Middle Rideau Subwatershed Report 2015
DALES CREEK CATCHMENT
The RVCA produces individual reports for ten catchments in the Middle Rideau subwatershed. Using data collected and analysed by the RVCA through its watershed monitoring and land cover classification programs, surface water quality conditions are reported for Dales Creek along with a summary of environmental conditions for the surrounding countryside every six years.
This information is used to better understand the effects of human activity on our water resources, allows us to better track environmental change over time and helps focus watershed management actions where they are needed the most to help sustain the ecosystem services (cultural, aesthetic and recreational values; provisioning of food, fuel and clean water; regulation of erosion/natural hazard protection and water purification; supporting nutrient/water cycling and habitat provision) provided by the catchment’s lands and forests and waters (Millennium Ecosystem Assessment 2005).
The following pages of this report are a compilation of that work and contain information on surface water quality, riparian conditions, land cover, stewardship activity and hazard land and water resources protection.
1. Catchment Facts
- 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
- 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
- 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
- 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)
- 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
- 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
2. Surface Water Quality Conditions
Surface water quality conditions in the Dales Creek catchment are monitored by the Rideau Valley Conservation Authority’s (RVCA) Baseline Water Quality Monitoring Program. The Baseline Water Quality Program focuses on streams; data is collected for 22 parameters including nutrients (total phosphorus, total Kjeldahl nitrogen and ammonia), E. coli, metals (like aluminum and copper) and additional chemical/physical parameters (such as alkalinity, chlorides, pH and total suspended solids). Figure 1 shows the location of the monitoring site in the catchment.
Figure 1 Water quality monitoring site on Dales Creek
Dales Creek Water Quality
Water Quality Rating
The water quality ratings for the Dales Creek catchment is “Fair” (Table 1) as determined by the Canadian Council of Ministers of the Environment (CCME) Water Quality Index and is largely influenced by high nutrient concentrations, metals and high bacterial counts. A "Fair" rating indicates that water quality is usually protected but is occasionally threatened or impaired; conditions sometimes depart from natural or desirable levels. Each parameter is evaluated against established guidelines to determine water quality conditions. Those parameters that frequently exceed guidelines are presented below. Analysis of the data has been broken into two periods; 2003 to 2008 and 2009 to 2014 for the stream monitoring site located on Dales Creek (DAL-01) to examine if conditions have changed between these periods. Table 1 shows the overall rating for the monitored surface water quality site within the Dales Creek catchment and Table 2 outlines the Water Quality Index (WQI) scores and their corresponding ratings.
Water Quality Index Ratings for the Dales Creel catchment
|Sampling Site||Location ||2003-2008||Rating |
|DAL-01||Dales Creek at County Rd. 23||72||Fair|
|Sampling Site||Location ||2009-2014||Rating |
|DAL-01||Dales Creek at County Rd. 23||78||Fair|Table 2
WQI ratings and corresponding index scores (RVCA terminology, original WQI category names in brackets)
|Very Good (Excellent)||95-100|
|Very Poor (Poor)||0-44|
Total phosphorus (TP) is used as a primary indicator of excessive nutrient loading and may contribute to abundant aquatic vegetation growth and depleted dissolved oxygen levels. The Provincial Water Quality Objective (PWQO) is used as the TP Guideline and states that in streams concentrations greater than 0.030 mg/l indicate an excessive amount of TP.
Total Kjeldahl nitrogen (TKN) and ammonia (NH3) are used as secondary indicators of nutrient loadings. RVCA uses a guideline of 0.500 mg/l to assess TKN and the PWQO of 0.020 mg/l to assess NH3 concentrations in Dales Creek.
Tables 3, 4 and 5 summarize average nutrient concentrations at monitored sites within the Creek catchment and show the proportion of results that meet the guidelines.
Summary of total phosphorus results for Dales Creek, 2003-2008 and 2009-2014. Highlighted values indicate average concentrations exceed the guideline
|Total Phosphorous 2003-2008|
|Site||Average||Below Guideline||No. Samples|
|Total Phosphorous 2009-2014|
|Site||Average||Below Guideline||No. Samples|
Summary of total Kjeldahl Nitrogen results for Dales Creek, 2003-2008 and 2009-2014. Highlighted values indicate average concentrations exceed the guideline
|Total Kjeldahl Nitrogen 2003-2008|
|Site||Average||Below Guideline||No. Samples|
|Total Kjeldahl Nitrogen 2009-2014|
|Site||Average||Below Guideline||No. Samples|
Summary of Ammonia results for Dales Creek, 2003-2008 and 2009-2014
|Site||Average||Below Guideline||No. Samples|
|Site||Average||Below Guideline||No. Samples|
Elevated TP results were an occasional occurrence in the 2003-2008 and 2009-2014 monitoring periods at site DAL-01. The 2009-2014 monitoring period saw a marginal improvement with less exceedances. Site DAL-01 had 83 percent of samples that were below the guideline in the 2003-2008 period (Figure 2); this increased to 89 percent of samples in the 2009-2014 period (Figure 3). The average TP concentration for both reporting periods were below the PWQO which slightly decreased from 0.021 mg/l to 0.020 mg/l (Table 3).
Figure 2 Total Phosphorous concentrations in Dales Creek, 2003-2008
Figure 3 Total phosphorous concentrations in Dales Creek, 2009-2014
TKN concentrations show that the bulk of results exceeded the guideline (Figures 4 and 5); there were few samples (15 percent) below the guideline in the 2003-2008 period and this slightly increased to 19 percent in the 2009-2014 period. The average concentration was generally elevated and increased from 0.663 mg/l to 0.737 mg/l (Table 8).
Figure 4 Total Kjeldahl nitrogen concentrations in Dales Creek, 2003-2008
Figure 5 Total Kjeldahl nitrogen concentrations in Dales Creek, 2009-2014
Occasional elevated nutrients were observed in NH3 data. The proportion of results that were below the guideline were 82 percent in 2003-2008 (Figure 6); this decreased to 75 percent in the 2009-2014 reporting periods (Figure 7). The average NH3 concentration slightly increased from 0.007 mg/l to 0.008 mg/l (Table 5).
Figure 6 Ammonia concentrations in Dales Creek, 2003-2008
Figure 7 Ammonia concentrations in Dales Creek, 2009-2014
The data shows that nutrient enrichment is a feature of Dales Creek. Total phosphorous and NH3 occasionally exceed the guidelines while TKN concentrations frequently exceeded the guideline. Elevated TKN concentrations may be influenced by organic matter held by wetland areas found upstream in the Middle Rideau Subwatershed, resulting in naturally high concentrations of organic nitrogen. High nutrient concentrations can help stimulate the growth of algae blooms and other aquatic vegetation in a waterbody and deplete oxygen levels as the vegetation dies off. It is important to reduce human impacts wherever possible. Strategies to reduce nutrient inputs may include diversion of runoff to the creek and enhanced shoreline buffers.
E. coli is used as an indicator of bacterial pollution from human or animal waste; in elevated concentrations it can pose a risk to human health. The PWQO of 100 colony forming units/100 millilitres (CFU/100 ml) is used. E. coli counts greater than this guideline indicate that bacterial contamination may be a problem within a waterbody.
Table 6 summarizes the geometric mean for the monitored site on Dales Creek and shows the proportion of samples that meet the E. coli guideline of 100 CFU/100 ml. The results of the geometric mean with respect to the guideline for the two periods, 2003-2008 and 2009- 2014, are shown in Figures 8 and 9 respectively.
Summary of E. coli results for Dales Creek, 2003-2008 and 2009-2014
|Site||Geometric Mean (CFU/100ml)||Below Guideline||No. Samples|
|Site||Geometric Mean (CFU/100ml)||Below Guideline||No. Samples|
E. coli results at site DAL-01 indicate bacterial counts are occasionally above the E. coli guideline. The proportion of samples below the guideline increased from 34 percent (Figure 8) to 51 percent (Figure 9). E.coli counts decreased slightly between the two monitoring periods (2003-2008 and 2009-2014) with a geometric mean of 81 CFU/100ml to 79 CFU/100ml (Table 6).
Figure 8 Geometric mean of E.coli counts in Dales Creek, 2003-2008
Figure 9 Geometric mean of E.coli counts in Dales Creek, 2009-2014
This data shows that E.coli results occasionally exceed the guidelines at site DAL-01 in Dales Creek. The geometric mean is below the PWQO for both monitoring periods and there has been a decrease in E.coli counts between 2003-2008 and 2009-2014. Properly maintaining septic systems, enhancing shoreline buffers and restricting cattle access can help to improve E.coli levels in Dales Creek.
Of the metals routinely monitored in Dales Creek, aluminum (Al), iron (Fe) and copper (Cu) occasionally reported concentrations above their respective PWQOs. In elevated concentrations, these metals can have toxic effects on sensitive aquatic species.
Tables 7, 8 and 9 summarize metal concentrations at site DAL-01 and show the proportion of samples that meet guidelines. Figures 10 to 15 show metal concentrations with respect to the guidelines for the two periods of interest, 2003–2008 and 2009–2014. For Al, the PWQO is 0.075 mg/l, Cu it is 0.005 mg/l and Fe it is 0.300 mg/l.
Summary of Aluminum results for Dales Creek from 2003-2008 and 2009-2014
|Site||Average (mg/l)||Below Guideline||No. Samples|
|Site||Average (mg/l)||Below Guideline||No. Samples|
Summary of Copper results for Dales Creek from 2003-2008 and 2009-2014
|Site||Average (mg/l)||Below Guideline||No. Samples|
|Site||Average (mg/l)||Below Guideline||No. Samples|
Summary of Iron results for Dales Creek from 2003-2008 and 2009-2014
|Site||Average (mg/l)||Below Guideline||No. Samples|
|Site||Average (mg/l)||Below Guideline||No. Samples|
Results from DAL-01 show that Al concentrations had few exceedances with 85 percent of samples below the guideline in the 2003-2008 period (Figure 10). This improved to 100 percent of samples in the 2009-2014 period (Figure 11). The average concentration of Al was 0.046 mg/l from 2003-2008 and 0.010 mg/l from 2009-2014 which are both below the guideline.
Figure 10 Average aluminum concentrations in Dales Creek, 2003-2008
Figure 11 Average aluminum concentrations in Dales Creek, 2009-2014
Copper concentrations occasionally exceeded the PWQO, with 89 percent of samples below the guideline in 2003-2008 (Figure 12). This decreased to 84 percent of samples being below the guideline in 2009-2014 (Figure 13). The average concentration of Cu was 0.002 mg/l for both reporting periods (Table 8).
Figure 12 Average copper concentrations in Dales Creek, 2003-2008
Figure 13 Average copper concentrations in Dales Creek, 2009-2014
Iron concentrations also surpassed the PWQO guideline. The proportion of samples below the guideline increased from 89 percent to 96 percent (Figures 14 and 15). Although there were observed exceedances, the average concentration did not exceed the guideline in both monitoring periods; 0.225 mg/l in 2003-2008 and .071 mg/l in 2009-2014.
Figure 14 Average iron concentrations in Dales Creek, 2003-2008
Figure 15 Average iron concentrations in Dales Creek, 2009-2014
Overall, a general decline in metal concentrations was observed between the two periods of interest, with the exception of copper which slightly increased. Efforts should continue to be made to identify pollution sources and implement best management practices to reduce any inputs such as runoff, metal alloys, fungicides and pesticides to improve overall stream health and lessen downstream impacts.
 No Ontario guideline for TKN is presently available; however, waters not influenced by excessive organic inputs typically range from 0.100 to 0.500 mg/l, Environment Canada (1979) Water Quality Sourcebook, A Guide to Water Quality Parameters, Inland Waters Directorate, Water Quality Branch, Ottawa, Canada
 A type of mean or average, which indicates the central tendency or typical value of a set of numbers by using the product of their values (as opposed to the arithmetic mean which uses their sum). It is often used to summarize a variable that varies over several orders of magnitude, such as E. coli counts.
3. Riparian Conditions
Shoreline Buffer Land Cover Evaluation
The riparian or shoreline zone is that special area where the land meets the water. Well-vegetated shorelines are critically important in protecting water quality and creating healthy aquatic habitats, lakes and rivers. Natural shorelines intercept sediments and contaminants that could impact water quality conditions and harm fish habitat in streams. Well established buffers protect the banks against erosion, improve habitat for fish by shading and cooling the water and provide protection for birds and other wildlife that feed and rear young near water. A recommended target (from Environment Canada’s Guideline: How Much Habitat is Enough?) is to maintain a minimum 30 meter wide vegetated buffer along at least 75 percent of the length of both sides of rivers, creeks and streams.
Figure 16 shows the extent of the naturally vegetated riparian zone along a 30 metre strip of the shoreline of Dales Creek and its tributaries. This information is derived from a dataset developed by the RVCA’s Land Cover Classification Program through heads-up digitization of 20cm DRAPE ortho-imagery at a 1:4000 scale, which details the catchment landscape using 10 land cover classes.
Figure 16 Natural and other riparian land cover in the Dales Creek catchment
This analysis shows that the riparian buffer in the Dales Creek catchment is comprised of wetland (72 percent), woodland (13 percent), crop and pastureland (12 percent), roads (two percent) and settlement areas (one percent). Additional statistics for the Dales Creek catchment are presented in Table 10 and show that there has been very little change in shoreline cover from 2008 to 2014.
Riparian land cover (2008 vs. 2014) in the Dales Creek catchment
|Riparian Land Cover||2008||2014||Change - 2008 to 2014|
|Crop & Pasture||34||12||33||12||-1||0|
Dales Creek Overbank Zone
Riparian Buffer Width Evaluation
Figure 17 demonstrates the buffer conditions of the left and right banks separately. Dales Creek had a buffer of greater than 30 meters along 95 percent of the right bank and 89 percent of the left bank (Figure 17).
Figure 17 Riparian Buffer Evaluation along Dales Creek
Adjacent Land Use
The RVCA’s Stream Characterization Program identifies seven different land uses beside Dales Creek (Figure 18). Surrounding land use is considered from the beginning to end of the survey section (100m) and up to 100m on each side of the creek. Land use outside of this area is not considered for the surveys but is nonetheless part of the subwatershed and will influence the creek. Natural areas made up 96 percent of the stream, characterized by wetlands, forest, scrubland and meadow. The remaining land use consisted of pasture, residential and infrastructure in the form of road crossings.
Figure 18 Land Use along Dales Creek
Dales Creek Shoreline Zone
Erosion is a normal, important stream process and may not affect actual bank stability; however, excessive erosion and deposition of sediment within a stream can have a detrimental effect on important fish and wildlife habitat. Poor bank stability can greatly contribute to the amount of sediment carried in a waterbody as well as loss of bank vegetation due to bank failure, resulting in trees falling into the stream and the potential to impact instream migration. Figure 19 shows low levels of erosion are dominant along Dales Creek.
Figure 19 Erosion along Dales Creek
Undercut Stream Banks
Undercut banks are a normal and natural part of stream function and can provide excellent refuge areas for fish. Figure 20 shows that Dales Creek was dominated by low levels of undercut banks with an area in the middle reach having high levels of undercut banks.
Figure 20 Undercut stream banks along Dales Creek
Grasses, shrubs and trees all contribute towards shading a stream. Shade is important in moderating stream temperature, contributing to food supply and helping with nutrient reduction within a stream. Figure 21 shows highly variable stream shading conditions ranging from low levels to high levels along Dales Creek.
Figure 21 Stream shading along Dales Creek
Instream Woody Debris
Figure 22 shows that the majority of Dales Creek had low to moderate levels of instream woody debris in the form of branches and trees. Instream woody debris is important for fish and benthic invertebrate habitat, by providing refuge and feeding areas.
Figure 22 Instream woody debris along Dales Creek
Overhanging Trees and Branches
Figure 23 shows low to moderate levels of overhanging branches and trees along Dales Creek. Overhanging branches and trees provide a food source, nutrients and shade which helps to moderate instream water temperatures.
Figure 23 Overhanging trees and branches along Dales Creek
Figure 24 shows 81 percent of Dales Creek remains “unaltered” with no anthropogenic alterations. Nineteen percent of Dales Creek was classified as natural with minor anthropogenic changes in the form of road crossings.
Figure 24 Anthropogenic alterations along Dales Creek
Instream Aquatic Habitat
Freshwater benthic invertebrates are animals without backbones that live on the stream bottom and include crustaceans such as crayfish, molluscs and immature forms of aquatic insects. Benthos represent an extremely diverse group of aquatic animals and exhibit wide ranges of responses to stressors such as organic pollutants, sediments and toxicants, which allows scientists to use them as bioindicators. As part of the Ontario Benthic Biomonitoring Network (OBBN), the RVCA has been collecting benthic invertebrates at the Haskins Road site on Dales Creek since 2003. Monitoring data is analyzed for each sample site and the results are presented using the Family Biotic Index, Family Richness and percent Ephemeroptera, Plecoptera and Trichoptera.
The Hilsenhoff Family Biotic Index (FBI) is an indicator of organic and nutrient pollution and provides an estimate of water quality conditions for each site using established pollution tolerance values for benthic invertebrates. FBI results for Dales Creek are separated by reporting period 2003 to 2008 and 2009 to 2014. “Poor” to “Excellent” water quality conditions being observed at the Dales Creek sample location for the period from 2003 to 2014 (Fig.25) using a grading scheme developed by Conservation Authorities in Ontario for benthic invertebrates.
Figure 25 Hilsenhoff Family Biotic Index on Dales Creek
Family Richness measures the health of the community through its diversity and increases with increasing habitat diversity suitability and healthy water quality conditions. Family Richness is equivalent to the total number of benthic invertebrate families found within a sample. Dales Creek is reported to have “Fair” to “Good” family richness (Fig.26).
Figure 26 Family Richness in Dales Creek
Ephemeroptera (Mayflies), Plecoptera (Stoneflies), and Trichoptera (Caddisflies) are species considered to be very sensitive to poor water quality conditions. High abundance of these organisms is generally an indication of good water quality conditions at a sample location. During certain sampling years the community structure has a relatively high number of species that are sensitive to poor water quality conditions. As a result, the EPT indicates that Dales Creek is reported to have “Poor” to “Good” water quality (Fig.27) from 2003 to 2014.
Figure 27 EPT in Dales Creek
Overall Dales Creek aquatic habitat conditions from a benthic invertebrate perspective are highly variable ranging from “Poor” to “Good” from 2003 to 2014.
Streams are naturally meandering systems and move over time; there are varying degrees of habitat complexity, depending on the creek. Examples of habitat complexity include variable habitat types such as pools and riffles as well as substrate variability and woody debris structure. A high percentage of habitat complexity (heterogeneity) typically increases the biodiversity of aquatic organisms within a system. One hundred percent of Dales Creek was considered heterogeneous, as shown in Figure 28.
Figure 28 Habitat complexity along Dales Creek
Diverse substrate is important for fish and benthic invertebrate habitat because some species have specific substrate requirements and for example will only reproduce on certain types of substrate. Figure 29 shows that 29 percent of the substrate observed on Dales Creek was dominated by bedrock. Overall substrate conditions were highly variable along Dales Creek. Figure 30 shows the dominant substrate type observed for each section surveyed along Dales Creek.
Figure 29 Instream substrate along Dales Creek
Figure 30 shows the dominant substrate type along Dales Creek.
Cobble and Boulder Habitat
Boulders create instream cover and back eddies for large fish to hide and/or rest out of the current. Cobble provides important spawning habitat for certain fish species like walleye and various shiner species who are an important food source for larger fish. Cobble can also provide habitat conditions for benthic invertebrates that are a key food source for many fish and wildlife species. Figure 31 shows where cobble and boulder substrate are found in Dales Creek.
Figure 31 Instream substrate cobble and boulder along Dales Creek
Pools and riffles are important habitat features for fish. Riffles are areas of agitated water and they contribute higher dissolved oxygen to the stream and act as spawning substrate for some species of fish, such as walleye. Pools provide shelter for fish and can be refuge pools in the summer if water levels drop and water temperature in the creek increases. Pools also provide important over wintering areas for fish. Runs are usually moderately shallow, with unagitated surfaces of water and areas where the thalweg (deepest part of the channel) is in the center of the channel. Figure 32 shows that Dales Creek is highly variable; 64 percent consists of runs, 22 percent riffles and 15 percent pools. Figure 33 shows where riffle habitat was observed along Dales Creek.
Figure 32 Instream morphology along Dales Creek
Figure 33 Riffle habitat locations along Dales Creek
Instream vegetation provides a variety of functions and is a critical component of the aquatic ecosystem. For example emergent plants along the shoreline can provide shoreline protection from wave action and important rearing habitat for species of waterfowl. Submerged plants provide habitat for fish to find shelter from predator fish while they feed. Floating plants such as water lilies shade the water and can keep temperatures cool while reducing algae growth. The dominant vegetation type recorded at thirty six percent consisted of algae. Dales Creek had high levels of diversity for instream vegetation. Figure 34 depicts the plant community structure for Dales Creek. Figure 35 shows the dominant vegetation type observed for each section surveyed along Dales Creek.
Figure 34 Vegetation type along Dales Creek
Figure 35 Dominant vegetation type along Dales Creek
Instream Vegetation Abundance
Instream vegetation is an important factor for a healthy stream ecosystem. Vegetation helps to remove contaminants from the water, contributes oxygen to the stream, and provides habitat for fish and wildlife. Too much vegetation can also be detrimental. Figure 36 demonstrates that Dales Creek had common and normal low levels of instream vegetation for only 34 percent of its length. Low, rare and no vegetation was dominate for a total of 65 percent of stream sections. Part of the reason for low levels of vegetation could be due to a high percentage of the stream bottom consisting of bedrock which does not allow aquatic vegetation to become established.
Figure 36 Instream vegetation abundance along Dales Creek
Invasive species can have major implications on streams and species diversity. Invasive species are one of the largest threats to ecosystems throughout Ontario and can out compete native species, having negative effects on local wildlife, fish and plant populations. One hundred percent of the sections surveyed along Dales Creek had invasive species (Figure 37). The invasive species observed in Dales Creek were European frogbit, purple loosestrife, glossy and common buckthorn, curly leafed pondweed, flowering rush, Eurasian milfoil and Manitoba maple. Figure 38 shows the frequency of the invasive species observed along Dales Creek.
Figure 37 Invasive species along Dales Creek
Figure 38 Frequency of Invasive species along Dales Creek
During the stream characterization survey, a YSI probe is used to collect water chemistry information. Dissolved oxygen, conductivity and pH are measured at the start and end of each section.
Dissolved oxygen is a measure of the amount of oxygen dissolved in water. The Canadian Environmental Quality Guidelines of the Canadian Council of Ministers of the Environment (CCME) suggest that for the protection of aquatic life the lowest acceptable dissolved oxygen concentration should be 6 mg/L for warmwater biota and 9.5 mg/L for coldwater biota (CCME, 1999). Figure 39 shows that the dissolved oxygen in Dales Creek was within the threshold for warmwater biota in most reaches of the system, however areas in the headwaters were below the warmwater threshold. The average dissolved oxygen levels observed within the main stem of Dales Creek was 6. 29mg/L which is within the recommended levels for warmwater biota.
Figure 39 Dissolved oxygen ranges in Dales Creek
Conductivity in streams is primarily influenced by the geology of the surrounding environment, but can vary drastically as a function of surface water runoff. Currently there are no CCME guideline standards for stream conductivity; however readings which are outside the normal range observed within the system are often an indication of unmitigated discharge and/or stormwater input. The average conductivity observed within the main stem of Dales Creek was 354 µs/cm. Figure 40 shows the conductivity readings for Dales Creek.
Figure 40 Specific conductivity ranges in Dales Creek
Based on the PWQO for pH, a range of 6.5 to 8.5 should be maintained for the protection of aquatic life. Average pH values for Dales Creek averaged 7.95 thereby meeting the provincial standard.
Figure 41 pH ranges in Dales Creek
Many factors can influence fluctuations in stream temperature, including springs, tributaries, precipitation runoff, discharge pipes and stream shading from riparian vegetation. Water temperature is used along with the maximum air temperature (using the Stoneman and Jones method) to classify a watercourse as either warm water, cool water or cold water. Figure 42 shows the locations of the thermal sampling sites along Dales Creek. Analysis of the data collected indicates that Dales Creek is classified as a cool water system with cool to warm water reaches (Figure 43).
Figure 42 Temperature logger locations on Dales Creek
|DA1 - Rideau River Rd||20.7||28.4||COOLWATER||MACRO||2014|
|DA2 - Haskins Rd||23.0||28.4||COOL-WARM||MACRO||2014|
Figure 43 Temperature logger data for two sites on Dales Creek
Each point on the graph represents a temperature that meets the following criteria:
- Sampling dates between July 1st and September 7th
- Sampling date is preceded by two consecutive days above 24.5 °C, with no rain
- Water temperatures are collected at 4pm
- Air temperature is recorded as the max temperature for that day
Groundwater discharge areas can influence stream temperature, contribute nutrients, and provide important stream habitat for fish and other biota. During stream surveys, indicators of groundwater discharge are noted when observed. Indicators include: springs/seeps, watercress, iron staining, significant temperature change and rainbow mineral film. Figure 44 shows areas where one or more of the above groundwater indicators were observed during stream surveys and headwater assessments.
Figure 44 Groundwater indicators observed in the Dales Creek catchment
Headwaters Drainage Features Assessment
The RVCA Stream Characterization program assessed Headwater Drainage Features for the Middle Rideau subwatershed in 2014. This protocol measures zero, first and second order headwater drainage features (HDF). It is a rapid assessment method characterizing the amount of water, sediment transport, and storage capacity within headwater drainage features (HDF). RVCA is working with other Conservation Authorities and the Ministry of Natural Resources and Forestry to implement the protocol with the goal of providing standard datasets to support science development and monitoring of headwater drainage features. An HDF is a depression in the land that conveys surface flow. Additionally, this module provides a means of characterizing the connectivity, form and unique features associated with each HDF (OSAP Protocol, 2013). In 2014 the program sampled 7 sites at road crossings in the Dales Creek catchment area. Figure 45 spring photos of two sample locations in the Dales Creek catchment from 2014.
Figure 45 Locations of the headwater sampling sites in the Dales Creek catchment
Spring photo from a headwater sample site in the Dales Creek catchment on Scotch Line road west
Summer photo from a headwater sample site in the Dales Creek catchment on Scotch Line road west
The headwater sampling protocol assesses the feature type in order to understand the function of each feature. The evaluation includes the following classifications: defined natural channel, channelized or constrained, multi-thread, no defined feature, tiled, wetland, swale, roadside ditch and pond outlet. By assessing the values associated with the headwater drainage features in the catchment area we can understand the ecosystem services that they provide to the watershed in the form of hydrology, sediment transport, and aquatic and terrestrial functions. The Dales Creek catchment is dominated by natural channel and wetland headwater drainage features. One feature was classified as having been channelized. Figure 46 shows the feature type of the primary feature at the sampling locations.
Figure 46 Headwater feature types in the Dales Creek catchment
Headwater Feature Flow
The observed flow condition within headwater drainage features can be highly variable depending on timing relative to the spring freshet, recent rainfall, soil moisture, etc. Flow conditions are assessed in the spring and in the summer to determine if features are perennial and flow year round, if they are intermittent and dry up during the summer months or if they are ephemeral systems that do not flow regularly and generally respond to specific rainstorm events or snowmelt. Flow conditions in headwater systems can change from year to year depending on local precipitation patterns. Figure 47 shows the observed flow conditions at the sampling locations in the Dales Creek catchment.
Figure 47 Headwater feature flow conditions in the Dales Creek catchment
Feature Channel Modifications
Channel modifications were assessed at each headwater drainage feature sampling location. Modifications include channelization, dredging, hardening and realignments. The sampling locations for the Dales Creek catchment area were classified as having no channel modifications. Figure 48 shows the channel modifications observed at the sampling locations for Dales Creek.
Figure 48 Headwater feature channel modifications in the Dales Creek catchment
Headwater Feature Vegetation
Headwater feature vegetation evaluates the type of vegetation that is found within the drainage feature. The type of vegetated within the channel influences the aquatic and terrestrial ecosystem values that the feature provides. For some types of headwater features the vegetation within the feature plays a very important role in flow and sediment movement and provides wildlife habitat. The following classifications are evaluated no vegetation, lawn, wetland, meadow, scrubland and forest. The features assessed in the Dales Creek catchment were classified as having wetland or meadow vegetation in the feature. Figure 49. Depicts the dominant vegetation observed at the sampled headwater sites in the Dales Creek catchment.
Figure 49 Headwater feature vegetation types in the Dales Creek catchment
Headwater Feature Riparian Vegetation
Headwater riparian vegetation evaluates the type of vegetation that is found along the adjacent lands of a headwater drainage feature. The type of vegetation within the riparian corridor influences the aquatic and terrestrial ecosystem values that the feature provides to the watershed. The majority of the sample locations in Dales Creek were dominated by natural vegetation in the form of meadow, scrubland, forest and wetland vegetation. Figure 50. Depicts the type of riparian vegetation observed at the sampled headwater sites in the Dales Creek catchment.
Figure 50 Headwater feature riparian vegetation types in the Dales Creek catchment
Headwater Feature Sediment Deposition
Assessing the amount of recent sediment deposited in a channel provides an index of the degree to which the feature could be transporting sediment to downstream reaches (OSAP, 2013). Evidence of excessive sediment deposition might indicate the requirement to follow up with more detailed targeted assessments upstream of the site location to identify potential best management practices to be implemented. Conditions ranged from no deposition observed to a site with substantial deposition recorded. Overall the sites had minimal to moderate levels of sediment deposition. Figure 51. Depicts the degree of sediment deposition observed at the sampled headwater sites in the Dales Creek catchment.
Figure 51 Headwater feature sediment deposition in the Dales Creek catchment
Headwater Feature Upstream Roughness
Feature roughness will provide a measure of the amount of materials within the bankfull channel that could slow down the velocity of water flowing within the headwater feature (OSAP, 2013). Materials on the channel bottom that provide roughness include vegetation, woody debris and boulders/cobble substrates. Roughness can provide benefits in mitigating downstream erosion on the headwater drainage feature and the receiving watercourse by reducing velocities. Roughness also provides important habitat conditions to aquatic organisms. The sample locations in the Dales Creek catchment area had variable roughness conditions ranging from extreme to minimal levels. Figure 52 shows the feature roughness conditions at the sampling locations in the Dales Creek catchment.
Figure 52 Headwater feature roughness in the Dales Creek catchment
The Dales Creek catchment is classified as a mixed community of warm and cool water recreational and baitfish fishery with 24 species observed. Table 11 lists those species observed in the catchment (Source: RVCA). Figure 53 depicts the fish sampling locations along Dales Creek.
Figure 53 Dales Creek fish community
Fish species observed in Dales Creek
|Fish Species||Fish code||Fish Species||Fish code|
|blacknose dace||BnDac||finescale dace||FsDac|
|bluntnose minnow||BnMin||largemouth bass||LmBas|
|brassy minnow||BrMin||minnow hybrids||Hy600|
|brook stickleback||BrSti||mottled sculpin||MoScu|
|brown bullhead||BrBul||northern pearl dace||PeDac|
|carps and minnows||CA_MI||northern redbelly dace||NRDac|
|common shiner||CoShi||tessellated darter||TeDar|
|creek chub||CrChu||white sucker||WhSuc|
|etheostoma sp.||EthSp||yellow perch||YePer|
A mottled sculpin captured on Dales Creek which is a sign of cold water habitat conditions
It is important to know locations of migratory obstructions because these can prevent fish from accessing important spawning and rearing habitat. Migratory obstructions can be natural or manmade, and they can be permanent or seasonal. Figure 54 shows that Dales Creek had several beaver dams at the time of the survey in 2014.
Figure 54 Migratory obstructions along Dales Creek
Figure 55 depicts the location of a riparian restoration opportunity as a result of observations made during the stream survey and headwater drainage feature assessments.
Figure 55 Riparian restoration opportunities along Dales Creek
4. Land Cover
Land cover and any change in coverage that has occurred over a six year period is summarized for the Dales Creek catchment using spatially continuous vector data representing the catchment during the spring of 2008 and 2014. This dataset was developed by the RVCA through heads-up digitization of 20cm DRAPE ortho-imagery at a 1:4000 scale and details the surrounding landscape using 10 land cover classes.
As shown in Table 12, the dominant land cover types in 2008 and 2014 were woodland along with wetland.
Land cover (2008 vs. 2014) in the Dales Creek catchment
| Land Cover||2008||2014||Change - 2008 to 2014|
|Crop & Pasture||753||20||729||19||-24||-1|
* Does not include treed swamps ** Includes treed swamps
From 2008 to 2014, there was an overall change of 64 hectares from one land cover class to another. Change within the Dales Creek catchment is primarily associated with wetland encroaching into woodland and the transitioning of crop and pastureland to woodland and conversion to settlement (see Figure 56 for the location of the major changes).
Figure 56 Dominant land cover change in the Dales Creek catchment (2014)
Table 13 shows the type of land cover change that has taken place between land cover classes/types from 2008 to 2014. Overall, the net area of crop and pasture change (loss) is relatively small at 24 hectares relative to the remaining area of crop and pasture in the catchment (as of 2014). Similarly, the net area of woodland change (loss) is very small at 17 hectares relative to the remaining area of woodland in the catchment (as of 2014).
Land cover change in the Dales Creek catchment (2008 to 2014)
|Land Cover||Change - 2008 to 2014|
|Wooded Area to Unevaluated Wetland||31.1||48.4|
|Crop and Pasture to Wooded Area||19.4||30.2|
|Crop and Pasture to Settlement||5.3||8.4|
|Wooded Area to Crop and Pasture||3.4||5.4|
|Crop and Pasture to Transportation||2.7||4.2|
|Wooded Area to Settlement||1.5||2.4|
|Wooded Area to Transportation||0.6||1.0|
|Unevaluated Wetland to Transportation||0.1||0.1|
In the Environment Canada Guideline (Third Edition) entitled “How Much Habitat Is Enough?” (hereafter referred to as the “Guideline”) the opening narrative under the Forest Habitat Guidelines section states that prior to European settlement, forest was the predominant habitat in the Mixedwood Plains ecozone. The remnants of this once vast forest now exist in a fragmented state in many areas (including the Rideau Valley watershed) with woodland patches of various sizes distributed across the settled landscape along with higher levels of forest cover associated with features such as the Frontenac Axis (within the on-Shield areas of the Rideau Lakes and Tay River subwatersheds). The forest legacy, in terms of the many types of wildlife species found, overall species richness, ecological functions provided and ecosystem complexity is still evident in the patches and regional forest matrices (found in the Middle Rideau subwatershed and elsewhere in the Rideau Valley watershed). These ecological features are in addition to other influences which forests have on water quality and stream hydrology including reducing soil erosion, producing oxygen, storing carbon along with many other ecological services that are essential not only for wildlife but for human well-being.
The Guideline also notes that forests provide a great many habitat niches that are in turn occupied by a great diversity of plant and animal species. They provide food, water and shelter for these species - whether they are breeding and resident locally or using forest cover to help them move across the landscape. This diversity of species includes many that are considered to be species at risk. Furthermore, from a wildlife perspective, there is increasing evidence that the total forest cover in a given area is a major predictor of the persistence and size of bird populations, and it is possible or perhaps likely that this pattern extends to other flora and fauna groups. The overall effect of a decrease in forest cover on birds in fragmented landscapes is that certain species disappear and many of the remaining ones become rare, or fail to reproduce, while species adapted to more open and successional habitats, as well as those that are more tolerant to human-induced disturbances in general, are able to persist and in some cases thrive. Species with specialized-habitat requirements are most likely to be adversely affected. The overall pattern of distribution of forest cover, the shape, area and juxtaposition of remaining forest patches and the quality of forest cover also play major roles in determining how valuable forests will be to wildlife and people alike.
The current science generally supports minimum forest habitat requirements between 30 and 50 percent, with some limited evidence that the upper limit may be even higher, depending on the organism/species phenomenon under investigation or land-use/resource management planning regime being considered/used.
As shown in Figure 57, 47 percent of the Dales Creek catchment contains 1659 hectares of upland forest and 182 hectares of lowland forest (treed swamps) versus the 34 percent of woodland cover in the Middle Rideau subwatershed. This is greater than the 30 percent of forest cover that is identified as the minimum threshold required to sustain forest birds according to the Guideline and which may only support less than one half of potential species richness and marginally healthy aquatic systems. When forest cover drops below 30 percent, forest birds tend to disappear as breeders across the landscape.
Figure 57 Woodland cover and forest interior (2014)
Woodland (Patch) Size
According to the Ministry of Natural Resources’ Natural Heritage Reference Manual (Second Edition), larger woodlands are more likely to contain a greater diversity of plant and animal species and communities than smaller woodlands and have a greater relative importance for mobile animal species such as forest birds.
Bigger forests often provide a different type of habitat. Many forest birds breed far more successfully in larger forests than they do in smaller woodlots and some rely heavily on forest interior conditions. Populations are often healthier in regions with more forest cover and where forest fragments are grouped closely together or connected by corridors of natural habitat. Small forests support small numbers of wildlife. Some species are “area-sensitive” and tend not to inhabit small woodlands, regardless of forest interior conditions. Fragmented habitat also isolates local populations, especially small mammals, amphibians and reptiles with limited mobility. This reduces the healthy mixing of genetic traits that helps populations survive over the long run (Conserving the Forest Interior. Ontario Extension Notes, 2000).
The Environment Canada Guideline also notes that for forest plants that do not disperse broadly or quickly, preservation of some relatively undisturbed large forest patches is needed to sustain them because of their restricted dispersal abilities and specialized habitat requirements and to ensure continued seed or propagation sources for restored or regenerating areas nearby.
The Natural Heritage Reference Manual continues by stating that a larger size also allows woodlands to support more resilient nutrient cycles and food webs and to be big enough to permit different and important successional stages to co-exist. Small, isolated woodlands are more susceptible to the effects of blowdown, drought, disease, insect infestations, and invasions by predators and non-indigenous plants. It is also known that the viability of woodland wildlife depends not only on the characteristics of the woodland in which they reside, but also on the characteristics of the surrounding landscape where the woodland is situated. Additionally, the percentage of forest cover in the surrounding landscape, the presence of ecological barriers such as roads, the ability of various species to cross the matrix surrounding the woodland and the proximity of adjacent habitats interact with woodland size in influencing the species assemblage within a woodland.
In the Dales Creek catchment (in 2014), thirty-seven (41 percent) of the 91 woodland patches are very small, being less than one hectare in size. Another 35 (38 percent) of the woodland patches ranging from one to less than 20 hectares in size tend to be dominated by edge-tolerant bird species. The remaining 19 (21 percent of) woodland patches range between 24 and 321 hectares in size. Fifteen of these patches contain woodland between 20 and 100 hectares and may support a few area-sensitive species and some edge intolerant species, but will be dominated by edge tolerant species.
Conversely, four (four percent) of the 91 woodland patches in the drainage area exceed the 100 plus hectare size needed to support most forest dependent, area sensitive birds and are large enough to support approximately 60 percent of edge-intolerant species. Two patches top 200 hectares, which according to the Environment Canada Guideline will support 80 percent of edge-intolerant forest bird species (including most area sensitive species) that prefer interior forest habitat conditions.
Table 14 presents a comparison of woodland patch size in 2008 and 2014 along with any changes that have occurred over that time. A decrease (of 13 ha) has been observed in the overall woodland patch area between the two reporting periods with most change occurring in the 100 to 200 hectare woodland patch size class range.
Woodland patches in the Dales Creek catchment (2008 and 2014)
|Woodland Patch Size Range (ha)||Woodland* Patches||Patch Change|
|2008||2014||2008 to 2014|
|Count||Percent|| Ha||Percent||Count||Percent|| Ha||Percent||Count||Ha|
|Less than 1 ||34||1||14||39||37||41||16||41||3||2|
|1 to 20||34||11||196||39||35||38||207||38||1||11|
|20 to 50||8||15||277||9||8||9||276||9||0||-1|
|50 to 100||7||28||517||8||7||8||510||8||0||-7|
|100 to 200||2||17||312||3||2||2||295||2||0||-17|
|Greater than 200||2||29||538||2||2||2||537||2||0||-1|
*Includes treed swamps
The forest interior is habitat deep within woodlands. It is a sheltered, secluded environment away from the influence of forest edges and open habitats. Some people call it the “core” or the “heart” of a woodland. The presence of forest interior is a good sign of woodland health, and is directly related to the woodland’s size and shape. Large woodlands with round or square outlines have the greatest amount of forest interior. Small, narrow woodlands may have no forest interior conditions at all. Forest interior habitat is a remnant natural environment, reminiscent of the extensive, continuous forests of the past. This increasingly rare forest habitat is now a refuge for certain forest-dependent wildlife; they simply must have it to survive and thrive in a fragmented forest landscape (Conserving the Forest Interior. Ontario Extension Notes, 2000).
The Natural Heritage Reference Manual states that woodland interior habitat is usually defined as habitat more than 100 metres from the edge of the woodland and provides for relative seclusion from outside influences along with a moister, more sheltered and productive forest habitat for certain area sensitive species. Woodlands with interior habitat have centres that are more clearly buffered against the edge effects of agricultural activities or more harmful urban activities than those without.
In the Dales Creek catchment (in 2014), the 91 woodland patches contain 56 forest interior patches (Figure 57) that occupy 11 percent (423 ha.) of the catchment land area (which is greater than the five percent of interior forest in the Middle Rideau Subwatershed). This is above the ten percent figure referred to in the Environment Canada Guideline that is considered to be the minimum threshold for supporting edge intolerant bird species and other forest dwelling species in the landscape.
Most patches (47) have less than 10 hectares of interior forest, 26 of which have small areas of interior forest habitat less than one hectare in size. The remaining nine patches contain interior forest ranging between 16 and 121 hectares in area.
Between 2008 and 2014, there has been a change in the number of woodland patches containing smaller areas of interior habitat (Table 15). For example, there has been an increase of 19 woodlands containing less than one hectare of interior forest over this period and 12 woodlands with one to 10 hectares of interior habitat.
Woodland interior in the Dales Creek catchment (2008 and 2014)
|Woodland Interior Habitat Size Range (ha)||Woodland Interior||Interior Change|
|2008||2014||2008 to 2014|
|Less than 1 ||7||28||1||1||26||46||6||1||19||5|
|1 to 10||9||36||41||9||21||37||66||16||12||25|
|10 to 30||5||20||109||23||5||9||106||25||0||-3|
|30 to 50||0||0||0||0||2||4||71||17||2||71|
|50 to 100||3||12||182||39||1||2||53||12||-2||-129|
|Greater than 100||1||4||128||28||1||2||121||29||0||-7|
Wetlands are habitats forming the interface between aquatic and terrestrial systems. They are among the most productive and biologically diverse habitats on the planet. By the 1980s, according to the Natural Heritage Reference Manual, 68 percent of the original wetlands south of the Precambrian Shield in Ontario had been lost through encroachment, land clearance, drainage and filling.
Wetlands perform a number of important ecological and hydrological functions and provide an array of social and economic benefits that society values. Maintaining wetland cover in a watershed provides many ecological, economic, hydrological and social benefits that are listed in the Reference Manual and which may include:
- contributing to the stabilization of shorelines and to the reduction of erosion damage through the mitigation of water flow and soil binding by plant roots
- mitigating surface water flow by storing water during periods of peak flow (such as spring snowmelt and heavy rainfall events) and releasing water during periods of low flow (this mitigation of water flow also contributes to a reduction of flood damage)
- contributing to an improved water quality through the trapping of sediments, the removal and/or retention of excess nutrients, the immobilization and/or degradation of contaminants and the removal of bacteria
- providing renewable harvesting of timber, fuel wood, fish, wildlife and wild rice
- contributing to a stable, long-term water supply in areas of groundwater recharge and discharge
- providing a high diversity of habitats that support a wide variety of plants and animals
- acting as “carbon sinks” making a significant contribution to carbon storage
- providing opportunities for recreation, education, research and tourism
Historically, the overall wetland coverage within the Great Lakes basin exceeded 10 percent, but there was significant variability among watersheds and jurisdictions, as stated in the Environment Canada Guideline. In the Rideau Valley Watershed, it has been estimated that pre-settlement wetland cover averaged 35 percent using information provided by Ducks Unlimited Canada (2010) versus the 21 percent of wetland cover existing in 2014 derived from DRAPE imagery analysis.
Using the same dataset, it is estimated that pre-settlement (historic) wetland cover averaged 32 percent in the Middle Rideau subwatershed versus the 27 percent of cover existing in 2014. This decline in wetland cover is not evident in the Dales Creek catchment (as seen in Figure 58) where there has been a very slight increase (of less than one percent) in the area of wetland cover from pre-settlement times to the present (as summarized in Table 16).
Figure 58 Catchment wetland cover
While there has been a reported increase in wetland cover in the Dales Creek catchment from pre-settlement times and wetland cover in 2014 remains above the ecological thresholds cited in the Environment Canada Guideline, a “no net loss” of currently existing wetlands should be employed to maintain critical hydrological and ecological functions and to ensure the continued provision of related recreational and economic benefits provided by these wetland habitats in the catchment for landowners and surrounding communities.
Wetland cover in the Middle Rideau subwatershed and Dales Creek catchment (Historic to 2014)
|Wetland Cover||Pre-settlement||2008||2014||Change - Historic to 2014|
|Area ||Area ||Area ||Area |
|Rideau Valley ||134115||35||---||---||80194||21||-53921||-40|
5. Stewardship and Protection
The RVCA and its partners are working to protect and enhance environmental conditions in the Middle Rideau Subwatershed. Figure 59 shows the location of all stewardship projects completed in the Dales Creek catchment along with sites identified for potential shoreline restoration.
Rural Clean Water Projects
From 2009 to 2014, two well decommissionings were completed for a total project value of $2,260 with $1,900 of that amount funded through grant dollars from the RVCA. No projects were carried out before 2009 in the catchment.
Figure 59 Stewardship and potential restoration locations
Tree Planting Projects
The location of RVCA Tree Planting Program projects is shown in Figure 59. From 2009 to 2014, 24,600 trees were planted at three sites. Prior to 2003, 4,000 trees were planted at one site, resulting in the reforestation of 14 hectares. Total value of all four projects is $99,734 with $31,143 of that amount coming from various fundraising sources. No projects were carried out in the catchment between 2003 and 2008.
Through the RVCA Butternut Recovery Program, an additional 10 butternut trees were planted in the Dales Creek catchment between 2009 and 2014, as part of efforts to introduce healthy seedlings from tolerant butternuts into various locations across Eastern Ontario.
Valley, Stream, Wetland and Hazard Land Regulation
The Dales Creek catchment covers 39 square kilometres with 10.5 square kilometres (or 27 percent) of the drainage area being within the regulation limit of Ontario Regulation 174/06 (Figure 60), giving protection to wetland areas and river or stream valleys that are affected by flooding and erosion hazards.
Wetlands occupy 12.5 sq. km. (or 32 percent) of the catchment. Of these wetlands, 7.1 sq. km (or 57 percent) are designated as provincially significant and included within the RVCA regulation limit. This leaves the remaining 5.4 sq. km (or 43 percent) of wetlands in the catchment outside the regulated area limit.
Of the 46.5 kilometres of stream in the catchment, regulation limit mapping has been plotted along 17.5 kilometers of streams (representing 38 percent of all streams in the catchment). Some of these regulated watercourses (15.5 km or 33 percent of all streams) flow through regulated wetlands; the remaining 2 km (or 11 percent) of regulated streams are located outside of those wetlands. Plotting of the regulation limit on the remaining 29 km (or 62 percent) of streams requires identification of flood and erosion hazards and valley systems.
Within the regulation limit, “development” and “site alteration” require RVCA permission. The “alteration to waterways” provision of Ontario Regulation 174/06 applies to all watercourses.
Figure 60 RVCA regulation limits
Vulnerable Drinking Water Areas
The Dales Creek drainage catchment is considered to have a Highly Vulnerable Aquifer. This means that the nature of the overburden (thin soils, fractured bedrock) does not provide a high level of protection for the underlying groundwater making the aquifer more vulnerable to contaminants released on the surface. The Mississippi-Rideau Source Protection Plan includes policies that focus on the protection of groundwater region-wide due to the fact that most of the region, which encompasses the Mississippi and Rideau watersheds, is considered Highly Vulnerable Aquifer. For detailed maps and policies that have been developed to protect drinking water sources, please go to the Mississippi-Rideau Source Protection Region website at www.mrsourcewater.ca to view the Mississippi-Rideau Source Protection Plan.
Surface water quality along Dales Creek is “Fair” over two reporting periods (2003-2008 and 2009-2014) as determined by surface water chemistry data. Frequent exceedances of total Kjeldahl nitrogen and occasional exceedances of total phosphorous, E.coli, aluminum, copper and iron contributed to the rating
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
- Emerald ash borer poses a significant threat to the ecology of the subwatershed, given the prominence of ash trees along shorelines and in riparian and wetland areas. Many tree stands are predominantly ash and with their anticipated loss, it is unclear what will replace them and the overall effect of their collective demise on the physical and natural functions/values they provide for erosion, water quality and fish and wildlife habitat protection
- The catchment contains 250 ha of unevaluated wetland (occupying six percent of its total area) that provides many important social, hydrological, biological and ecological functions/services. Although not under imminent threat from development activity, they do remain vulnerable to drainage and land clearing activities in the absence of any regulatory and planning controls that would otherwise protect them
- Investigate “Fair” surface water quality rating along Dales Creek and its tributaries
- Implement agricultural and residential best management practices to address the elevated total Kjeldahl nitrogen concentrations and occasional high bacterial counts and metal exceedances on Dales Creek by restricting livestock access to the creek, limiting the use of fertilizers and pesticide applications and improving or maintaining a shoreline buffer
- Continue to offer the suite of water quality improvement projects provided by the Rideau Valley Rural Clean Water Program to landowners
- Continue to protect Dales Creek and its tributaries through implementation of municipal and agency land use planning and development policies and practices
- Continue to promote the Rideau Valley Shoreline Naturalization and Tree Planting Programs to landowners
- RVCA and its partners (Village of Merrickville-Wolford, Municipality of North Grenville) are to continue educating landowners about the value and importance of headwater drainage features, natural shorelines and waterfront property best management practices with respect to shoreline use and development, septic system installation and maintenance and shoreline vegetation retention and enhancement
- Protect the riparian buffer along the shoreline of Dales Creek and other catchment streams (headwaters) during the development approvals process through adherence to and enforcement of municipal land-use policies and zoning standards
- Target shoreline restoration at sites identified in this report (shown as “Other riparian land cover” in Figure 16 and “Potential Riparian/Shoreline Restoration” in Figure 55) and explore other restoration and enhancement opportunities along Dales Creek and its tributaries
- Municipalities and agencies are encouraged to strengthen natural heritage and water resources official plan policies and zoning provisions (water setbacks, frontage and naturalized shorelines and wetland protection) where deemed appropriate
- Collectively work with approval authorities (Village of Merrickville-Wolford, Municipality of North Grenville, Conservation Authority) to consistently implement current land use planning and development policies for water quality and shoreline protection adjacent to Dales Creek and other catchment streams (e.g., a minimum 30 metre development setback from water)
- Explore ways and means to more effectively enforce and implement conditions of land-use planning and development approval to achieve net environmental gains (particularly with respect to rehabilitating or protecting naturally vegetated shorelines and water quality)
- Utilize RVCA subwatershed and catchment reports to help develop/revise official plan policies to protect surface water resources and the natural environment (including woodlands, wetlands and shoreline cover)
- Consider establishing RVCA regulations limits to protect additional wetlands
Full Catchment Report