Open menu

1.0 Jock River-Ashton Dwyer Hill: Catchment Facts

1.1 General/Physical Geography


  • Beckwith (27 km2; 34% of catchment)
  • Ottawa: (53 km2; 66% of catchment)


  • The Ashton Catchment resides with an extensive physiographic region known as the Smith Falls Limestone Plain. In this catchment, the limestone plain is generally but discontinuously overlain by glacial till, organic soils, sand and localized areas of beach sands and gravels
  • In this catchment, bedrock includes the interbedded limestone and dolostone, sandstone with shale and limestone, dolostone, and some limestone respectively from the Gull River, Rockcliffe, Oxford and Bobcaygeon Formations. In addition, numerous geologic faults may pass through the catchment


  • The ground surface ranges in elevation from approximately 162 masl near Hwy 7 to approximately 100 masl at the catchment’s outlet

Drainage Area

  • 81 square kilometers; occupies 14 percent of the Jock River subwatershed, two percent of the Rideau Valley watershed

Stream Length

  • Jock River and tributaries: 153 km

1.2 Vulnerable Areas

Flood/Erosion Hazard

  • Jock River is subject to a flooding hazard during the regional storm flood (the 100 year flood). Surveys and studies undertaken in accordance with provincial standards have determined that the 100 year flood elevation in the catchment ranges from 124.9 metres above mean sea level at the upper, mapped extent of the regulation limit in Ashton Village to 101.8 metres above mean sea level at the Jock Trail

Aquifer Vulnerability

  • The Mississippi-Rideau Source Protection initiative has mapped scattered parts of this catchment as a significant groundwater recharge areas and all the catchment as Highly Vulnerable Aquifer. Wellhead Protection Areas (WHPA) A and parts of WHPAs B, C and D for the municipal wells in Munster Hamlet, underlie a small part of the catchment near Bleeks Road and also Crawford Side Road

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 Ashton-Dwyer Hill catchment

1.3 Conditions at a Glance

Water Quality

  • Surface chemistry water quality rating on the Jock River in the Ashton-Dwyer Hill catchment declines from “Fair” at the upstream (JR-45) site to “Poor” at the downstream site (JR-20). The scores at both sites are largely influenced by frequent high nutrient concentrations and periods of bacterial pollution (see Figure 2)
  • Instream biological water quality conditions at the Jock River Ashton-Dwyer Hill sample location aquatic habitat conditions from a benthic invertebrate perspective is considered “Poor” from 2011 to 2015 as the samples are dominated by species that are moderately sensitive and tolerant to high organic pollution levels

Instream and Riparian

  • Overall instream and riparian condition for the Jock River-Ashton Dwyer Hill catchment as assessed by the stream characterization and headwater drainage feature assessment programs show that the Jock River and its tributaries are in generally good condition. The majority of the system has low erosion levels and a healthy forested riparian corridor along the Jock River. Instream diversity of aquatic habitat is fairly complex in the lower to middle reaches of the Jock River, while the upper reach is dominated by low habitat complexity and poor dissolved oxygen conditions

Thermal Regime

  • Warm/cool water thermal guild supporting the Jock River/Rideau River fishery

Fish Community

  • Thirty-five species of recreational and bait fish

Shoreline Cover Type (30 m. riparian area; 2014)

  • Wetland (36%)
  • Crop and Pasture (28%)
  • Woodland (18%)
  • Settlement (8%)
  • Transportation (7%)
  • Meadow-Thicket (3%)
  • Aggregate (<1%)

Land Cover Type (2014)

  • Crop and Pasture (39%)
  • Woodland (22%)
  • Wetland (21%)
  • Settlement (9%)
  • Meadow-Thicket (4%)
  • Transportation (3%)
  • Aggregate (<1%)
  • Water (<1%)

Land Cover Change (2008 to 2014)

  • Wetland (-61 ha)
  • Woodland (-34 ha)
  • Meadow-Thicket (-20 ha)
  • Crop and Pasture (-5 ha)
  • Water (0 ha)
  • Aggregate (+9 ha)
  • Settlement (+55 ha)
  • Transportation (+56 ha)

Significant Natural Features

  • Goodwood Provincially Significant Wetland
  • Goodwood Marsh Area of Natural and Scientific Interest
  • Manions Corners Provincially Significant Wetland
  • Prospect Bog Provincially Significant Wetland

Water Wells

  • Several hundred (~ 630) operational private water wells in the catchment. Groundwater uses are mainly domestic but also include livestock watering, commercial uses, groundwater monitoring and testing and municipal and other public water supplies


  • One sand and gravel pit within the catchment. Sand and gravel resources are limited and of tertiary importance

Species at Risk (Elemental Occurrence)

  • Loggerhead Shrike, Spotted Turtle (Endangered)
  • Bobolink, Eastern Meadowlark (Threatened)
  • Eastern Milksnake, Snapping Turtle (Special Concern)

1.4 Catchment Care


  • Eighty-three stewardship projects undertaken (see Section 5)

Environmental Monitoring

  • Chemical surface (in-stream) water quality collection since 2003 (see Section 2)
  • Benthic invertebrate (aquatic insect) surface (in-stream) water quality collection since 2011 (see Section 3.3.1)
  • Fish survey along the Jock River (see Section 3.3.11)
  • Stream characterization survey on the Jock River in 2015, working upstream to the headwaters from its mouth  where it empties into the Rideau River, taking measurements and recording observations on instream habitat, bank stability, other attributes and preparing a temperature profile (see Section 3)
  • Twenty headwater drainage feature assessments in 2015 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)

Environmental Management

  • Development in and adjacent to the Provincially Significant Wetlands in the catchment (Goodwood Marsh, Manions Corners, Prospect Bog) 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
  • Ashton Dam water levels are managed by the RVCA on behalf of the Township of Beckwith and the City of Ottawa
  • Three active Permit To Take Water (PTTW) in the catchment issued for municipal water supply and golf course irrigation
  • Seven Environmental Compliance Approvals in the catchment. These are for municipal or private sewage works; an industrial sewage work; a waste management system and air emissions