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1. Catchment Facts



General Geography

  • The Rideau River flows through the heart of the Middle Rideau and is a focal point for residents and visitors to the area. It extends from the outlet of Lower Rideau Lake at Poonamalie (where there is one dam and one lock) to Burritts Rapids (where there is also a dam and lock), at which point it enters the Lower Rideau on its way to Rideau Falls. The Rideau River is also an integral part of the Rideau Canal National Historic Site of Canada and is a significant tourist attraction which draws boaters, cottagers, and campers to the area
  • Smiths Falls, Merrickville and Burritts Rapids are the main urban settlements in the Middle Rideau subwatershed. The Dales Creek catchment is predominantly rural in character with agriculture being the main land use
  • Parks Canada staff manage water levels for recreational purposes along the Rideau Canal/Waterway that flows by the catchment, ensuring 1.5 metres of draft during the navigation season. In this managed system, water levels on the Rideau Canal are manipulated by operation of numerous dams. In the Middle Rideau subwatershed, Parks Canada staff operate 9 dam and lock complexes with 13 locks for a fall of 36.2 metres over 35.6 kilometres. Water levels are maintained as close as possible to set objectives through the May to October navigation season. The levels are lowered through the rest of October and into November and held at the winter levels until the spring freshet in late March or early April naturally increases inflows to the system. To reduce the impact of the higher flows in the spring, the amount of snow water equivalent, forecast rain, ice cover, flows and levels are assessed and the dams in the Middle Rideau reach are operated accordingly to quickly pass as much water as possible. In late April and early May, the dams are gradually closed and water levels are brought up to be ready, once again, for the navigation season

Physical Geography

  • All of Dales Creek Catchment and the rest of the Middle Rideau Subwatershed primarily resides within the Smith Falls Limestone Plain, which in this area, happens to consist of Paleozoic dolostone of the Oxford Formation. The bedrock across the catchment is mainly overlain by a thin veneer of glacial sediment, referred to as ‘drift’ that is generally less than a metre in thickness; the landscape is also dotted with organic soils and some glacial till
  • Seventy-nine percent of the catchment lies within the Village of Merrickville-Wolford and 21 percent within the Municipality of North Grenville
  • Dales Creek catchment drainage area is 39 square kilometres and occupies about five percent of the Middle Rideau subwatershed and one percent of the Rideau Valley watershed

Vulnerable Areas

  • The Assessment Report developed under the Ontario Clean Water Act identifies the upper bedrock aquifer underlying all of the catchment area as a Highly Vulnerable Aquifer, although, where sediments are thicker in a local area, the vulnerability would be less. It also identifies the northern half of the catchment being within the Wellhead Protection Area of the Town of Kemptville municipal wells


  • Land uses in the catchment within the Village of Merrickville-Wolford are Rural and Wetland with some Agriculture and Aggregate Resource; within the Municipality of North Grenville, land uses are Rural and Agriculture with some Provincially Significant Wetland

Conditions at a Glance

Water Quality

  • Surface chemistry water quality rating in Dales Creek is “Fair” over two reporting periods (2003-2008 and 2009-2014). Elevated bacterial counts and nutrient concentrations from inflows of nutrients (from private septic systems, agricultural and residential surface water runoff) are occasionally a feature of Dales Creek. Decreased nutrient and bacterial counts are needed to improve the overall health of the creek
  • Instream (biological) water quality conditions at the Dales Creek sample location range from “Poor” to “Good” from 2003 to 2014 (using a grading scheme developed by Ontario Conservation Authorities in Ontario for benthic invertebrates) with an overall benthic invertebrate water quality rating of “Poor” to “Good” determined for this period

Instream and Riparian

  • Overall instream and riparian condition for the Dales creek catchment as assessed by the stream characterization and headwater drainage feature assessment programs show that Dales Creek and its tributaries are in generally good condition. The majority of the system has low erosion levels, a healthy riparian corridor with good instream diversity of aquatic habitat. An opportunity was identified along one of the headwater drainage features to enhance riparian habitat conditions
  • The Dales Creek catchment has 24 species of recreational and bait fish and is classified as having a warm/cool/cold water thermal guild that supports the Dales Creek/Rideau River fishery
  • In the Dales Creek catchment, the riparian buffer (30 m. wide strip along the shoreline of all lakes and streams) is comprised of wetland (72 percent), woodland (13 percent), crop and pastureland (12 percent), roads (two percent) and settlement areas (one percent)

Land Cover

  • Dominant land cover is woodland (43 percent) and wetland (32 percent) followed by crop and pastureland (19 percent), settlement areas (three percent), roads (two percent) and aggregate (one percent). From 2008 to 2014, there was an overall change of 64 hectares (from one land cover class to another). Within the Dales Creek catchment, change is primarily associated with wetland encroaching into woodland and the transitioning of crop and pastureland to woodland and conversion to settlement
  • Woodland cover in the catchment has decreased by 13 hectares between 2008 and 2014 and interior forest habitat has decreased by 38 hectares
  • Wetland cover has increased by one percent (22 ha) from pre-settlement times to the present and now occupies 32 percent of the catchment area


  • There are approximately 197 in-use water wells with provincial records in this catchment. While most water wells are used for domestic water supply many are used for agricultural activities in this catchment; and several are also used for commercial, industrial, and public water supplies or heating and cooling
  • There are two active bedrock quarry licenses in the catchment and one active Permit to Take Water for dewatering at a local bedrock quarry located along the northern catchment boundary and no active Environmental Compliance Approvals. There is one active sand and gravel pit and several closed pits and a small reserve of material of secondary significance

Catchment Care

  • Six stewardship projects have been completed with assistance from the RVCA’s Rural Clean Water and Tree Planting Programs (see Section 5 of this report for details)
  • Dales Creek surface water quality has been monitored by the RVCA through its Baseline Monitoring Program since 2003. The surface water quality at site DAL-01 is monitored once a month from April to November
  • RVCA has been collecting benthic invertebrates in Dales Creek at the Haskins Road site since 2003
  • RVCA conducted a fish survey along Dales Creek in 2014
  • RVCA completed a stream characterization survey on Dales Creek in 2014, working upstream to the headwaters from the mouth of the creek where it empties into the Rideau River taking measurements and recording observations on instream habitat, bank stability, other attributes and preparing a temperature profile
  • RVCA completed seven headwater drainage feature assessments at road crossings in the Dales Creek catchment in 2014. This protocol measures zero and first order headwater drainage features and is a rapid assessment method characterizing the amount of water, sediment transport, and storage capacity within headwater drainage features
  • 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 Dales Creek catchment
  • The Village of Merrickville-Wolford and Municipality of North Grenville have land use planning policies and zoning provisions - on water setbacks, frontage and naturalized shorelines and wetland protection - and in some instances use site plan control to implement these policies and provisions. Together with RVCA, these municipalities work with landowners on a case by case basis to enable new development while ensuring the scale is suitable on the lot, impacts on neighbours are minimized and development maximizes the watercourse setback
  • Development in and adjacent to the Wolford Bog 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 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