Jock River Subwatershed Report 2016
Hobbs 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 Hobbs 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 Hobbs Drain catchment
1.0 Hobbs Drain Catchment: Facts
1.1 General/Physical Geography
- Ottawa: (32 km2; 100% of catchment)
- Hobbs Drain Catchment resides within a transitionary area between the Ottawa Valley Clay Plain to the east and the Smith Falls Limestone Plain to the West. The southern half of the catchment is underlain by beach sands and gravels, sand plains and some areas of glacial till. Bedrock lies at the ground surface throughout the northern part of the catchment and is overlain, in areas by organic soils and localized areas of beach sands and gravels
- In this catchment, bedrock mostly consists of interbedded limestone and dolostone from the Gull River Formation. In addition, a geologic fault may pass through the catchment
- The ground surface ranges in elevation from approximately 155 masl south of Hwy 7 to approximately 96 masl at the catchment’s outlet
- 32 square kilometers; occupies six percent of the Jock River subwatershed, one percent of the Rideau Valley watershed
- Hobbs Drain and tributaries: 66 km
1.2 Vulnerable Areas
- The Mississippi-Rideau Source Protection initiative has mapped parts of the southern half of this catchment as a significant groundwater recharge area; and all the catchment as Highly Vulnerable Aquifer. Parts of Wellhead Protection Areas (WHPA) C and D for the municipal wells in Richmond underlie the northern extent of this catchment. In addition, parts of the WHPAs B and C for the municipal wells in Munster Hamlet, underlie part of this catchment near Bleeks Road
- 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 Hobbs Drain catchment
1.3 Conditions at a Glance
- Surface chemistry water quality rating along the Hobbs Drain is “Fair” from 2009 to 2014. The score at this site is largely influenced by occasional high nutrient concentrations, bacterial pollution and metal (aluminum) exceedances (see Figure 2)
- Instream biological water quality conditions at the Hobbs Drain sample location range from “ Poor” to “Excellent” from 2004 to 2015 (using a grading scheme developed by Ontario Conservation Authorities in Ontario for benthic invertebrates) with an overall benthic invertebrate water quality rating of “Good” determined for this period
Instream and Riparian
- Overall instream and riparian condition for the Hobbs 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)
- Wetland (39%)
- Crop and Pasture (29%)
- Woodland (15%)
- Transportation (6%)
- Meadow-Thicket (5%)
- Settlement (4%)
- Aggregate (2%)
Land Cover Type (2014)
- Crop and Pasture (31%)
- Woodland (26%)
- Wetland (24%)
- Settlement (8%)
- Meadow-Thicket (6%)
- Transportation (3%)
- Aggregate (2%)
- Water (<1%)
Land Cover Change (2008 to 2014)
- Woodland (-22 ha)
- Aggregate (-6 ha)
- Wetland (-3 ha)
- Meadow-Thicket (0 ha)
- Transportation (0 ha)
- Water (+7 ha)
- Settlement (+8 ha)
- Crop and Pasture (+16 ha)
Significant Natural Features
- Goulbourn Provincially Significant Wetland
- Richmond Fen Provincially Significant Wetland
- Several hundred (~250) operational private water wells in the Hobbs Drain Catchment. Groundwater uses are mainly domestic, but also include public water supplies, livestock watering and commercial uses
- There are parts of 3 bedrock quarry licenses located and 2 sand and gravel pits within the catchment. Sand and gravel resources are mainly of tertiary importance
Species at Risk (Elemental Occurrence)
- Spotted Turtle (Endangered)
- Blanding’s Turtle, Bobolink, Eastern Meadowlark (Threatened)
- Eastern Milksnake, Snapping Turtle, Yellow Rail (Special Concern)
1.4 Catchment Care
- Seventeen stewardship projects undertaken (see Section 5)
- Chemical surface (in-stream) water quality collection since 2003 (see Section 2)
- Benthic invertebrate (aquatic insect) surface (in-stream) water quality collection since 2003 (see Section 3.1.1)
- Six 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 level and chemistry data is available from PGMN wells located along Fernbank Road (W175) and in Stapledon (W084)
- Development along the Hobbs Drain and in and adjacent to the Provincially Significant Wetlands in the catchment (Goulbourn, Richmond Fen) are subject to Ontario Regulation 174-06 (entitled “Development, Interference with Wetlands and Alterations to Shorelines and Watercourses”) that protects the hydrologic function of the wetland and also protects landowners and their property from natural hazards (flooding, fluctuating water table, unstable soils) associated with them
- Two active Permits To Take Water (PTTW) in the Hobbs Drain catchment issued for pit /quarry dewatering
- Five Environmental Compliance Approvals and/or Environmental Activity and Sector Registrations in the Hobbs Drain Catchment. These are for a municipal or private sewage work; industrial sewage works; and a municipal drinking water system
2.0 Hobbs Drain Catchment: Surface Water Quality Conditions
Surface water quality conditions in the Hobbs Drain Catchment are monitored by the City of Ottawa 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 site in the Hobbs Drain Catchment
2.1 Hobbs Drain Water Quality Rating
The RVCA's water quality rating for Hobbs Drain (site JCK-247) is “Fair” (Table 1) as determined by the Canadian Council of Ministers of the Environment (CCME) Water Quality Index. 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. There is limited data available at this site prior to 2010, therefore only information for the 2010-2015 period will be discussed. Table 1 shows the overall rating for the monitored surface water quality site within the Hobbs Drain Catchment and Table 2 outlines the Water Quality Index (WQI) scores and their corresponding ratings.
There is one monitored water quality site on Hobbs Drain within this catchment (JCK-247, Figure 2). The score at this site is largely influenced by occasional high nutrient concentrations, bacterial pollution and metal (aluminum) exccedances. For more information on the CCME WQI, please see the Jock River Subwatershed Report.
Water Quality Index ratings for the Hobbs Drain Catchment
|Sampling Site||Location ||2004-2009||Rating|
|JCK-247||Hobbs Drain upstream of Bleeks Rd. bridge north east of Battlefield Rd.||NA||NA|
|Sampling Site||Location ||2010-2015||Rating|
|JCK-247||Hobbs Drain upstream of Bleeks Rd. bridge north east of Battlefield Rd.||78||Fair|Table 2
Water Quality Index 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 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 Hobbs Drain catchment and show the proportion of results that meet the guidelines.
Summary of total phosphorus results for Hobbs Drain catchment, 2010-2015
|Total Phosphorous 2010-2015|
|Site||Average (mg/l)||Below Guideline||No. Samples|
Summary of total Kjeldahl nitrogen results for Hobbs Drain catchment from 2010-2015. Highlighted values indicate average concentrations exceed the guideline
|Total Kjeldahl Nitrogen 2010-2015|
|Site||Average (mg/l)||Below Guideline||No. Samples|
Summary of ammonia results for Hobbs Drain catchment from 2010-2015
|Site||Average (mg/l)||Below Guideline||No. Samples|
Monitoring Site JCK-247
TP results rarely exceeded the PWQO at site JCK-247. Eighty-four percent of samples were below the guideline (Figure 3). The average TP concentration was below the objective at 0.020 mg/l as shown in Table 3.
The bulk of TKN results were elevated (Figure 4); only 25 percent of samples were below the guideline in the 2010-2015 period. The average concentrations exceeded the guideline at 0.610 mg/l (Table 4).
The results for NH3 indicate that exceedances occurred occasionally. Sixty-three percent of results were below the guideline in 2010-2015 reporting period (Figure 5). The average NH3 was 0.020 mg/l and just meets the PWQO (Table 5).
Figure 3 Total phosphorous concentrations in Hobbs Drain, 2010-2015
Figure 4 Total Kjeldahl nitrogen concentrations in Hobbs Drain, 2010-2015
Figure 5 Ammonia concentrations in Hobbs Drain, 2010-2015
Occasional nutrient enrichment is a feature in this reach of Hobbs Drain. The elevated TKN concentrations and moderate NH3 results provide evidence that elevated nutrients may be a natural feature in this part of the drain. Occasional exceedances of both NH3 and TP indicate that some nutrient loading may occur from upstream anthropogenic sources such as fertilizer use, agricultural activities and storm water runoff. Elevated nutrients may result in nutrient loading downstream and 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 (i.e. buffered shorelines, maintianing native shoreline vegetation, restricting livestock access to surface water, etc) should be employed wherever possible to limit nutrient loading to the waterbody.
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 site on the Hobb’s Drain 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 in the 2010-2015 period is shown in Figure 6.
Summary of E. coli
results for Hobbs Drain, 2010-2015. Highlighted values indicate the geometric mean exceeds the guideline
|E. coli 2010-2015|
|Site||Geometric Mean (CFU/100ml)||Below Guideline||No. Samples|
Monitoring Site JCK-247
Elevated E. coli counts at site JCK-247 were a common occurrence. The proportion of samples below the guideline was 33 percent (Figure 6). The geometric mean was 130 CFU/100ml (Table 6), and exceed the PWQO of 100 CFU/100ml.
Figure 6 Geometric mean of E. coli results in Hobbs Drain, 2010-2015
Bacterial pollution appears to be a concern at this site, the count at the geometric mean exceeds the PWQO and the majority of samples exceed the guideline. Best management practices such as enhancing shoreline buffers, minimizing storm water runoff and restricting livestock access to creeks can help to protect this reach of Hobbs Drain into the future.
Of the metals routinely monitored in Hobbs Drain Catchment, aluminum (Al) occasionally reported concentrations above the PWQO. In elevated concentrations metals can have toxic effects on sensitive aquatic species.
Table 7 summarizes metal concentrations at sites JCK-247 as well as show the proportion of samples that meet guidelines. Figure 7 shows metal concentrations with respect to the guideline (PWQO) of 0.075 mg/l.
Summary of aluminum results in Hobbs Drain from 2010-2015. Highlighted values indicate average concentrations exceed the guideline
|Site||Average (mg/l)||Below Guideline||No. Samples|
Monitoring Site JCK-247
The average Al concentration of 0.100 mg/l at site JCK-247 exceeded the guideline (Table 7). The majority of samples (56 percent) were below the guideline (Figure 7) from 2010-2015.
Figure 7 Average aluminum concentrations in Hobb’s Drain, 2010-2015
In the Hobbs Drain catchment aluminum concentrations often exceed the PWQO. The most elevated concentrations are observed during the spring likely due to increased runoff amounts from melt conditions, 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, fungicides and pesticides) to improve overall stream health and lessen downstream impacts.
1 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
2 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 Hobbs Drain Catchment: Riparian Conditions
3.1 Hobbs Drain Instream Aquatic Habitat
3.1.1 Benthic Invertebrates
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 Bleeks Road site on Hobbs Drain since 2004. 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.
Hilsenhoff Family Biotic Index
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 the Hobbs Drain catchment sample location at Bleeks Road are separated by reporting period 2004 to 2009 and 2010 to 2015. A wide ranging “Excellent” to “Poor” water quality conditions were observed at the Hobbs Drain sample location for the period from 2004 to 2015 (Figure 8) using a grading scheme developed by Conservation Authorities in Ontario for benthic invertebrates.
Figure 8 Hilsenhoff Family Biotic Index at the Hobbs Drain Bleeks Road sample location
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. The Hobbs Drain site is reported to have “Fair” to “Good” family richness (Figure 9).
Figure 9 Family Richness at the Hobbs Drain Bleeks Road sample location
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 more recent sampling years the community structure has been shifting to species that are more sensitive to poor water quality conditions. As a result, the EPT indicates that the Hobbs Drain sample location is reported to have “Fair” to “Good” water quality (Figure 10) from 2004 to 2015.
Figure 10 EPT at the Hobbs Drain Bleeks Road sample location
Site conditions at the Hobbs Drain Bleeks Road OBBN sample location at Bleeks Road
Overall the Hobbs Drain sample location aquatic habitat conditions from a benthic invertebrate perspective is considered “Good” from 2004 to 2015 as the samples are dominated by species that are moderately sensitive and sensitive to high organic pollution levels.
3.1.2 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 11 shows where the thermal sampling sites were located along Hobbs Drain. Analysis of the data collected indicates that Hobbs Drain is classified as a cool water system with cool to warm water reaches (Figure 12).
Figure 11 Temperature logger locations in the Hobbs Drain catchment
Figure 12 Temperature logger data for two sites on Hobbs 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
3.1.3 Fish Community
The Hobbs Drain catchment is classified as a mixed community of warm and cool water recreational and baitfish fishery with 23 species observed. Figure 13 shows the sampling locations in the Hobbs Drain catchment.
Figure 13 Hobbs Drain catchment fish community
Hobbs Drain fish sampling location
The following table contains a list of species observed in the watershed.
Fish species observed in Hobbs Drain catchment
|Fish Species||Fish code||Fish Species||Fish code|
|blackchin shiner||BcShi||fathead minnow||FhMin|
|blacknose dace||BnDac||finescale dace||FsDac|
|blacknose shiner||BnShi||hornyhead chub||HhChu|
|bluntnose minnow||BnMin||longnose dace||LnDac|
|brassy minnow||BrMin||northern pearl dace||PeDac|
|brook stickleback||BrSti||northern pike||NoPik|
|carps and minnows||CA_MI||northern redbelly dace||NRDac|
|chrosomus sp.||PhoSp||spotfin shiner||SpShi|
|common shiner||CoShi||white sucker||WhSuc|
3.2 Headwater Drainage Features Assessment
3.2.1 Headwater 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 6 sites at road crossings in the Hobbs Drain catchment area (Figure 14).
Figure 14 Locations of the headwater sampling sites in the Hobbs 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. Five features were classified as having been channelized and one feature was identified as natural. Figure 15 shows the feature type of the primary feature at the sampling locations.
Figure 15 Headwater feature types in the Hobbs 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 16 shows the observed flow conditions at the sampling locations in the Hobbs Drain catchment in 2015.
Figure 16 Headwater feature flow conditions in the Hobbs Drain catchment
A summer photo of the headwater sample site in the Hobbs Drain catchment located on Fernbank Road
3.2.4 Feature Channel Modifications
Channel modifications were assessed at each headwater drainage feature sampling location. Modifications include dredging, channel hardening and mixed modifications. The Hobbs Drain catchment area had one site classified as having no channel modifications, two features were classified as being hardened, two had been dredged and one had mixed modifications. Figure 17 shows the channel modifications observed at the sampling locations for Hobbs Drain.
Figure 17 Headwater feature channel modifications in the Hobbs 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 Hobbs Drain catchment were classified being dominated by wetland and meadow vegetation. Figure 18 depicts the dominant vegetation observed at the sampled headwater sites in the Hobbs Drain catchment.
Figure 18 Headwater feature vegetation types in the Hobbs 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. Three sample locations in Hobbs Drain were dominated by natural vegetation in the form of scrubland, meadow and wetland vegetation. Three sample locations were dominated by other forms of vegetation of either crops or ornamental grasses. Figure 19 depicts the type of riparian vegetation observed at the sampled headwater sites in the Hobbs Drain catchment.
Figure 19 Headwater feature riparian vegetation types in the Hobbs 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 20 depicts the degree of sediment deposition observed at the sampled headwater sites in the Hobbs Drain catchment.
Figure 20 Headwater feature sediment deposition in the Hobbs 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 Hobbs Drain catchment area ranged from minimal to high roughness conditions. Figure 21 shows the feature roughness conditions at the sampling locations in the Hobbs Drain catchment.
Figure 21 Headwater feature roughness in the Hobbs Drain catchment
4.0 Hobbs Drain Catchment: Land Cover
Land cover and any change in coverage that has occurred over a six year period is summarized for the Hobbs 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 Hobbs Drain Catchment Change
As shown in Table 9, the dominant land cover type in 2014 was crop and pastureland, followed by woodland and wetland.
Land cover (2008 vs. 2014) in the Hobbs Drain catchment
| Land Cover||2008||2014||Change - 2008 to 2014|
|Crop & Pasture||978||31||994||31||16||0|
* Does not include treed swamps ** Includes treed swamps
From 2008 to 2014, there was an overall change of 44 hectares (from one land cover class to another). Most of the change in the Hobbs Drain catchment is a result of the conversion of woodland to crop and pastureland (Figure 22).
Figure 22 Land cover change in the Hobbs Drain catchment (2014)
Table 10 provides a detailed breakdown of all land cover change that has taken place in the Hobbs Drain catchment between 2008 and 2014.
Land cover change in the Hobbs Drain catchment (2008 to 2014)
|Land Cover||Change - 2008 to 2014|
|Wooded Area to Crop and Pasture||23.6||53.0|
|Aggregate to Water||6.7||15.1|
|Crop and Pasture to Wooded Area||5.4||12.2|
|Wooded Area to Settlement||3.8||8.5|
|Unevaluated Wetland to Settlement||2.3||5.3|
|Wooded Area to Aggregate||1.8||4.1|
|Crop and Pasture to Settlement||0.8||1.8|
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 23, 30 percent of the Hobbs Drain catchment contains 847 hectares of upland forest and 111 hectares of lowland forest (treed swamps) versus the 26 percent of woodland cover in the Jock River subwatershed. This equals 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 23 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 Hobbs Drain catchment (in 2014), eighty-two (52 percent) of the 156 woodland patches are very small, being less than one hectare in size. Another 63 (40 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 11 (eight percent of) woodland patches range between 22 and 120 hectares in size. Ten 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, one (one percent) of the 156 woodland patches in the drainage area exceeds the 100 plus hectare size needed to support most forest dependent, area sensitive birds and is 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 11 presents a comparison of woodland patch size in 2008 and 2014 along with any changes that have occurred over that time. A decrease (of 23 ha) has been observed in the overall woodland patch area between the two reporting periods with most change occurring in the 50 to 100 hectare woodland patch size class range.
Woodland patches in the Hobbs Drain catchment (2008 and 2014)
|Woodland Patch Size Range (ha) ||Woodland* Patches||Patch Change|
|2008||2014||2008 to 2014|
|Number ||Area ||Number ||Area ||Number ||Area |
|Count ||Percent || Ha ||Percent ||Count ||Percent || Ha ||Percent||Count ||Ha |
|Less than 1 ||75||50||31||3||82||52||34||4||7||3|
|1 to 20 ||64||43||291||30||63||40||289||30||-1||-2|
|20 to 50 ||4||3||125||13||4||3||125||13||0||0|
|50 to 100 ||6||4||415||42||6||4||391||41||0||-24|
|100 to 200 ||1||1||120||12||1||1||120||12||0||0|
*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 Hobbs Drain catchment (in 2014), the 156 woodland patches contain 36 forest interior patches (Figure 23) that occupy three percent (89 ha.) of the catchment land area (which is equivalent to 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 (35) have less than 10 hectares of interior forest, 21 of which have small areas of interior forest habitat less than one hectare in size. Between 2008 and 2014, there has been an increase in the number of woodland patches containing smaller areas of interior habitat with an overall gain of three hectares in the catchment (Table 12), suggesting an increase in forest fragmentation over the six year period.
Table 12 Woodland Interior in the Hobbs Drain catchment (2008 and 2014)
|Woodland Interior Habitat Size Range (ha)||Woodland Interior||Interior Change|
|2008||2014||2008 to 2014|
|Less than 1 ||8||40||3||4||21||58||5||6||13||2|
|1 to 10||9||45||39||45||14||39||65||73||5||26|
|10 to 30||3||15||44||51||1||3||19||21||-2||-25|
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 13).
Wetland cover in the Jock River subwatershed and Hobbs Drain catchment (Historic to 2014)
|Wetland Cover ||Pre-settlement||2008||2014||Change - Historic to 2014|
|Area ||Area ||Area ||Area |
|Ha ||Percent ||Ha ||Percent ||Ha ||Percent ||Ha ||Percent |
This decline in wetland cover is also evident in the Hobbs Drain catchment (as seen in Figure 24) where wetland was reported to cover 28 percent of the area prior to settlement, as compared to 24 percent in 2014. This represents a 17 percent loss of historic wetland cover. To maintain critical hydrological, ecological functions along with related recreational and economic benefits provided by these wetland habitats in the catchment, a “no net loss” of currently existing wetlands should be employed to ensure the continued provision of tangible benefits accruing from them to landowners and surrounding communities.
Figure 24 Hobbs Drain 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 25 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 Hobbs Drain catchment.
Figure 25 Natural and other riparian land cover in the Hobbs Drain catchment
This analysis shows that the riparian zone in the Hobbs Drain catchment in 2014 was comprised of wetland (39 percent), crop and pastureland (29 percent), woodland (15 percent), transportation (six percent), meadow-thicket (five percent), settlement (four percent) and aggregates (two percent). Additional statistics for the Hobbs Drain catchment are presented in Table 14 and show that there has been very little change in shoreline cover from 2008 to 2014.
Riparian land cover (2008 vs. 2014) in the Hobbs Drain catchment
|Riparian Land Cover||2008||2014||Change - 2008 to 2014|
|Crop & Pasture||112||29||113||29||1||0|
5.0 Hobbs 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 26 shows the location of all stewardship projects completed in the Hobbs Drain catchment along with sites identified for potential shoreline restoration.
5.1 Rural Clean Water Projects
From 2010 to 2015, one well decommissioning was completed and between 2004 and 2009, two well upgrades and one septic system replacement were completed. Total value of the four projects is $24,594 with $3,684 of that amount funded through grant dollars from the RVCA.
Figure 26 Stewardship site locations
5.2 Private Land Forestry Projects
The location of RVCA tree planting projects is shown in Figure 26. From 2010 to 2015, 5,000 trees were planted at one site. Between 2004 and 2009, 2,700 trees were planted at two sites and prior to 2004, 16,350 trees were planted at five sites, In total, 24,050 trees were planted resulting in the reforestation of 12 hectares. One of these projects was completed within the 30 metre riparian zone of the Hobbs Drain. Total project value of all eight projects is $82,426 with $30,779 of that amount coming from fundraising sources.
Through the RVCA Butternut Recovery Program, an additional 10 butternut trees were planted in the Hobbs Drain catchment (Figure 26) between 2010 and 2015, as part of efforts to introduce healthy seedlings from tolerant butternuts into various locations across Eastern Ontario.
5.3 Ontario Drinking Water Stewardship Projects
Figure 26 shows the location of all Ontario Drinking Water Stewardship Program (ODWSP) projects in the Hobbs Drain catchment. From 2010 to 2015, five fuel handling and storage facilities were constructed at a total value of $29,108 with $3,569 of that amount funded by the Ontario Ministry of the Environment.
5.4 Valley, Stream, Wetland and Hazard Lands
The Hobbs Drain catchment covers 32 square kilometres with 4.5 square kilometres (or 14 percent) of the drainage area being within the regulation limit of Ontario Regulation 174/06 (Figure 27), giving protection to wetland areas and river or stream valleys that are affected by flooding and erosion hazards.
Wetlands occupy 7.6 sq. km. (or 24 percent) of the catchment. Of these wetlands, 4.2 sq. km (or 56 percent) are designated as provincially significant and included within the RVCA regulation limit. This leaves the remaining 3.3 sq. km (or 44 percent) of wetlands in the catchment outside the regulated area limit.
Of the 65.8 kilometres of stream in the catchment, regulation limit mapping has been plotted along 11.8 kilometers of streams (representing 18 percent of all streams in the catchment). Some of these regulated watercourses (9.7 km or 15 percent of all streams) flow through regulated wetlands; the remaining 2.1 km (or 18 percent) of regulated streams are located outside of those wetlands. Plotting of the regulation limit on the remaining 54 km (or 82 percent) of streams requires identification of flood and erosion hazards and valley systems.
Within those areas of the Hobbs Drain catchment subject to the 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. For areas beyond the regulation limit, protection of the catchment’s watercourses is only provided through the “alteration to waterways” provision of the regulation.
Figure 27 RVCA regulation limits
5.5 Vulnerable Drinking Water Areas
A portion of the Wellhead Protection Area around the Munster municipal drinking water source is located within the Hobbs Drain drainage catchment. This area is subject to mandatory policies in the Mississippi-Rideau Source Protection Plan developed under the Clean Water Act. These policies specifically regulate land uses and activities that are considered drinking water threats, thereby reducing the risk of contamination of the municipal drinking water source.
The Hobbs Drain drainage catchment is also 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.
The lands immediately to the west and north of Munster Hamlet are also considered a Significant Groundwater Recharge Area. This means that there is a volume of water moving from the surface into the ground and groundwater serves either as a municipal drinking water source or supplies a coldwater ecosystem such as a brook trout stream. The Plan was not required to include policies to specifically address Significant Groundwater Recharge Areas.
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.
6.0 Hobbs Drain Catchment: Challenges/Issues
Surface chemistry water quality rating along the Hobbs Drain is “Fair”. The score at this site is largely influenced by occasional high nutrient concentrations, bacterial pollution and metal (aluminum) exceedances.
Instream biological water quality conditions at the Hobbs Drain sample location range from “ Poor” to “Excellent” from 2004 to 2015 (using a grading scheme developed by Ontario Conservation Authorities in Ontario for benthic invertebrates) with an overall benthic invertebrate water quality rating of “Good” determined for this period.
Natural hazard lands have not been identified.
Drainage problems have led to establishment of altered wetland conditions and land use conflict (amongst development, quarry, agriculture and wetland conservation interests).
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 58 percent of the riparian zone of the Hobbs Drain and its tributaries (Figure 25 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 Hobbs Drain
Woodlands cover 30 percent of the catchment and equals the 30 percent of forest cover that is identified as the minimum threshold for sustaining forest birds and other woodland dependent species (Figure 23)
Pre-settlement wetlands have declined by 17 percent and now cover 24 percent (756 ha.) of the catchment (Figure 24). Forty-four percent (334 ha.) of these wetlands remain unevaluated/unregulated and are vulnerable to drainage and land clearing activities in the absence of any regulatory and planning controls that would otherwise protect them for the many important hydrological, social, biological and ecological functions/services/values they provide to landowners and the surrounding community
7.0 Hobbs Drain Catchment: Opportunities/Actions
Offer the suite of water quality improvement projects (including the new tile drainage control outlet management funding) provided by the Rideau Valley Rural Clean Water Program to landowners where opportunities exist to manage rural runoff to the Hobbs Drain and tributaries:
- 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 Hobbs 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
Flewellyn Special Study Area, Cumulative Effects Study has been initiated by the City of Ottawa to better understand the hydrology in the area and associated drainage concerns
Hobbs 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 39 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 watercourses, including the Hobbs Drain
Target shoreline restoration at sites identified in this report (shown as “Other riparian land cover” in Figure 25) and explore other restoration and enhancement opportunities along the Hobbs Drain and its tributaries
Promote the City of Ottawa’s Green Acres Reforestation Program to landowners to increase existing 30 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 24) and/or seasonal, critically low baseflows in the Jock River and/or areas of seasonal flooding)
Full Catchment Report