Jock River Subwatershed Report 2016
MONAHAN DRAIN CATCHMENT
The RVCA produces individual reports for 12 catchments in the Jock River subwatershed. Using data collected and analyzed by the RVCA through its watershed monitoring and land cover classification programs, surface water quality and in-stream conditions are reported for the Jock River 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 sections of this report for the Monahan Drain catchment are a compilation of that work.
|Surface Water Quality Conditions
|Land Stewardship and Water Resources Protection
For other Jock River catchments and the Jock River Subwatershed Report, please visit the RVCA website at www.rvca.ca
Figure 1 Land cover in the Monahan Drain catchment
1.0 Monahan Drain Catchment: Facts
1.1 General/Physical Geography
- Ottawa: (45 km2; 100% of catchment)
- The Monahan Catchment resides within an extensive physiographic region known as the Ottawa Valley Clay Plain. This part of the clay plain can be greater than 15 metres deep but is truncated to the north and west where Paleozoic bedrock outcrops at the ground surface. This sediment was deposited in the Champlain Sea after the last glaciation. In this catchment, the Kars Esker, a regional sand and gravel feature, is found beneath the clay plain and is oriented northwest–southeast
- In this catchment, the clay plain and buried esker are underlain mostly by dolostone and some limestone from the Oxford, Gull River and Bobcaygeon Formations. In addition, several geologic faults may pass through the catchment
- The ground surface ranges in elevation from approximately 125 masl near along Old Richmond Road to approximately 90 masl at the catchment’s outlet
- 45 square kilometers; occupies eight percent of the Jock River subwatershed, one percent of the Rideau Valley watershed
- Monahan Drain and tributaries: 97 km
1.2 Vulnerable Areas
- The Mississippi-Rideau Source Protection initiative has not identified any Significant Groundwater Recharge Areas (SGRA), Highly Vulnerable Aquifers (HVA) or Wellhead Protection Areas (WHPA) in the catchment
- 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 Monahan Drain catchment
1.3 Conditions at a Glance
- Surface chemistry water quality rating in the Monahan Drain catchment is rated as “Poor” at both monitored water quality sites for the 2010-2015 period. The scores are largely influenced by frequent high nutrient concentrations, bacterial pollution, occasional metal exceedances and elevated chloride levels
- Instream biological water quality conditions in the Monahan Drain are unknown
Instream and Riparian
- Overall instream and riparian condition for the Monahan Drain is unknown
- Warm/cool water thermal guild supporting the Jock River fishery
- Twenty-three species of recreational and bait fish
Shoreline Cover Type (30 m. riparian area; 2014)
- Crop and Pasture (65%)
- Settlement (14%)
- Transportation (13%)
- Woodland (6%)
- Meadow-Thicket (2%)
Land Cover Type (2014)
- Crop and Pasture (60%)
- Settlement (22%)
- Transportation (8%)
- Woodland (7%)
- Meadow-Thicket (2%)
- Aggregate (1%)
- Wetland (<1%)
- Water (<1%)
Land Cover Change (2008 to 2014)
- Crop and Pasture (-181 ha)
- Woodland (-36 ha)
- Meadow-Thicket (-4 ha)
- Wetland (0 ha)
- Water (+3 ha)
- Aggregate (+8 ha)
- Transportation (+59 ha)
- Settlement (+152 ha)
Significant Natural Features
- Stony Swamp Provincially Significant Wetland
- Several hundred (~500) operational private water wells in the Monahan Drain Catchment. Groundwater uses are mainly domestic, but also include groundwater monitoring and testing, municipal and other public water supplies, livestock watering and crop irrigation and commercial and industrial uses
- Sections of three bedrock quarry licenses within the catchment
Species at Risk (Elemental Occurrence)
- Bobolink (Threatened)
- Eastern Milksnake (Special Concern)
1.4 Catchment Care
- Twenty-two stewardship projects undertaken (see Section 5)
- Chemical surface (in-stream) water quality collection since 2003 (see Section 2)
- Fish survey along the Monahan Drain (see Section 3.1.3)
- Thirteen 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 3.2)
- Groundwater chemistry information is available from the Ontario Geological Survey for two wells located in this catchment
- Development along the Monahan Drain and in and adjacent to the Stony Swamp 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
- Twenty active Permits To Take Water (PTTW) in the Monahan Drain catchment issued for ongoing construction dewatering and 1 active PTTW for nursery irrigation
- Twenty Environmental Compliance Approvals and/or Environmental Activity and Sector Registrations in the Monahan Drain Catchment. Most of these approvals/registrations are for municipal and private sewage works and municipal drinking water systems, while others are for waste management systems, municipal or private water works, industrial sewage works and air emissions
2.0 Monahan Drain Catchment: Surface Water Quality Conditions
Surface water quality conditions in the Monahan Drain catchment are monitored by the City of Ottawa’s Baseline Water Quality Monitoring Program. This program provides information on the condition of Ottawa’s surface water resources; data is collected for multiple 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). The locations of monitoring sites are shown in Figure 2 and Table 1.
Figure 2 Water quality monitoring sites on the Monahan Drain
2.1 Monahan Drain Water Quality Rating
The RVCA's water quality rating for the Monahan Drain sites (CK68-01 and CK68-03) are “POOR” (Table 1) as determined by the Canadian Council of Ministers of the Environment (CCME) Water Quality Index. A “POOR” rating indicates that water quality is frequently threatened or impaired; conditions often 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. Table 1 shows the overall rating for the monitored surface water quality sites within the Monahan Drain catchment and Table 2 outlines the Water Quality Index (WQI) scores and their corresponding ratings.
There are two monitored water quality sites on the Monahan Drain in this catchment (CK68-01 and CK68-03, Figure 2). There is limited data prior to 2010, therefore only data from the 2010-2015 period will be presented in the following. Water quality scores at both sites is reported as “Poor” (Table 1). The scores at these sites are largely influenced by frequent high nutrient concentrations, bacterial pollution, occasional metal exceedances and elevated chloride levels. For more information on the CCME WQI, please see the Jock River Subwatershed Report.
Water Quality Index ratings for the Monahan Drain Catchment
Water Quality Index ratings and corresponding index scores (RVCA terminology, original WQI category names in brackets)
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 loading. 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 the Jock River.
Tables 3, 4 and 5 summarize average nutrient concentrations at monitored sites within the Jock River-Barrhaven catchment and show the proportion of results that meet the guidelines.
Summary of total phosphorus results for the Monahan Drain catchment, 2004-2009 and 2010-2015. Highlighted values indicate average concentrations exceed the guideline
Summary of total Kjeldahl nitrogen results for the Monahan Drain catchment from 2004-2009 and 2010-2015. Highlighted values indicate average concentrations exceed the guideline
Summary of ammonia results for Monahan Drain catchment from 2004-2009 and 2010-2015. Highlighted values indicate average concentrations exceed the guideline
Monitoring Site CK68-01
The majority of samples at site CK68-01 were above the TP guideline in the 2010-2015 monitoring period. There were no samples below the guideline (Figure 3) and the average concentration was 0.108 mg/l.
TKN concentrations show that the bulk of results exceeded the guideline (Figure 4); there were few samples (two percent) in the 2010-2015 period. The average concentration was elevated at 0.851 mg/l (Table 4).
In the 2010-2015 reporting period only 10 percent of NH3 results were below the guideline with an average concentration of 0.227 mg/l (Figure 5, Table 5).
Monitoring Site CK68-03
Elevated TP results were also common occurrence at site CK68-03. There were no TP results below the guideline in the 2010-2015 period (Figure 3). The average TP concentration was well above the PWQO guideline at 0.140 mg/l (Table 3).
Similar to TP results, all samples analyzed for TKN have exceeded the guideline (Figure 4). The average concentration was 1.115 mg/l (Table 4).
The results for NH3 indicate that exceedances were common. Twelve percent of samples were below the guideline in the 2010-2015 period (Figure 5). The average NH3 concentration was 0.399 mg/l (Table 5).
Figure 3 Total phosphorous concentrations in the Monahan Drain, 2010-2015
Figure 4 Total Kjeldahl nitrogen concentrations in the Monahan Drain, 2010-2015
Figure 5 Ammonia concentrations in the Monahan Drain, 2010-2015
Nutrient enrichment is a feature in the monitored portions of the Monahan Drain. Overall, average nutrient concentrations are very high with very few results below established guidelines. All parameters (total phosphorus, total Kjeldahl nitrogen and ammonia) are above guidelines at each site. Elevated nutrients may result in nutrient loading to the Jock River. 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. Best management practices such as minimizing storm water runoff, enhanced shoreline buffers, preventing fertilizer runoff and restricting cattle access in upstream agricultural areas can help to reduce nutrient enrichment in the Jock River.
2.3 Escherichia coli
Escherichia coli (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 sites on the Jock River within the Barrhaven catchment 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 is shown in Figure 6.
Summary of E. coli
results for the Jock River, 2010-2015
Monitoring Site CK68-01
E. coli counts at site CK68-01 indicate bacterial pollution at this site is common, the majority of results exceeded the PWQO with 43 percent of samples below the guideline (Figure 6). The count at the geometric mean was 125 CFU/100ml (Table 6).
Monitoring Site CK68-03
Elevated E. coli counts at site CK68-03 were also a regular occurrence. The majority of samples (51 percent) were below the guideline (Figure 6). The geometric mean was just above the PWQO at 101 CFU/100ml (Table 6).
Figure 6 E.coli count in the Monahan Drain, 2010-2015
Bacterial pollution appears to be a significant concern in Monahan Drain. Both sites (CK68-01 and CK68-03) have regular exceedances and counts at the geometric mean are above the guideline of 100 CFU/100ml. Best management practices such as restricting livestock assess and minimizing runoff should be employed wherever possible to protect water quality conditions in this tributary and downstream impacts on the Jock River.
Of the metals routinely monitored in the Monahan Drain, aluminum (Al) regularly reported concentrations above the respective PWQO. In elevated concentrations, these metals can have toxic effects on sensitive aquatic species.
Table 7 summarize metal concentrations at sites CK68-01 and CK68-03, and show the proportion of samples that meet guidelines. Figure 7 shows Al concentration with respect to the guideline of 0.075 mg/l for 2010-2015 period.
Summary of Aluminum results in the Monahan Drain, 2010-2015. Highlighted values indicate average concentrations exceed the guideline
Monitoring Site CK68-01
The average Al concentration at site CK68-01 exceeded the guideline, only 20 percent of result were below the guideline (Figure 7). The average concentration was also elevated at 0.306 mg/l (Table 7).
Monitoring Site CK68-03
Results from site show elevated Al concentrations are also a concern further upstream. Only 34 percent of samples were below the guideline (Figure 7). The average concentration of Al was 0.385 mg/l (Table 7).
Figure 7 Average aluminum concentrations in the Monahan Drain, 2010-2015
In the Monahan Drain catchment aluminum concentrations have increased at both sites, CK68-01 and CK68-03. Increased concentrations appear to be more common during the spring and fall and therefore may be due to increased runoff from rainfall/meltwater. Efforts should continue to be made to identify pollution sources and implement best management practices to reduce any inputs such as storm water runoff, metal alloys from vehicle traffic, fungicides and pesticides to improve overall stream health and lessen downstream impacts.
Chloride is a naturally occurring component of surface water. However, it has been shown to an indicator of increasing urbanization due to runoff from road salt application and can impact sensitive aquatic species. Of all the sites monitored in the Jock River subwatershed the two sites on the Monahan Drain were the only locations that had the majority of samples above the chloride guideline of 120 mg/l.
Summary of chloride results in the Monahan Drain, 2010-2015
Monitoring Site CK68-01
The average chloride concentration at site CK68-01 was below the guideline at 94 mg/l. Though overall the concentration met the objective only 29 percent of result were below the guideline (Figure 8). The average concentration was also elevated at 306 mg/l (Table 8).
Monitoring Site CK68-03
Results from site show elevated chloride concentrations are also a concern further upstream. Only 22 percent of samples were below the guideline (Figure 8). The average concentration was 99 mg/l (Table 7).
Figure 8. Chloride concentrations in the Monahan Drain, 2010-2015
In the Monahan Drain catchment there is evidence of elevated chloride concentrations at both sites, CK68-01 and CK68-03. The concentrations tend to be elevated regardless of the season, (please note the result for January in Figure 8 is based on a single sample value). As this is a highly altered feature in a agricultural area, it is likely to be impacted by local land uses. Further investigation is perhaps warranted to see if the outflow has an impact on the Jock River.
1 The City of Ottawa Baseline Water Quality Monitoring Program has also applied the CCME WQI to monitored sites. The parameters used in the index and time periods differs between the RVCA and City of Ottawa’s application of the index, thus in same cases has resulted in different ratings
2 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
3 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
3.0 Monahan Drain Catchment: Riparian Conditions
3.1 Monahan Drain Instream Aquatic Habitat
3.1.1 Thermal Regime
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 9 shows where the thermal sampling site was located on Monahan Drain. Analysis of the data collected indicates that Monahan Drain is classified as a warm water system (Figure 10).
Figure 9 Temperature logger location in the Monahan Drain catchment on Old Richmond Road
Figure 10 Temperature logger data for the site location on Monahan Drain.
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 11 shows areas where one or more of the above groundwater indicators were observed during the headwater assessments.
Figure 11 Groundwater indicators observed in the Monahan Drain catchment
3.1.3 Fish Community
The Monahan Drain catchment is classified as a mixed community of warm and cool water recreational and baitfish fishery with 23 species observed. Figure 12 shows the sampling locations in the Monahan Drain catchment.
Figure 12 Monahan Drain catchment fish community
The following table contains a list of species observed in the watershed.
Fish species observed in Monahan Drain catchment
3.2 Headwater Drainage Features Assessment
3.2.1 Headwaters Sampling Locations
The RVCA Stream Characterization program assessed Headwater Drainage Features for the Jock River subwatershed in 2015. 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 2015 the program sampled 13 sites at road crossings in the Monahan Drain catchment area (Figure 13).
Figure 13 Locations of the headwater sampling sites in the Monahan Drain catchment
3.2.2 Headwater Feature Type
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. Six features were classified as having been channelized, 3 features were roadside ditches, one wetland which was an online stormwater pond/constructed wetland and two features were identified as natural. Figure 14 shows the feature type of the primary feature at the sampling locations.
Figure 14 Headwater feature types in the Monahan Drain catchment
3.2.3 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 15 shows the observed flow conditions at the sampling locations in the Monahan Drain catchment in 2015.
Figure 15 Headwater feature flow conditions in the Monahan Drain catchment
A spring photo of the headwater sample site in the Monahan Drain catchment located on Fernbank Road
A summer photo of the headwater sample site in the Monahan Drain catchment located on Fernbank Road
3.2.4 Feature Channel Modifications
The majority of the headwater drainage features in the Monahan catchment are classified as municipal drains and have been historically created and or modified natural systems. Channel modifications were assessed at each headwater drainage feature sampling location. Modifications include dredging, channel hardening and mixed modifications. The Monahan Drain catchment area had one feature which was classified as being hardened, seven classified as dredged and four were identified as having mixed modifications. Figure 16 shows the channel modifications observed at the sampling locations for Monahan Drain.
Figure 16 Headwater feature channel modifications in the Monahan Drain catchment
3.2.5 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 fish and wildlife habitat. The following classifications are evaluated no vegetation, lawn, wetland, meadow, scrubland and forest. The features assessed in the Monahan Drain catchment were classified as being dominated by wetland and meadow vegetation. Three features were classified as having no vegetation within the channel. Figure 17 depicts the dominant vegetation observed at the sampled headwater sites in the Monahan Drain catchment.
Figure 17 Headwater feature vegetation types in the Monahan Drain catchment
3.2.6 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. Four sample locations in Monahan Drain were dominated by natural vegetation in the form of scrubland and meadow vegetation. Nine sample locations were dominated by other forms of vegetation of either crops or ornamental grasses. Figure 18 depicts the type of riparian vegetation observed at the sampled headwater sites in the Monahan Drain catchment.
Figure 18 Headwater feature riparian vegetation types in the Monahan Drain catchment
3.2.7 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 extensive deposition recorded. Figure 19 depicts the degree of sediment deposition observed at the sampled headwater sites in the Monahan Drain catchment.
Figure 19 Headwater feature sediment deposition in the Monahan Drain catchment
3.2.8 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 for aquatic organisms. The sample locations in the Monahan Drain catchment area ranged from minimal to extreme roughness conditions. Figure 20 shows the feature roughness conditions at the sampling locations in the Monahan Drain catchment.
Figure 20 Headwater feature roughness in the Monahan Drain catchment
4.0 Monahan Drain Catchment: Land Cover
Land cover and any change in coverage that has occurred over a six year period is summarized for the Monahan Drain 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.
4.1 Monahan Drain Catchment Change
As shown in Table 10 and Figure 1, the dominant land cover type in 2014 was crop and pastureland, followed by settlement.
Land cover (2008 vs. 2014) in the Monahan Drain catchment
* Does not include treed swamps ** Includes treed swamps
From 2008 to 2014, there was an overall change of 307 hectares (from one land cover class to another). Most of the change in the Monahan Drain catchment is a result of the conversion of crop and pastureland and woodland to settlement and transportation (Figure 21).
Figure 21 Land cover change in the Monahan Drain catchment (2014)
Table 11 provides a detailed breakdown of all land cover change that has taken place in the Monahan Drain catchment between 2008 and 2014.
Land cover change in the Monahan Drain catchment (2008 to 2014)
4.2 Woodland Cover
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 Jock River 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 22, seven percent of the Monahan Drain catchment contains 315 hectares of upland forest versus the 26 percent of woodland cover in the Jock River subwatershed. This is less 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 22 Woodland cover and forest interior (2014)
4.2.1 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 Monahan Drain catchment (in 2014), fifty-two (52 percent) of the 100 woodland patches are very small, being less than one hectare in size. Another 45 (45 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 three (three percent of) woodland patches range between 24 and 41 hectares in size and may support a few area-sensitive species along with some edge intolerant species, but will be dominated by edge tolerant species. No patch exceeds the 100 plus hectare size needed to support most forest dependent, area sensitive birds and which are large enough to support approximately 60 percent of edge-intolerant species. No patch tops 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 12 presents a comparison of woodland patch size in 2008 and 2014 along with any changes that have occurred over that time. A decrease (of 37 ha) has been observed in the overall woodland patch area between the two reporting periods with most change occurring in the 20 to50 hectare woodland patch size class range.
Woodland patches in the Monahan Drain catchment (2008 and 2014)
*Includes treed swamps
4.2.2 Woodland (Forest) Interior Habitat
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 Monahan Drain catchment (in 2014), the 100 woodland patches contain 11 forest interior patches (Figure 22) that occupy less than one percent (25 ha.) of the catchment land area (which is less than the three percent of interior forest in the Jock River Subwatershed). This is below 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 (10) have less than 10 hectares of interior forest, six of which have small areas of interior forest habitat less than one hectare in size. The remaining patch contains 15 hectares of interior forest. Between 2008 and 2014, there was an overall loss of nine hectares of interior forest in the catchment (Table 13).
Woodland interior in the Monahan Drain catchment (2008 and 2014)
4.3 Wetland Cover
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 51 percent in the Jock River subwatershed versus the 24 percent of cover existing in 2014 (as summarized in Table 14).
Wetland cover in the Jock River subwatershed and Monahan Drain catchment (Historic to 2014)
This decline in wetland cover is also evident in the Monahan Drain catchment (as seen in Figure 23) where wetland was reported to cover 69 percent of the area prior to settlement, as compared to less than one percent in 2014. This represents a 99 percent loss of historic wetland cover and what remains (in 2014) falls far below the 40 percent historic wetland threshold cited in the Environment Canada Guideline for maintaining key ecological and hydrological functions. To maintain critical hydrological, ecological functions along with related recreational and economic benefits provided by these wetland habitats in the catchment, the Guideline recommends a “no net loss” approach for currently existing wetlands combined with efforts to work towards restoring upwards of 40 percent of the historic wetland coverage, where feasible.
Figure 23 Catchment wetland cover
4.4 Shoreline Cover
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 the Environment Canada Guideline) is to maintain a minimum 30 metre wide vegetated buffer along at least 75 percent of the length of both sides of rivers, creeks and streams.
Figure 24 shows the extent of the ‘Natural’ vegetated riparian zone (predominantly wetland/woodland features) and ‘Other’ anthropogenic cover (crop/pastureland, roads/railways, settlements) along a 30-metre-wide area of land, both sides of the shoreline of the Jock River and its tributaries in the Monahan Drain catchment.
Figure 24 Natural and other riparian land cover in the Monahan Drain catchment
This analysis shows that the riparian buffer in the Monahan Drain catchment in 2014 was comprised of crop and pastureland (65 percent), settlement (14 percent), transportation (13 percent), woodland (six percent), and meadow-thicket (two percent). Additional statistics for the Monahan Drain catchment are presented in Table 15. Of particular interest is the observed increase in the area of “Settlement” along the shoreline of the Monahan Drain over a six year period.
Riparian land cover (2008 vs. 2014) in the Monahan Drain catchment
5.0 Monahan Drain Catchment: Stewardship and Water Resources Protection
The RVCA and its partners are working to protect and enhance environmental conditions in the Jock River Subwatershed. Figure 25 shows the location of all stewardship projects completed in the Monahan Drain catchment along with sites identified for potential shoreline restoration.
5.1 Rural Clean Water Projects
From 2010 to 2015, two clean water diversions, one windbreak buffer, one well decommissioning and one manure storage/wastewater runoff project were completed. Between 2004 and 2009, two septic system replacements, one well decommissioning, one well replacement and one well upgrade were completed. Prior to 2004, five crop residue projects and one livestock fencing were completed. Total value of all 16 projects is $336,954 with $34,463 of that amount funded through grant dollars from the RVCA.
Figure 25 Stewardship site locations
5.2 Private Land Forestry Projects
The location of RVCA tree planting projects is shown in Figure 25. From 2010 to 2015, 13,350 trees were planted at two sites. Between 2004 and 2009, 6000 trees were planted at three sites. No trees were planted in the catchment prior to 2004, In total, 19,350 trees were planted, resulting in the reforestation of 10 hectares. Total value of all five projects is $100,739 with $34,607 of that amount coming from various fundraising sources.
5.3 Shoreline Naturalization Projects
With the assistance of the RVCA’s Shoreline Naturalization Program, 234 trees and shrubs were planted to create a 77 metre long shoreline buffer along the Monahan Drain at a total project value of $4,004.
5.4 Valley, Stream, Wetland and Hazard Lands
The Monahan Drain catchment covers 45 square kilometres with 1 square kilometre (or two percent) of the drainage area being within the regulation limit of Ontario Regulation 174/06 (Figure 26), giving protection to wetland areas and river or stream valleys that are affected by flooding and erosion hazards.
Wetlands occupy 12.5 ha. (or less than one percent) of the catchment, all of which are designated as provincially significant and included within the RVCA regulation limit.
Of the 97.2 kilometres of stream in the catchment, regulation limit mapping has been plotted along 4.2 kilometers of streams (representing four percent of all streams in the catchment). Plotting of the regulation limit on the remaining 93 km (or 96 percent) of streams requires identification of flood and erosion hazards and valley systems.
Within those areas of the Monahan Drain catchment subject to the RVCA regulation (limit), efforts (have been made and) continue through RVCA planning and regulations input and review to manage the impact of development (and other land management practices) in areas where “natural hazards” are associated with rivers, streams, valley lands and wetlands. Additionally, in the rapidly urbanizing areas of Kanata South within the Monahan Drain catchment , significant effort is made through land use planning and development control processes and carefully planned stormwater management systems, initially guided by master drainage planning and integrated subwatershed planning, to meet the natural heritage and natural hazards policies presented in the City of Ottawa Official Plan. Also, within areas beyond the regulation limit, protection of the catchment’s watercourses is provided through the “alteration to waterways” provision of the regulation.
Figure 26 RVCA regulation limits
6. Monahan Drain Catchment: Challenges/Issues
Surface chemistry water quality in the Monahan Drain catchment is “Poor” at both monitored water quality sites for the 2010-2015 period. The scores at these sites are largely influenced by frequent high nutrient concentrations, bacterial pollution, occasional metal exceedances and elevated chloride levels
Instream biological water quality conditions in the Monahan Drain are unknown
Natural hazard lands have not been identified
Effect of climate change on the hydrologic function of the Jock River subwatershed and associated natural hazards (flood risk) posed to the built/urban areas of the catchment are not fully understood
Existing hydrological and geochemical datasets and assessments (academic, RVCA, others) are only recently available and/or are not being considered in the characterization of the numerous hydrologic functions of the Jock River subwatershed. Further, there is a dearth of hydrologic information (hydroperiod, groundwater/surface water interactions, geochemistry) about the wetlands that remain in the Jock River subwatershed
‘Natural’ vegetation covers eight percent of the riparian zone of Monahan Drain and its tributaries (Figure 24) and is below the recommended 30 metre wide, naturally vegetated target along 75 percent of the length of the catchment’s watercourses
No information available about instream aquatic and riparian conditions along Monahan Drain
Woodlands cover seven percent of the catchment and is below the 30 percent of forest cover that is identified as the minimum threshold for sustaining forest birds and other woodland dependent species (Figure 22)
Pre-settlement wetlands have declined by 99 percent and now cover less than one percent (12 ha.) of the catchment (Figure 23)
7.0 Monahan Drain Catchment: Opportunities/Actions
Target the Monahan Drain catchment to reduce loading via non-point and point source pollution control. Implement storm water and agricultural best management practices to address water quality concerns, including the protection of existing riparian cover and enhancement in areas where it is limited
Private landowners should consider taking advantage of The Rural Clean Water Programs which offer grants to landowners interested in implementing projects on their property that will help to protect and improve water quality.
- Homeowners may be interested in projects to repair, replace or upgrade their well or septic system, or addressing erosion through buffer plantings and erosion control
- Farmers can take advantage of a wide range of projects, including livestock fencing, manure storage, tile drainage control structures, cover crops, and many more
Continue to coordinate environmental monitoring and reporting activities with the City of Ottawa
Use wetland restoration as a tool to improve surface water quality and help restore the hydrologic integrity of the Jock River and its tributaries, including Monahan Drain
List, share and when possible, synthesize and use existing hydrological and geochemical datasets and assessment outcomes to facilitate the characterization of subwatershed and catchment hydrological functions. In addition, prepare guidance on best practices for the preparation of water budget assessments to better understand the hydrologic cycle requirements that occur at site specific scales; and share existing catchment and subwatershed scale water budget assessment outcomes
Monahan Drain flood risks are to be studied as part of ongoing efforts to prepare flood plain mapping for the Jock River subwatershed
Promote the Rideau Valley Shoreline Naturalization Program to landowners to increase existing eight percent of natural shoreline cover
Educate landowners about the value of and best management practices used to maintain and enhance natural shorelines and headwater drainage features
Work with the City of Ottawa to consistently implement current land use planning and development policies for water quality and shoreline protection (i.e., adherence to a minimum 30 metre development setback from water) adjacent to the Jock River and other catchment streams, including Monahan Drain
Target shoreline restoration at sites identified in this report (shown as “Other riparian land cover” in Figure 24) and explore other restoration and enhancement opportunities along the Monahan Drain and its tributaries
Promote the City of Ottawa Green Acres Reforestation Program to landowners to increase existing seven percent of woodland cover
Encourage the City of Ottawa to strengthen natural heritage and water resources policies in official plans and zoning by-laws where shoreline, wetland, woodland cover and watercourse setbacks are determined to be at or below critical ecological thresholds. Information for this purpose is provided in the RVCA’s subwatershed and catchment reports
Explore ways and means to more effectively enforce and implement conditions of land-use planning and development approvals to achieve net environmental gains
Re-consider the RVCA’s approach to wetland regulation where there is an identified hydrologic imperative to do so (i.e., significant loss of historic wetland cover (see Figure 23) and/or seasonal, critically low baseflows in the Jock River and/or areas of seasonal flooding)
Full Catchment Report