Otty Lake - Jebbs Creek

3.0  Otty Lake Catchment: Riparian Conditions

The RVCA Stream Characterization Program evaluated 3.9 km of Jebbs Creek in 2016.  A total of 39 stream survey assessments were completed in the month of June and the first week of July. 

During the summer and fall of 2016, the Rideau Valley watershed experienced periods of severe drought. Precipitation levels were measured at less than 40% of the long-term average, as the water supply was unable to meet local demand. The lack of rainfall affected the success and function of farm crops, municipal and private wells, lawns and gardens, navigation and ultimately the health of our lakes, rivers and streams.

Low water conditions were readily observed throughout the watershed, as many of the streams were highly fragmented or completely dry (see photo below). Aquatic species such as amphibians, fish and  benthic invertebrates were affected, as suitable habitat may have been limited.

3.1 Jebbs Creek Overbank Zone

3.1.1 Riparian Buffer Evaluation

The quality of the riparian area increases with the width, complexity and linear extent of its vegetation along a stream or creek. A complex riparian community consists of diverse plant species native to the site, with multiple age-classes providing vertical structural diversity along a watercourse.

Here is a list of watershed benefits from a healthy riparian buffer zone:

• Reduces the amount of pollutants that reach the stream from surface runoff
• Helps reduce and mitigate erosion
• Provides a microclimate that is cooler during the summer months providing cooler water for aquatic organisms
• Provides large wood structure from fallen trees and limbs that form instream cover, create pools, stabilize the streambed, and provide habitat for aquatic organisms
• Provides organic material for stream biota that, among other functions, is the base of the food chain in lower order streams
• Provides habitat for terrestrial insects that drop in the stream and become food for fish and travel corridors for other terrestrial animals
• Dissipates energy during flood events
• Often provides the only refuge areas for fish during out-of-bank flows (behind trees, stumps, and logs)

Figure 26 demonstrates the buffer conditions of the left and right banks separately.  Jebbs Creek had a buffer of greater than 30 meters along 91 percent of the right bank and 97 percent of the left bank.

3.1.2 Riparian Buffer Alterations

Alterations within the riparian buffer were assessed within three distinct shoreline zones (0-5m, 5-15m, 15-30m), and evaluated based on the dominant vegetative community and/or land cover type (Figure 27). The riparian buffer zone along Jebbs Creek was found to be dominated by forest and wetland conditions along the riparian corridor.

3.1.3 Adjacent Land Use

The RVCA’s Stream Characterization Program identifies seven different land uses along Jebbs Creek (Figure 28). Surrounding land use is considered from the beginning to end of the survey section (100m) and up to 100m on each side of the river. Land use outside of this area is not considered for the surveys but is nonetheless part of the subwatershed and will influence the creek. Natural areas made up 96 percent of the stream, characterised by forest, scrubland, meadow and wetland. Wetland habitat was dominant in the adjacent lands along Jebbs Creek at 84 percent of the surveyed sections. The remaining land use consisted of industrial/commercial, residential and other in the form of hydro infrastructure.

3.2 Jebbs Creek Shoreline Zone

3.2.1 Instream Erosion

Stream erosion is the process by which water erodes and transports sediments, resulting in dynamic flows and diverse habitat conditions.  Excessive erosion can result in drastic environmental changes, as habitat conditions, water quality and aquatic life are all negatively affected.  Bank stability was assessed as the overall extent of each section with “unstable” shoreline conditions.  These conditions are defined by the presence of significant exposed soils/roots, minimal bank vegetation, severe undercutting, slumping or scour and potential failed erosion measures. The majority of Jebbs Creek had low levels of erosion with the exception of one location along the system which had moderate levels of erosion near the confluence with the Tay marsh (Figure 29).

3.2.2 Undercut Stream Banks

Stream bank undercuts can provide excellent cover habitat for aquatic life, however excessive levels can be an indication of unstable shoreline conditions.  Bank undercut was assessed as the overall extent of each surveyed section with overhanging bank cover present. Figure 30 shows that Jebbs Creek had low levels of undercut banks along the majority of the system which is typical for systems that are dominated by riverine wetland habitat along the shoreline. 

3.2.3 Stream Shading

Grasses, shrubs and trees all contribute towards shading a stream. Shade is important in moderating stream temperature, contributing to food supply and helping with nutrient reduction within a stream.  Stream cover is assessed as the total coverage area in each section that is shaded by overhanging trees/grasses and tree canopy, at greater than one metre above the water surface.  Figure 31 shows highly variable conditions of none to high levels of stream shading along Jebbs Creek.

3.2.4 Instream Wood Structure

Forested shorelines provide essential complex habitat through the perpetual process of shoreline trees falling into the water.  This continuous recruitment of trees creates a wood-based physical structure in the littoral zone that is common on natural systems.  Insects, fish, amphibians, birds, and other animals have also evolved with this abundance of near shore wood and it is essential to their life cycles. With increased development along many waterways, forested lakeshores have been altered and wood-based physical structure in many waterways has been reduced. It is important to restore this essential habitat to aquatic ecosystems.

Shoreline Protection

• Protects shorelines by providing a barrier from wind and wave erosion
• Reduces sedimentation of the water caused by shoreline slumping due to bank erosion
• Allows detritus to collect and settle on the lake or creek bed providing the substrate structure required for native aquatic vegetation to establish and outcompete invasive species

Food Source

• Wood complexes are an important food source for invertebrates 
• Small fish feed on the abundance of invertebrates that are found around these structures
• Larger fish, waterfowl and shorebirds all benefit from the abundance of invertebrates and small fish feeding around woody structures in the littoral zone 

Cover

• Cover from predators is essential for many fish and animals to successfully complete their life cycle
• The nooks and crannies of wood complexes offer critters safety from predators while at the same time concentrating prey to make predators more efficient
• Wood provides the structure on which many species must lay or attach their eggs, therefore these complexes provide quality spawning and nesting habitat

Diversity

• Wood complexes in the littoral zone provide unique edge habitat along the shoreline
• Edge habitats contain more species diversity and higher concentrations of species than the adjoining habitats themselves will have

Figure 32 shows that the majority of Jebbs Creek had low to moderate levels of instream wood structure in the form of branches and trees along the system.

3.2.5 Overhanging Wood Structure

Trees and branches that are less than one meter from the surface of the water are defined as overhanging.  Overhanging wood structure provide a food source, nutrients and shade which helps to moderate instream water temperatures. Figure 33 shows the system is dominated by low to moderate levels of overhanging branches and trees along Jebbs Creek.

3.2.6 Anthropogenic Alterations

Stream alterations are classified based on specific functional criteria associated with the flow conditions, the riparian buffer and potential human influences.  Figure 34 shows 74 percent of Jebbs Creek remains “unaltered” with no anthropogenic alterations.   Eighteen percent of Jebbs Creek was classified as natural with minor anthropogenic changes, while eight percent was considered altered.  The alterations along Jebbs Creek were in the form of a road crossing and areas with reduced natural buffers.

3.3 Jebbs Creek Instream Aquatic Habitat

3.3.1 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 Perth Wildlife Reserve site on Jebbs Creek since 2003. Monitoring data is analysed for each sample site and the results are presented using the Family Biotic Index, Family Richness and percent Ephemeroptera, Plecoptera and Trichoptera.  There were no values recorded for the Fall of 2016 due to extreme drought conditions therefore no samples could be collected.

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 Jebbs Creek catchment sample location at the Perth Wildlife Reserve are summarised by year from 2005 to 2016.  “Fair” to “Poor” water quality conditions were observed at the Jebbs Creek sample location (Figure 35) using a grading scheme developed by Conservation Authorities in Ontario for benthic invertebrates.   

Family Richness

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 Jebbs Creek site is reported to have “Fair” family richness (Figure 36).

EPT

Ephemeroptera (Mayflies), Plecoptera (Stoneflies), and Trichoptera (Caddisflies) are species considered to be very sensitive to poor water quality conditions. A high abundance of these organisms is generally an indication of good water quality conditions at a sample location.  The community structure is typically dominated by species that are moderately tolerant and tolerant to poorer water quality conditions at the Jebbs Creek sample location.  As a result, the EPT indicates that the Jebbs Creek sample location is reported to have “Fair” to “Poor” water quality (Figure 37) from 2005 to 2016.

Conclusion

Overall the Jebbs Creek sample location aquatic habitat conditions from a benthic invertebrate perspective is considered “Fair to Poor” from 2005 to 2016 as the samples are dominated by species that are moderately tolerant and tolerant to high organic pollution levels.

3.3.2 Habitat Complexity

Habitat complexity is a measure of the overall diversity of habitat types and features within a stream. Streams with high habitat complexity support a greater variety of species niches, and therefore contribute to greater diversity. Factors such as substrate, flow conditions (pools, riffles) and cover material (vegetation, wood structure, etc.) all provide crucial habitat to aquatic life.  Habitat complexity is assessed based on the presence of boulder, cobble and gravel substrates, as well as the presence of instream woody material.

Low to high habitat complexity was identified for Jebbs Creek (Figure 38). Regions with increased habitat complexity were observed in the lower and upper reaches of the system within the catchment.

3.3.3 Instream Substrate

Diverse substrate is important for fish and benthic invertebrate habitat because some species have specific substrate requirements and for example will only reproduce on certain types of substrate.  The absence of diverse substrate types may limit the overall diversity of species within a stream. Figure 39 shows the overall presence of various substrate types observed along Jebbs Creek.  Substrate conditions were somewhat diverse along Jebbs Creek with all substrate types being recorded at various locations along the creek.  Silt was the dominant substrate type observed along Jebbs Creek which is consistent with riverine wetland habitat. Figure 40 shows the dominant substrate type observed for each section surveyed along Jebbs Creek. 

3.3.4 Instream Morphology

Pools and riffles are important habitat features for aquatic life.  Riffles are fast flowing areas characterised by agitation and overturn of the water surface. Riffles thereby play a crucial role in contributing to dissolved oxygen conditions and directly support spawning for some fish species.  They are also areas that support high benthic invertebrate populations which are an important food source for many aquatic species.  Pools are characterised by minimal flows, with relatively deep water and winter/summer refuge habitat for aquatic species.  Runs are moderately shallow, with unagitated surfaces of water and areas where the thalweg (deepest part of the channel) is in the centre of the channel. Figure 41 shows that Jebbs Creek is fairly uniform; 100 percent of sections recorded runs, five percent riffles and 33 percent of sections contained pool habitat. Figure 42 shows where the limited riffle habitat areas were observed along Jebbs Creek.

3.3.5 Vegetation Type

Instream vegetation provides a variety of functions and is a critical component of the aquatic ecosystem.  Aquatic plants promote stream health by:

• Providing direct riparian/instream habitat
• Stabilising flows reducing shoreline erosion
• Contributing to dissolved oxygen through photosynthesis
• Maintaining temperature conditions through shading

For example emergent plants along the shoreline can provide shoreline protection from wave action and important rearing habitat for species of waterfowl.  Submerged plants provide habitat for fish to find shelter from predator fish while they feed.  Floating plants such as water lilies shade the water and can keep temperatures cool while reducing algae growth.  Floating plants were observed in 95% of sections surveyed, algae was observed in 90% of sections, narrow leaved emergents were present in 72% of the sections surveyed, while free floating plants were observed in 44% of surveyed sections.  Broad leaved emergents were observed in 44% of sections, submerged plants in 56% and robust emergents in 15% of sections surveyed.  Figure 43 depicts the plant community structure for Jebbs Creek. Figure 44 shows the dominant vegetation type observed for each section surveyed along the Jebbs Creek catchment.

3.3.6 Instream Vegetation Abundance

Instream vegetation is an important factor for a healthy stream ecosystem. Vegetation helps to remove contaminants from the water, contributes oxygen to the stream, and provides habitat for fish and wildlife. Too much vegetation can also be detrimental. Figure 45 demonstrates that the Jebbs Creek reach had normal to common levels of vegetation recorded at 36 and 90 percent of stream surveys.  Extensive levels of vegetation were observed along 64 percent of the surveyed sections and were consistent with areas dominated by the invasive plant known as European Frogbit.

3.3.7 Invasive Species

Invasive species can have major implications on streams and species diversity. Invasive species are one of the largest threats to ecosystems throughout Ontario and can out compete native species, having negative effects on local wildlife, fish and plant populations. One hundred percent of the sections surveyed along Jebbs Creek reach contained invasive species. The invasive species observed in Jebbs Creek were European frogbit and banded mystery snail.  Invasive species abundance (i.e. the number of observed invasive species per section) was assessed to determine the potential range/vector of many of these species (Figure 46).

3.3.8 Water Chemistry

During the stream characterization survey, a YSI probe is used to collect water chemistry information.  Dissolved oxygen (DO), specific conductivity (SPC) and pH are measured at the start and end of each section. 

3.3.8.1 Dissolved Oxygen

Dissolved oxygen is a measure of the amount of oxygen dissolved in water. The Canadian Environmental Quality Guidelines of the Canadian Council of Ministers of the Environment (CCME) suggest that for the protection of aquatic life the lowest acceptable dissolved oxygen concentration should be 6 mg/L for warmwater biota and 9.5 mg/L for coldwater biota (CCME, 1999).  Figure 47 shows that the dissolved oxygen in Jebbs Creek supports warmwater and in certain locations coldwater biota along the system.  The average dissolved oxygen levels observed within Jebbs Creek was 9.5mg/L which is well above the recommended levels for warmwater biota. 

3.3.8.2 Conductivity

Conductivity in streams is primarily influenced by the geology of the surrounding environment, but can vary drastically as a function of surface water runoff. Currently there are no CCME guideline standards for stream conductivity; however readings which are outside the normal range observed within the system are often an indication of unmitigated discharge and/or stormwater input. The average conductivity observed within the main stem of Jebbs Creek was 262.5 µs/cm. Figure 48 shows the conductivity readings for Jebbs Creek.

3.3.8.3 pH

Based on the PWQO for pH, a range of 6.5 to 8.5 should be maintained for the protection of aquatic life. Average pH values for Jebbs Creek averaged 7.94 thereby meeting the provincial standard (Figure 49).

3.3.8.4 Oxygen Saturation (%)

Oxygen saturation is measured as the ratio of dissolved oxygen relative to the maximum amount of oxygen that will dissolve based on the temperature and atmospheric pressure. Well oxygenated water will stabilise at or above 100% saturation, however the presence of decaying matter/pollutants can drastically reduce these levels. Oxygen input through photosynthesis has the potential to increase saturation above 100% to a maximum of 500%, depending on the productivity level of the environment. In order to represent the relationship between concentration and saturation, the measured values have been summarised into 6 classes:

Dissolved oxygen conditions in Jebbs Creek varied along the system for both warm and coolwater species (Figure 50).

3.3.8.5 Specific Conductivity Assessment

Specific conductivity (SPC) is a standardised measure of electrical conductance, collected at or corrected to a water temperature of 25⁰C. SPC is directly related to the concentration of ions in water, and is commonly influenced by the presence of dissolved salts, alkalis, chlorides, sulfides and carbonate compounds. The higher the concentration of these compounds, the higher the conductivity. Common sources of elevated conductivity include storm water, agricultural inputs and commercial/industrial effluents.

In order to summarise the conditions observed, SPC levels were evaluated as either normal, moderately elevated or highly elevated. These categories correspond directly to the degree of variation (i.e. standard deviation) at each site relative to the average across the system.

Normal levels were maintained along the majority of Jebbs Creek, however there were moderately elevated areas in the middle reaches (Figure 51).

3.3.9 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 52 shows where the thermal sampling site was located on Jebbs Creek.  Analysis of the data collected indicates that Jebbs Creek is classified as a warm water system (Figure 53).  

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

3.3.10 Groundwater

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 54 shows areas where one or more of the above groundwater indicators were observed during stream surveys and headwater drainage feature assessments. 

3.3.11 Fish Community

The Otty Lake catchment is classified as a mixed community of warm and cool water recreational and baitfish fishery with 19 species observed. Figure 55 shows the historical and 2016 fish sampling locations in the catchment. 

Table 13 is a list of species observed in the watershed historically and during the 2016 sampling effort.

3.3.12 Migratory Obstructions

Migratory obstructions represent limitations to fish dispersal within a system and may restrict access to important spawning and rearing habitat. Migratory obstructions can be natural or manmade, and they can be permanent or seasonal. Figure 56 shows the migratory obstructions observed for the Otty Lake catchment.  

3.3.13 Beaver Dams

Overall beaver dams create natural changes in the environment. Some of the benefits include providing habitat for wildlife, flood control, and silt retention. Additional benefits come from bacterial decomposition of woody material used in the dams which removes excess nutrient and toxins. Beaver dams can also result in flooding of agricultural fields and may also be considered potential barriers to fish migration.  Figure 57 shows the types of beaver dams that were identified on the surveyed portions of Jebbs Creek in 2016.

3.4 Headwater Drainage Feature Assessment

3.4.1 Headwaters Sampling Locations

The RVCA Stream Characterization program assessed Headwater Drainage Features for the Otty Lake catchment in 2017. 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 2017 the program sampled 32 sites at road crossings in the Otty Lake catchment area (Figure 58).  

3.4.2 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.  The headwater drainage features in the Otty Lake catchment are primarily classified as wetland and natural features.  Figure 59 shows the feature type of the primary feature at the sampling locations.

3.4.3 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 60 shows the observed flow condition at the sampling locations in the Otty Lake catchment in 2017.

3.4.4 Feature Channel Modifications

Channel modifications were assessed at each headwater drainage feature sampling location.  Modifications include channelization, dredging, hardening and realignments.  Figure 61 shows the channel modifications observed at the sampling locations for the Otty Lake.  The majority of the headwater features had no modifications observed at the sample locations.

3.4.5 Headwater Feature Vegetation

Headwater feature vegetation evaluates the type of vegetation that is found within the drainage feature. The type of vegetation 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 were classified as being dominated by wetland and meadow.  Figure 62 depicts the dominant vegetation observed at the sampled headwater sites in the Otty Lake catchment.

3.4.6 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.  The sample locations were dominated by natural vegetation.  Figure 63 depicts the type of riparian vegetation observed at the sampled headwater sites in the Otty Lake catchment.

3.4.7 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 64 depicts the degree of sediment deposition observed at the sampled headwater sites in the Otty Lake catchment.

3.4.8 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 to aquatic organisms. Figure 65 shows the feature roughness conditions at the sampling location in the Otty Lake catchment.

4.0 Otty Lake Catchment: Land Cover

Land cover and any change in coverage that has occurred over a six year period is summarised for the Otty Lake 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 Otty Lake Catchment Change

As shown in Table 14 and Figure 1 (see the Introduction section of this report), the dominant land cover type in 2014 is woodland.

From 2008 to 2014, there was an overall change of 11 hectares (from one land cover class to another). Most of the change in the Otty Lake catchment is a result of the conversion of crop and pastureland, meadow-thicket and woodland to settlement (Figure 66).

Table 15 provides a detailed breakdown of all land cover change that has taken place in the Otty Lake catchment between 2008 and 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 Tay 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 specialised 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 67, 41 percent of the Otty Lake catchment contains 2133 hectares of upland forest and 42 hectares of lowland forest (treed swamps) versus the 47 percent of woodland cover in the Tay River subwatershed. This is greater than the 30 percent of forest cover that is identified as the minimum threshold required to sustain forest birds according to the Guideline and which may only support less than one half of potential species richness and marginally healthy aquatic systems. When forest cover drops below 30 percent, forest birds tend to disappear as breeders across the landscape.

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 specialised 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 Otty Lake catchment (in 2014), one hundred and forty-eight (52 percent) of the 285 woodland patches are very small, being less than one hectare in size. Another 121 (42 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 16 (six percent of) woodland patches range between 22 and 709 hectares in size. Thirteen 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, three (one percent) of the 285 woodland patches in the drainage area exceed the 100 plus hectare size needed to support most forest dependent, area sensitive birds and are large enough to support approximately 60 percent of edge-intolerant species. One 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 16 presents a comparison of woodland patch size in 2008 and 2014 along with any changes that have occurred over that time. A decrease (of seven hectares) has been observed in the overall woodland patch area between the two reporting periods with most change occurring in the 1 to 20 woodland patch size class range.

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 Otty Lake catchment (in 2014), the 285 woodland patches contain 26 forest interior patches (Figure 67) that occupy three percent (147 ha.) of the catchment land area (which is less than the five percent of interior forest in the Tay 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 (23) have less than 10 hectares of interior forest, fifteen of which have small areas of interior forest habitat less than one hectare in size. The remaining three patches contain interior forest between 11 and 90 hectares in area. Between 2008 and 2014, there has been a small change in the number of woodland patches containing interior habitat with an overall loss of four hectares in the catchment (Table 17).

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 stabilisation 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.

This decline in wetland cover is also evident in the Otty Lake catchment (as seen in Figure 68 and summarised in Table 18), where wetland was reported to cover 31 percent of the area prior to settlement, as compared to 21 percent in 2014. This represents a 31 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.

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 69 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 around Otty and McLaren Lake, other lakes and along both sides of the shoreline of Jebbs Creek and the many unnamed watercourses (including headwater streams) found in the Otty Lake catchment.                                              

This analysis shows that the Otty Lake catchment riparian buffer is composed of wetland (44 percent), woodland (37 percent), crop and pastureland (eight percent), settlement (eight percent), roads (two percent) and meadow-thicket (one percent). Along the many watercourses (including headwater streams) flowing into Otty and McLaren Lake, the riparian buffer is composed of wetland (51 percent), woodland (32 percent), crop and pastureland (12 percent), roads (two percent), settlement areas (two percent) and meadow-thicket (one percent).

Around Otty Lake itself, the shoreline buffer is dominated by woodland (48 percent) and cottages, houses and camps (35 percent) with the remainder comprised of wetland (14 percent), roads (three percent) and crop and pastureland (less than one percent). The shoreline buffer around McLaren Lake is dominated by woodland (51 percent) and wetland (49 percent). Along Jebbs Creek, the riparian zone is composed of wetland (83 percent), woodland (ten percent), settlement (five percent), crop and pastureland (one percent) and roads (one percent).

Additional statistics for the Otty Lake catchment are presented in Tables 19 to 23 and show that there has been little to no change in shoreline cover from 2008 to 2014.

5.0 Otty Lake Catchment: Stewardship and Water Resources Protection

The RVCA and its partners are working to protect and enhance environmental conditions in the Tay River Watershed. Figure 70 shows the location of all stewardship projects completed in the Otty Lake catchment.

5.1 Rural Clean Water

The Rural Clean Water Program provides technical and financial assistance to farmers and other rural landowners, to aid in the implementation of projects that protect water quality. Funding is granted to those projects that support best management practices for application in the protection and improvement of surface and ground water resources.  The program also supports climate change adaptation and low impact development projects as well as educating rural landowners about environmental stewardship of private property. Examples of supported projects include livestock exclusion fencing, controlled tile drainage, cover crops, erosion control, well related projects, and many more. For a list of eligible projects and to apply for funding, see Rural Clean Water.

In the Otty Lake catchment from 2011 to 2016, seven septic system repairs, two erosion control projects, one windbreak/buffer and one well upgrade were completed; prior to this, eight septic system repairs, eight well upgrades, three education initiatives, one manure storage facility, one milkhouse wastewater treatment project, one well decommissioning, one well replacement and one livestock fencing project had been completed. When combined, these projects are keeping 26.41 kilograms of Phosphorus out of our lakes, rivers and streams every year. Total value of all 35 projects is $325,662 with $64,241 of that amount funded through grant dollars from the RVCA.

5.2 Private Land Forestry

Forest cover and tree planting continues to be one of the most widely supported strategies to improve our environment. The many benefits of forest cover include carbon sequestration, flood mitigation and water quality improvement as well as providing wildlife habitat.

Through the RVCA's Trees for Tomorrow Program (and its predecessors), 5,800 trees were planted at two sites from 2011 to 2016; prior to this, 9,747 trees were planted at six sites. In total, 15,547 trees have been planted resulting in the reforestation of seven hectares. Total project value of all eight projects in the Otty Lake catchment is $35,523 with $25,029 of that amount coming from fundraising sources. For more information about the Program and landowner eligibility, please see the following: Tree Planting in the Rideau Valley Watershed and Trees for Tomorrow.

An additional 191 butternut trees were planted through the RVCA Butternut Recovery Program at 42 project locations, as part of efforts to introduce healthy seedlings from tolerant butternuts into various locations across Eastern Ontario.

5.3 Shoreline Naturalization

Natural shoreline buffers rich in native plants are critically important to protecting the health of our lakes, rivers and streams. Shoreline vegetation protects water quality and aquatic habitat by intercepting potentially harmful contaminants such as nutrients, pollutants and sediment, regulating water temperatures, slowing runoff and providing important fish and wildlife habitat. Natural shorelines also help improve climate change resiliency by increasing flood storage and providing protection from erosion during extreme weather events.

Though the RVCA’s Shoreline Naturalization Program, landowners (private and public property owners) have naturalized more than 2.3 km of shoreline in the Tay Watershed by planting over 10,563 native trees and shrubs at 96 sites since 2008. In the Otty Lake catchment, a total of 2,506 native trees and shrubs have been planted along 407 metres of shoreline at an average buffer width of three metres for a total project value of $19,479. A number of these projects have been undertaken in partnership with community groups. The Program has also provided the Otty Lake Association with 1,500 native tree, shrubs and wildflowers that have been distributed to property owners around Otty Lake and supported a Toronto Dominion Friends of the Environment Tree Day hosted by RVCA at the Perth Wildlife Reserve, which saw the planting of 300 trees and shrubs by local volunteers in 2016. This was followed up in 2017 by a volunteer group planting native wildflowers at the Perth Wildlife Reserve to enhance the butterfly garden for local pollinators.

5.4 Fish and Wetland Habitat Improvement

Two fish and wetland improvement projects have been completed in the Otty Lake catchment in recent years: 1) The Otty Lake Association collaborated with the Rideau Valley Conservation Authority on the Otty Lake Fish Habitat Enhancement project to improve the recreational fishery for smallmouth bass and 2) The Jebbs Creek Wetland Embayment was completed by the RVCA to enhance fish and wetland habitat along Jebbs Creek. Sixteen hundred square metres of fish habitat were created and 15 volunteers planted a mixture of 125 native trees and shrubs and trees around the new wetland feature.

5.5 Septic System Re-inspection

Septic system re-inspection is provided by the RVCA through the Mississippi Rideau Septic System Office at the request of Drummond/North Elmsley and Tay Valley Townships.

Since 2004, the service has performed 357 mandatory and voluntary septic system re-inspections on 257 properties in the Otty Lake catchment, of which, nine voluntary inspections were conducted on seven properties around McLaren and Mud Lake (with only one system needing remedial work) along with 348 mandatory re-inspectionson 250 properties around Otty Lake. Remedial/maintenance work (i.e. pump outs and baffle replacements that generally do not require a permit) was advocated for 18 of those inspections on Otty Lake, septic system replacements required at another seven properties along with more information being requested during another two inspections.

5.6 Valley, Stream, Wetland and Hazard Lands

The Otty Lake catchment covers 53 square kilometres with 3.5 square kilometres (or seven percent) of the drainage area being within the regulation limit of Ontario Regulation 174/06 (Figure 71), giving protection to wetland areas and river or stream valleys that are affected by flooding and erosion hazards.

Wetlands occupy 11 square kilometres (or 21 percent) of the catchment. Of these wetlands, two square kilometres (or 18 percent) are designated as provincially significant and included within the RVCA regulation limit. This leaves the remaining 9 sq. km (or 82 percent) of wetlands in the catchment outside the regulated area limit.

Of the 98.6 kilometres of stream in the catchment, regulation limit mapping has been plotted along 5.6 kilometres of streams (representing six percent of all streams in the catchment). Some of these regulated streams (0.6 km) flow through regulated wetlands; the remaining five kilometres of regulated streams are located outside of those wetlands. Plotting of the regulation limit on the remaining 93 kilometres (or 94 percent) of streams requires identification of flood and erosion hazards and valley systems.

Within those areas of the Otty Lake 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.

5.7 Vulnerable Drinking Water Areas

Mississippi-Rideau Source Water Protection Program has mapped the north boundary of the Otty Lake catchment as a Significant Groundwater Recharge Areas and all of the catchment as 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. There are no Well-Head protection Areas in the catchment.

The Mississippi-Rideau Source Protection Plan includes policies that focus on the protection of groundwater region-wide due to the fact that most of the region, which encompasses the Mississippi and Rideau watersheds, is considered Highly Vulnerable Aquifer. For detailed maps and policies that have been developed to protect drinking water sources, visit the Mississippi-Rideau Source Protection Region website.