, increased biodiversity and important aquatic and terrestrial habitat.

Land Cover Change (2008 to 2014)
Hectares -23 -9 -1 +1 +2 +32
Land Cover Type (2014)
Percent 44 28 15 8 2 2 1
Shoreline Cover Type (30 m. riparian area; 2014)
CatchmentPercentGrants CreekPercentStreams*Percent
Wetland 34 Wetland 56 Crop-Pasture 40
Crop-Pasture 32 Woodland 27 Wetland 27
Woodland  25 Crop-Pasture 8 Woodland 26
Settlement  5 Settlement 6 Settlement 4
Transportation  2 Transportation 1 Transportation 2
Meadow-Thicket 1 Meadow-Thicket 1 Meadow-Thicket 1
*Excludes Grants Creek

Significant Natural Features

Grants Creek Provincially Significant Wetland

Species at Risk (Elemental Occurrence)
StatusSpecies at Risk
Threatened     Blanding's Turtle Eastern Meadowlark
Special Concern Eastern Musk Turtle ---

Water Quality for the Protection of Aquatic Life

Water Quality SourceGrants Creek
Surface Chemistry    Poor to Very Good
Instream Biological Poor to Fair


Grants Creek: Benthic invertebrate samples are highly variable with species that are sensitive and moderately tolerant to high organic pollution levels.

Water Wells

Approximately 220 operational private water wells in the Grants Creek catchment. Groundwater uses are mainly domestic, but also include livestock, industrial and commercial water supplies.

Wetland Cover

Wetlands are reported to have covered 34 percent of the Grants Creek catchment prior to European settlement, as compared to 16 percent (or 4.9 square kilometres) of the area in 2014. This represents a 54 percent (or 5.7 square kilometre) loss of historic wetland cover. Sixty-six percent of the remaining wetlands are regulated leaving 34 percent (or 1.6 square kilometers) unregulated. 

1.4 Catchment Care

Environmental Management

Development along Grants Creek (Glen Tay Road to the Tay River in the Town of Perth) and in, and adjacent to, the Grants Creek Provincially Significant Wetland 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.

Two Environmental Activity and Sector Registries were sought for a vehicle disposal facility and for an industrial heating system in the catchment.

Three Permits To Take Water (PTTW) are active in the catchment for recreation and golf course water supplies.

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 by the RVCA in Grants Creek since 2005 (see Section 3.3.1 of this report).

Fish survey and stream characterization survey by the RVCA on Grants Creek in 2016 included taking measurements and recording observations on instream habitat, bank stability, other attributes and preparing a temperature profile (see Section 3 of this report).

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

The Mississippi Rideau Septic System Office has conducted 41 voluntary septic system re-inspections on 41 properties along Grants Creek from 2004 to 2017 (see Section 5.4 of this report).


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