1.0 Perth Catchment: Facts
1.1 General/Physical Geography
21.4 square kilometres; occupies 2.7 percent of the Tay River subwatershed; 0.5 percent of the Rideau Valley watershed.
The Perth catchment resides predominantly within the physiographic region known as the Smith Falls Limestone Plain, which is a broad flat poorly drained region underlain by thin soils, dolostone and sandstone. A veneer of glacial drift (glacial till, sand etc.) overlies the bedrock and a number of geologic faults may run through this catchment.
Drummond/North Elmsley Township: (13.2 km2; 62% of catchment)
Town of Perth (7.9 km2; 37% of catchment)
Tay Valley Township (0.2 km2; 1% of catchment)
All watercourses (including headwater streams): 35.1 km
1.2 Vulnerable Areas
Mississippi-Rideau Source Water Protection program has mapped only one very small part of this catchment as a Significant Groundwater Recharge Areas and all of the catchment as a Highly Vulnerable Aquifer (HVA). There are no Well-Head Protection Areas in the catchment.
A watershed model developed by the RVCA in 2009 was used to study the hydrologic function of wetlands in the Rideau Valley Watershed, including those found in the Perth catchment.
1.3 Conditions at a Glance
One aggregate license in the Perth catchment.
Fish Community/Thermal Regime
Warm and cool water recreational and baitfish fishery with 27 species observed in the Tay River during 2017.
Headwater Drainage Features
Multiple classifications of headwaters containing wetland, natural and undefined features along with historical modifications in the form of straightening (i.e., channelization).
Tay River: Low to high habitat complexity was identified along the Tay River in the catchment. Regions with increased habitat complexity were observed in the upper and middle reaches of the system. Dissolved oxygen conditions along the system are fairly uniform for both warm and coolwater fish species.
Land Cover Change - Perth Catchment (2008 to 2014)
Land Cover Change - Town of Perth (2008 to 2014)
Land Cover Type - Perth Catchment (2014)
Land Cover Type - Town of Perth (2014)
Shoreline Cover Type (30 m. riparian area; 2014)
||Tay River - Town
*Excludes the Tay River
Significant Natural Features
Grants Creek Provincially Significant Wetland
Perth Long Swamp Provincially Significant Wetland
Species at Risk (Elemental Occurrence)
||Species at Risk
Water Quality (WQ) for the Protection of Aquatic Life (2006 to 2017)
||@ Rogers Rd.
||@ Gore St.
||@ Craig St.
||Fair to Good
||Fair to Good
Approximately 350 operational, private water wells are to be found in the Perth catchment. Groundwater uses are mainly domestic but also include irrigation, industrial, livestock and commercial water supplies and monitoring wells.
Perth Catchment: Wetlands are reported to have covered 57 percent of the Perth catchment prior to European settlement, as compared to 32 percent (or 6.8 square kilometres) of the area in 2014. This represents a 44 percent (or 5.4 square kilometre) loss of historic wetland cover. Sixty-three percent of the remaining wetlands are regulated leaving 37 percent (or 2.5 square kilometers) unregulated.
Town of Perth: Wetlands are reported to have covered 61 percent of the Town of Perth prior to European settlement, as compared to 26 percent (or 3.2 square kilometres) of the area in 2014. This represents a 57 percent (or 4.2 square kilometre) loss of historic wetland cover. Eighty-six percent of the remaining wetlands are regulated leaving 14 percent (or 46 ha.) unregulated.
1.4 Catchment Care
The Town of Perth has an established interest and commitment to environmental stewardship (including the application of innovative, water resources best management practices) as articulated in its Official Plan (2016 Consolidation) and Strategic Plan (2015). The basic premise for community sustainability is that environmental health is critical to human beings and to the wide diversity of plant and animal species with which we co-exist. The quality of our communities and standard of living depends on the air we breathe and the water that we drink, as well as the quality of the soil in the backyards where we play and in the fields and gardens from which our food is produced. In the coming years, human prosperity will depend on the health of the natural environment and the quality of human managed spaces.
The Town of Perth's vision for development embraces the concept of sustainable development through land use and infrastructure development decisions and operational practices that integrate human needs with the natural and built environment. Land use approvals and infrastructure redevelopment decisions will include sustainable design measures for transportation, infrastructure, waste management, energy systems and will strive for the efficient use of natural resources and preservation of historic, cultural and natural heritage features. The vision intends to be adaptive to innovative design and human activities that support sustainability.
Specific examples of putting the Town of Perth's vision into practice include: GM
Town of Perth has completed a number of significant water environment projects to protect the surface water quality of the Tay River. These include: GM
- drinking water supply
- sewage treatment plant discharge
Development in, and adjacent to, the Perth Long Swamp and Grants Creek Provincially Significant Wetlands in the catchment 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.
Ten active Permits To Take Water (PTTW) are located in the southwestern part of this catchment along with one other active PTTW in its northern part, all for municipal water supply, golf course irrigation, condo heat pumps, groundwater remediation, industrial use and aggregate operations.
Several Environmental Compliance Approvals and Environmental Activity and Sector Registries were sought in this catchment for municipal drinking water systems and sewage works along with construction dewatering.
Chemical surface (in-stream) water quality collection by the RVCA since 2003 (see Section 2.1 of this report).
Fish survey and stream characterization survey by the RVCA on the Tay River in 2017 included taking measurements and recording observations on instream habitat, bank stability, other attributes and preparing a temperature profile (see Section 3 of this report).
Seven drainage feature assessments were conducted by the RVCA in 2017 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 3.4 of this report).
Classification of Perth catchment land cover types derived by the RVCA from colour aerial photography that was acquired during the spring of 2008 and 2014 (see Section 4.1 of this report).
Town of Perth?
Twenty-seven stewardship projects were completed by landowners with assistance from the RVCA (see Section 5 of this report).
2.0 Perth Catchment: Water Quality Conditions
Surface water quality conditions in the Town of Perth catchment are monitored by the Rideau Valley Conservation Authority (RVCA) Baseline Water Quality Monitoring Program. The baseline water quality program focuses on streams; data is collected for 22 parameters including nutrients (total phosphorus and total Kjeldahl nitrogen), E. coli, metals (like aluminum and copper) and additional chemical/physical parameters (such as alkalinity, chlorides, pH and total suspended solids). Figure 2 shows the locations of monitoring sites in the catchment.
Figure 2 Water quality monitoring sites on the Tay River in the Perth catchment
2.1 Tay River: Water Quality Rating
There are three monitored water quality monitored within the urban portion of the Town of Perth (Figure 2). The RVCA's water quality rating ranges from "Fair" to "Good" (Table 1) along the Tay River in the catchment, 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. "Good" indicates that only a minor degree of threat or impairment is observed and conditions rarely 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.
Data has been analyzed over the 2006-2017 period for general trends and conditions. Table 1 shows the overall rating for the monitored surface water quality sites within the catchment and Table 2 outlines the Water Quality Index (WQI) scores and their corresponding ratings. The scores at these sites are largely influenced by few high nutrient concentrations and bacterial counts. For more information on the CCME WQI, please see the Tay River Subwatershed Report.
Water Quality Index ratings for the Tay River in the Perth Catchment
Water Quality Index ratings and corresponding index scores (RVCA terminology, original WQI category names in brackets)
2.1.1 Tay River: Nutrients
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) is used as secondary indicators of nutrient loading. RVCA uses a guideline of 0.500 mg/l to assess TKN .
Tables 3 and 4 summarize average nutrient concentrations at monitored sites within the Perth catchment and show the proportion of results that meet the guidelines.
Table 3 Summary of total phosphorus results for the Perth Catchment (2006-2017).
Table 4 Summary of total Kjeldahl nitrogen results for the Perth Catchment catchment (2006-2017).
Monitoring Site TAY-04
Site TAY-04 is the most upstream site within the Town of Perth. The majority (88 percent) of samples at this site were below the TP guideline from 2006-2017 (Figures 3 and 4). The average TP concentration in the at this site was 0.021 mg/l (Table 3), the monthly average concentrations appear higher in the spring and early summer and decline into the fall (Figure 3). In August the average concentrations exceeded the guideline (Figure 3), however this seems to be due to the influence of a single elevated sample in August 2011 (Figure 4) and does not reflect typical concentrations. Overall a decrease was observed in TP concentrations over the 2006-2017 period2.
TKN concentrations show that the bulk of results (65 percent) were also below the guideline (Figure 6, Table 4). The average concentration over the 2006-2017 period was 0.499 mg/l (Table 4); monthly averages increased from April to August, with lower concentrations observed in the fall months (Figure 5). There was no significant trend found in TKN results at this site.
Monitoring Site TAY-08
Site TAY-08 is downstream of TAY-04 and within the urban portion of Perth. TP results were low, the average concentrations was 0.018 and 97 percent of samples were below the guideline (Table 3, Figure 4). Monthly TP concentrations followed a similar pattern to upstream site TAY-04, with the highest concentrations observed from May-July, average TP concentrations did not exceed the guideline in any of the monitored months (Figure 3). A declining trend in TP concentrations was also observed in the data from this site.
The majority of TKN results were below the guideline (Figure 5 and 6), 69 percent of samples were below 0.500 mg/l (TKN Guideline) with an average concentration of 0.462 mg/l (Table 4). Average monthly concentrations were comparable and also followed a similar pattern to TAY-04 (Figure 5). No significant trend was observed in the 2006-2017 TKN dataset.
Monitoring Site TAY-19
Site TAY-19 is the most downstream site within the Town of Perth, TP concentrations are comparable to both upstream sites (TAY-04 and TAY-08) previously discussed (Figure 3). Ninety-two percent of samples at this site were below the TP guideline from 2006-2017 (Figures 3 and 4), and the average TP concentration in the at this site was 0.020 mg/l (Table 3). The monthly average concentrations were also the highest from May to July and no average monthly concentration exceeded the guideline (Figure 3). A decrease was observed in TP concentrations over the 2006-2017 period.
TKN concentrations show that the bulk of results (65 percent) were also below the guideline (Figure 6, Table 4). The average concentration over the 2006-2017 period was 0.476 mg/l (Table 4). Average monthly concentrations (Figure 5) show a similar pattern to upstream sites (TAY-04 and TAY-08) with generally comparable concentrations. No trend in TKN concentrations was observed at this site.
Figure 3 Average monthly total phosphorous concentrations in the Town of Perth catchment, 2006-2017
Figure 4 Distribution of total phosphorous concentrations in the Town of Perth catchment, 2006-2017
Figure 5 Average monthly total Kjeldahl nitrogen concentrations in the Town of Perth catchment, 2006-2017
Figure 6 Distribution of total Kjeldahl nitrogen concentrations in the Town of Perth catchment, 2006-2017
Summary of Tay River Nutrients
The data collected in this catchment provides evidence that nutrient enrichment is not a significant concern in this reach of the Tay River. Overall, the consistency in TP and TKN concentrations from TAY-04 to TAY-19 support that there is little nutrient enrichment as the Tay River flows through the Town of Perth. A declining trend in TP concentrations was also noted at all sites. This provides support that cummulative changes throughout the catchment has reduced nutrient concentrations. This should be taken as a positive sign as high nutrient concentrations can help stimulate the growth of algae blooms and other aquatic vegetation in a waterbody and deplete oxygen levels as the vegetation dies off. It is important to continue using best management practices that help prevent nutrient pollution in the Tay River; measures such as maintaing/upgrading municipal infrastructure (sanitary/stormwater sewers and water works), enhancing shoreline buffers, minimizing/discontinuing the use of fertilizers and restricting livestock access in upstream agricultural areas of the catchement.
2.1.2 Tay River E. 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 5 summarizes the geometric mean for the monitored sites within the Town of Perth catchment and shows the proportion of samples that meet the E. coli guideline of 100 CFU/100 ml. The results of the geometric mean with respect to the guideline, are shown in Figures 7 and 8 respectively.
Summary of E. coli
results for the Tay River-Town of Perth Catchment, 2006-2017.
Monitoring Site TAY-04
E. coli counts at site TAY-04 indicate that counts regularly exceed the guideline of 100 CFU/100ml. Fifty percent of samples were below the guideline (Figures 7-8) and the count at the geometric mean was only 80 CFU/100ml (Table 5). Monthly E. coli counts showed that the geometric mean was highest during the warmer months and counts exceeded the guideline in June, August and September. Warm water temperatures are more favourable for bacterial growth. (Figure 7). No trend was noted in E. coli counts over the 2006-2017 period.
Monitoring Site TAY-08
Elevated E. coli counts at site downstream site TAY-08 were also common. Fifty-one percent of samples were below the guideline (Figure 8) from 2006-2017 and the count at the geometric mean was 72 CFU/100ml (Table 5). The highest counts were recorded in June and August (Figure 7). As with site TAY-09 there was no significant trend in E. coli data over the 2006-2017 period.
Monitoring Site TAY-19
E. coli counts at site TAY-19 was comparable to those upstream (TAY-04 and TAY-08). Forty-six percent of samples were below the guideline, with count of 86 CFU/100ml at the geometric mean (Table 5, Figure 8). Monthly E. coli counts were aobve the guideline from June-September (Figure 7). As with upstream sites, no trend was noted in E. coli counts over the 2006-2017 period.
Figure 7 Geometric mean of E. coli results in the Town of Perth catchment, 2006-2017
Figure 8 Distribution of E. coli counts in the Town of Perth catchment, 2006-2017.
Summary of Tay River Bacterial Contamination
Given the frequency of samples that exceed the guidelines and counts approaching the guideline at all three sites, there is evidence that at times bacterial pollution is a concern within this reach of the Tay River. The data is comparable between all three sites thus does not provide sufficient information to pinpoint possible sources of pollution. Minimizing runoff from infrastructure and roadways should be a priority in this catchment, such as ongoing efforts to improve storm water management within developed areas. Best management practices such as maintaining/enhancing municipal infrastructure, enhancing shoreline buffers, limiting livestock access and minimizing runoff in both agricultural and developed areas can help to protect this reach of the Tay River into the future.
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.
2Trends in the data were assessed using the Mann-Kendall trend test and Sens slope statistic.
3 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 Perth Catchment: Riparian Conditions
The RVCA Stream Characterization Program surveyed 4.6 kilometres (46 sections) of the Tay River in July 2017 within the Perth catchment.
In 2017 the Tay River subwatershed experienced high water levels along the Tay River and its tributaries. After moving from two years of drought conditions in 2015 and 2016 heavy rains throughout the year made 2017 the wettest year in recorded history. Precipitation was close to normal in the Tay River watershed in January, 2017. Most of the rest of the year, however, the area got much more than normal. For the year the total precipitation was over 130% of normal. The spring snowmelt peak flow was an above average 57 cubic metres per second (cms) in Perth on April 6. Flows receded there until more than 100 mm of rain fell over the first week of May causing a peak flow on May 7 of 71 cms, a flow not previously reached in the 24 years of records. Flows increased once again at the end of October as a result of another heavy rainfall totaling 124 mm over nine days that caused a considerable delay in construction of the rocky ramp replacement for the Haggart Island Dam.
Flooding along the Tay River in Stewart Park during the spring of 2017
3.1 Perth Catchment Overbank Zone
3.1.1 Riparian Land Cover 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 mitigates 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 9 demonstrates the buffer conditions of the left and right banks separately. The Tay River had a buffer of greater than 30 meters along 65 percent of the left bank and 46 percent of the right bank.
Figure 9 Riparian Buffer Evaluation along the Tay River in the Perth catchment
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 10). The riparian buffer zone along the Tay River was found to be dominated by forest, scrubland, wetlands and meadow conditions. There were several areas that had altered riparian zone conditions along the Tay River. These areas included shoreline modifications in the form of armour stone, wooden retaining walls, gabion baskets, concrete and rip rap. Modifications also included a number of road crossings and areas with reduced natural vegetated buffer conditions. Opportunities for shoreline buffer enhancements along the Tay River in the Town of Perth catchment should be explored and implemented where possible.
Figure 10 Riparian buffer alterations along Tay River in the Perth catchment
3.1.3 Adjacent Land Use
The RVCA’s Stream Characterization Program identifies nine different land uses along the Tay River in the Town of Perth (Figure 11). 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. Scrubland habitat was dominant at 91 percent; forest and wetlands were found along 61 percent of the surveyed sections and 11 percent meadow habitat was present along the Tay River. The remaining land use consisted of residential, recreational, industrial/commercial and infrastructure in the form of road crossings.
Figure 11 Land Use along the Tay River in the Perth catchment
3.2 Perth Catchment 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 the Tay River had no erosion observed along the majority of surveyed sections with a few small sections having low levels of erosion (Figure 12).
Figure 12 Erosion levels along the Tay River in the Perth catchment
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 13 shows that the Tay River had no observed undercut banks along the majority of the system, however there were several sections in the lower reach with low levels of undercut banks.
Figure 13 Undercut stream banks along the Tay River in the Perth catchment
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 1m above the water surface. Figure 14 shows low levels of stream shading along the Tay River. Stream shading conditions were fairly uniform along the Tay River ranging from no overhead canopy cover to low levels. There were two areas along the Tay River that reached moderate levels of stream shading.
Figure 14 Stream shading along the Tay River in the Perth catchment
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 and forested lakeshores having been altered as a result wood-based physical structure in many waterbodies has been reduced. It is important to restore this essential habitat to aquatic ecosystems.
- 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
- 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 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
- 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 15 shows that the majority of the Tay River had low levels of instream wood structure along the system. There were several stream survey sections in the upper reach which were characterized as having moderate levels of instream wood structure in the form of branches and trees along the system.
Figure 15 Instream wood structure along the Tay River in the Perth catchment
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 provides a food source, nutrients and shade which helps to moderate instream water temperatures. Figure 16 shows the system is variable with no overhanging branches and trees to areas that have high levels of overhanging wood structure along the Tay River.
Figure 16 Overhanging wood structure along the Tay River in the Perth catchment
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 17 shows fifteen percent of the Tay River remains “unaltered” with no anthropogenic alterations. Forty six percent of the Tay River was classified as natural with minor anthropogenic changes. Thirty five percent of survey sections were classified as being altered and four percent was classified as highly altered. These areas consisted of sections with shoreline modifications and road crossings.
Figure 17 Anthropogenic alterations along the Tay River in the Perth catchment
3.3 Perth Catchment Instream Aquatic Habitat
3.3.1 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 wood structure.
Low to high habitat complexity was identified for the Tay River in the Town of Perth catchment (Figure 18). Regions with increased habitat complexity were observed in the upper and middle reaches of the system within the catchment.
Figure 18 Habitat complexity along the Tay River in the Perth 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. Substrate conditions were highly diverse along the Tay River with all substrate types being recorded at various locations along the system (Figure 19). Figure 20 shows the dominant substrate type observed for each section surveyed along the Tay River.
Figure 19 Instream substrate along the Tay River in the Perth catchment
shows the dominant substrate type along the Tay River in the Perth catchment
3.3.4 Instream Morphology
Pools and riffles are important habitat features for aquatic life. Riffles are fast flowing areas characterized 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 characterized 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 center of the channel. Figure 21 shows that the Tay River is somewhat uniform; 100 percent of sections recorded runs, 57 percent pools and 7 percent riffles. Figure 22 shows where the limited riffle habitat areas were observed along the Tay River.
Figure 21 Instream morphology along the Tay River in the Perth catchment
Figure 22 Instream riffle habitat along the Tay River in the Perth catchment
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
- Stabilizing 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. Submerged plants were dominant in this reach of the Tay River and were observed at 100 percent of surveyed sections. Broad leaved emergents were observed in 85 percent of sections, 78 percent floating plants, 76 percent narrow leaved emergents, 72 percent of sections contained algae, 63 percent free floating, while robust emergents were present in 54 percent of the survey sections. Figure 23 depicts the plant community structure for the Tay River. Figure 24 shows the dominant vegetation type observed for each section surveyed along the Tay River in the Perth catchment.
Figure 23 Vegetation type along the Tay River in the Perth catchment
Figure 24 Dominant vegetation type along the Tay River in the Perth 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 25 demonstrates that the Tay River had normal to common levels of vegetation recorded at 89 and 57 percent of stream surveys. Extensive levels of vegetation were observed in 59 percent of the surveyed sections, while twenty eight percent of sections had no vegetation in areas that were dominated by bedrock substrate conditions.
Figure 25 Instream vegetation abundance along the Tay River in the Perth catchment
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. Eighty nine percent of the sections surveyed along the Tay River in the Perth catchment had invasive species. The invasive species observed were common/glossy buckthorn, banded mystery snail, bull thistle, curly leafed pondweed, dog strangling vine, Eurasian milfoil, European frogbit, Himalayan balsam, honey suckle, Manitoba maple, wild parsnip and purple loosestrife. 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 26).
Figure 26 Invasive species abundance along the Tay River in the Perth catchment
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.
22.214.171.124 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 27 shows that the dissolved oxygen in Tay River supports warmwater and coolwater biota along the system. The average dissolved oxygen level observed within the Perth catchment was 7.0mg/L which meets the recommended level for warm and cool water biota.
Figure 27 Dissolved oxygen ranges along the Tay River in the Perth catchment
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 Tay River was 198.3 µs/cm. Figure 28 shows the conductivity readings for the Tay River in the Perth catchment.
Figure 28 Specific conductivity ranges along the Tay River in the Perth catchment
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 along the Tay River were 7.4 thereby meeting the provincial standard (Figure 29).
Figure 29 pH ranges along the Tay River in the Perth catchment
126.96.36.199 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 stabilize 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 summarized into 6 classes:
Dissolved oxygen conditions for the Tay River were fairly uniform along the system for both warm and coolwater species (Figure 30).
Figure 30 A bivariate assessment of dissolved oxygen concentration (mg/L) and saturation (%) along the Tay River in the Perth catchment
188.8.131.52 Specific Conductivity Assessment
Specific conductivity (SPC) is a standardized 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 summarize 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 in the middle reaches of the Tay River, however there were elevated areas in the upper and lower reaches (Figure 31). Two sections had high conductivity levels observed in the lower reach and several sections had moderate levels observed also in the lower reach.
Figure 31 Relative specific conductivity levels along the Tay River in the Perth catchment
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 32 shows where the thermal sampling sites were located on the Tay River in the Perth catchment. Analysis of the data collected indicates that the Tay River is classified as a warm water system (Figure 33).
Figure 32 Temperature logger locations along the Tay River in the Perth catchment
Figure 33 Temperature logger data for the sites along the Tay River in the Perth catchment
Each point on the graph represents a temperature that meets the following criteria:
- Sampling dates between July 1st and September 7th
- Sampling date is preceded by two consecutive days above 24.5 °C, with no rain
- Water temperatures are collected at 4pm
- Air temperature is recorded as the max temperature for that day
Groundwater discharge areas can influence stream temperature, contribute nutrients, and provide important stream habitat for fish and other biota. During stream surveys, indicators of groundwater discharge are noted when observed. Indicators include: springs/seeps, watercress, iron staining, significant temperature change and rainbow mineral film. Figure 34 shows areas where one or more of the above groundwater indicators were observed during stream surveys and headwater assessments.
Figure 34 Groundwater indicators observed in the Perth catchment
3.3.11 Fish Community
The Perth catchment is classified as a mixed community of warm and cool water recreational and baitfish fishery with 27 species observed (Figure 35).
Figure 35 Fish community sampling observations in the Perth catchment
Table 6 contains a list of fish species observed in the Perth catcmment.
Fish species observed in the Perth catchment
RVCA staff measuring and weighing fish while sampling on the Tay River in the Perth catchment
A fyke net set along the Tay River in the Perth catchment in July of 2017
3.3.12 Migratory Obstructions
It is important to know locations of migratory obstructions because these can prevent fish from accessing important spawning and rearing habitat. Migratory obstructions can be natural or manmade, and they can be permanent or seasonal. Figure 36 shows that the Perth catchment had one weir and one man made dam on the Tay River at the time of the survey in 2017.
Figure 36 Migratory obstructions in the Perth catchment
A weir located on the Tay River in the Perth catchment
3.4 Headwater Drainage Feature Assessment
3.4.1 Headwaters Sampling Locations
The RVCA Stream Characterization program assessed Headwater Drainage Features for the Tay River 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 7 sites at road crossings in the Perth catchment area (Figure 37).
Figure 37 Locations of the headwater sampling sites in the Perth catchment
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 Perth catchment are highly variable. Figure 38 shows the feature type of the primary feature at the sampling locations.
Figure 38 Headwater feature types in the Perth catchment
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 39 shows the observed flow condition at the sampling locations in the Perth catchment.
Figure 39 Headwater feature flow conditions in the Perth catchment
A spring photo of the headwater sample site in the Perth catchment located on Hands Road
A summer photo of the headwater sample site in the Perth catchment located on Hands Road
3.4.4 Feature Channel Modifications
Channel modifications were assessed at each headwater drainage feature sampling location. Modifications include channelization, dredging, hardening and realignments. The Perth catchment area had four features with no channel modifications observed and three features as having been historically dredged or channelized. Figure 40 shows the channel modifications observed at the sampling locations for the Perth catchment.
Figure 40 Headwater feature channel modifications in the Perth catchment
3.4.5 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 wildlife habitat. The following classifications are evaluated no vegetation, lawn, wetland, meadow, scrubland and forest. Figure 41 depicts the dominant vegetation observed at the sampled headwater sites in the Perth catchment.
Figure 41 Headwater feature vegetation types in the Perth 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. Figure 42 depicts the type of riparian vegetation observed at the sampled headwater sites in the Perth catchment.
Figure 42 Headwater feature riparian vegetation types in the Perth 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. Sediment deposition ranged from none to substantial for the headwater sites sampled in the Perth catchment area. Figure 43 depicts the degree of sediment deposition observed at the sampled headwater sites in the Perth catchment. Sediment deposition conditions ranged from no sediment deposition to substantial.
Figure 43 Headwater feature sediment deposition in the Perth 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 Structure 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. Figure 44 shows the feature roughness conditions at the sampling locations in the Perth catchment were highly variable ranging from minimal to extreme.
Figure 44 Headwater feature roughness in the Perth catchment
4.0 Perth Catchment: Land Cover
Land cover and any change in coverage that has occurred over a six-year period is summarised for the Perth 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 20 cm DRAPE ortho-imagery at a 1:4000 scale and details the surrounding landscape using 10 land cover classes.
4.1 Perth Catchment Land Cover/Change
As shown in Table 7 and in Figure 1 (found in the Introduction section of this report), the dominant land cover type across the Perth catchment in 2014 is wetland followed by crop and pastureland and settlement.
Land cover in the Perth catchment (2008 vs. 2014)
* Does not include treed swamps ** Includes treed swamps
From 2008 to 2014, there was an overall change of 16 hectares (from one land cover class to another). Most of the change in the Perth catchment is a result of the conversion of crop and pastureland to settlement and woodland to crop and pastureland (Figure 45).
Figure 45 Land cover change in the Perth catchment (2014)
Table 8 provides a detailed breakdown of all land cover change that has taken place in the Perth catchment between 2008 and 2014.
Land cover change in the Perth catchment (2008 to 2014)
4.1.1 Town of Perth Land Cover/Change
As shown in Figure 46 and in Table 9, the dominant land cover type of all lands within the municipal boundary of the Town of Perth in 2014 is settlement followed by wetland (Grants Creek/Perth Long Swamp PSW's).
46 Land cover in the Town of Perth (2014)
Land cover in the Town of Perth (2008 vs. 2014)
* *Does not include treed swamps ** Includes treed swamps
From 2008 to 2014, there was an overall change of nine hectares from one land cover class to another, which can be attributed to the conversion of crop and pasture, woodland and meadow-thicket to new development (e.g., commercial and residential). Figure 47 shows the areas within the Town of Perth where land cover has changed over the six years.
Figure 47 Land cover change in the Town of Perth (2008 vs. 2014)
Table 10 provides a detailed breakdown of land cover change that has occurred in the Town of Perth between 2008 and 2014.
Land cover change in the Town of Perth (2008 vs. 2014)
4.2 Woodland Cover
In the Environment Canada Guideline (Third Edition) entitled “How Much Habitat Is Enough?” 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 Rideau subwatershed and elsewhere in the Rideau Valley watershed). These ecological features are in addition to other influences which forests have on water quality and stream hydrology including reducing soil erosion, producing oxygen, storing carbon along with many other ecological services that are essential not only for wildlife but for human well-being.
The Guideline also notes that forests provide a great many habitat niches that are in turn occupied by a great diversity of plant and animal species. They provide food, water and shelter for these species - whether they are breeding and resident locally or using forest cover to help them move across the landscape. This diversity of species includes many that are considered to be species at risk. Furthermore, from a wildlife perspective, there is increasing evidence that the total forest cover in a given area is a major predictor of the persistence and size of bird populations, and it is possible or perhaps likely that this pattern extends to other flora and fauna groups. The overall effect of a decrease in forest cover on birds in fragmented landscapes is that certain species disappear and many of the remaining ones become rare, or fail to reproduce, while species adapted to more open and successional habitats, as well as those that are more tolerant to human-induced disturbances in general, are able to persist and in some cases thrive. Species with 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.
Perth Catchment Woodland Cover
As shown in Figure 48, 14 percent of the Perth catchment contains 268 hectares of upland forest and 43 hectares of lowland forest (treed swamps) versus the 47 percent of woodland cover in the Tay River subwatershed. This is less than the 30 percent of forest cover that is identified as the minimum threshold required to sustain forest birds according to the Guideline and which may only support less than one half of potential species richness and marginally healthy aquatic systems. When forest cover drops below 30 percent, forest birds tend to disappear as breeders across the landscape.
Figure 48 Woodland cover and interior forest in the Perth catchment (2014)
Town of Perth Woodland Cover
As shown in Figure 49, 13 percent of the Town of Perth contains 147 hectares of upland forest and 9 hectares of lowland forest (treed swamps) versus the 47 percent of woodland cover in the Tay River subwatershed. This is less than the 30 percent of forest cover that is identified as the minimum threshold required to sustain forest birds according to the Guideline and which may only support less than one half of potential species richness and marginally healthy aquatic systems. When forest cover drops below 30 percent, forest birds tend to disappear as breeders across the landscape.
Figure 49 Woodland cover and interior forest in the Town of Perth (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 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.
Perth Catchment Woodland (Patch) Size
In the Perth catchment (in 2014), sixty-three (62 percent) of the 102 woodland patches are very small, being less than one hectare in size. Another 35 (34 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 four (four percent of) woodland patches range between 22 and 56 hectares in size and may support a few area-sensitive species along with some edge intolerant species, but will be dominated by edge tolerant species.
No patch exceeds the 100 plus hectare size needed to support most forest dependent, area sensitive birds and which are large enough to support approximately 60 percent of edge-intolerant species. No patch tops 200 hectares, which according to the Environment Canada Guideline will support 80 percent of edge-intolerant forest bird species (including most area sensitive species) that prefer interior forest habitat conditions.
Table 11 presents a comparison of woodland patch size in 2008 and 2014 along with any changes that have occurred over that time in the Perth catchment. A decrease (of six hectares) has been observed in the overall woodland patch area between the two reporting periods with most change occurring in the 1 to 20 hectare woodland patch size class range.
Woodland patches in the Perth catchment (2008 and 2014)
*Includes treed swamps
Town of Perth Woodland (Patch) Size
In the Town of Perth (in 2014), thirty-eight (57 percent) of the 100 woodland patches are very small, being less than one hectare in size. Another 27 (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 two (three percent of) woodland patches are 24 and 25 hectares in size and may support a few area-sensitive species along with some edge intolerant species, but will be dominated by edge tolerant species.
No patch exceeds the 100 plus hectare size needed to support most forest dependent, area sensitive birds and which are large enough to support approximately 60 percent of edge-intolerant species. No patch tops 200 hectares, which according to the Environment Canada Guideline will support 80 percent of edge-intolerant forest bird species (including most area sensitive species) that prefer interior forest habitat conditions.
Table 12 presents a comparison of woodland patch size in 2008 and 2014 along with any changes that have occurred over that time in the Town of Perth. A decrease (of two hectares) has been observed in the overall woodland patch area between the two reporting periods, with all change occurring in the 1 to 20 hectare woodland patch size class range.
Woodland patches in the Town of Perth (2008 and 2014)
*Includes treed swamps
4.2.2 Woodland (Forest) Interior Habitat
The forest interior is habitat deep within woodlands. It is a sheltered, secluded environment away from the influence of forest edges and open habitats. Some people call it the “core” or the “heart” of a woodland. The presence of forest interior is a good sign of woodland health, and is directly related to the woodland’s size and shape. Large woodlands with round or square outlines have the greatest amount of forest interior. Small, narrow woodlands may have no forest interior conditions at all. Forest interior habitat is a remnant natural environment, reminiscent of the extensive, continuous forests of the past. This increasingly rare forest habitat is now a refuge for certain forest-dependent wildlife; they simply must have it to survive and thrive in a fragmented forest landscape (Conserving the Forest Interior. Ontario Extension Notes, 2000).
The Natural Heritage Reference Manual states that woodland interior habitat is usually defined as habitat more than 100 metres from the edge of the woodland and provides for relative seclusion from outside influences along with a moister, more sheltered and productive forest habitat for certain area sensitive species. Woodlands with interior habitat have centres that are more clearly buffered against the edge effects of agricultural activities or more harmful urban activities than those without.
Perth Catchment Woodland (Forest) Interior Habitat
In the Perth catchment (in 2014), the 102 woodland patches contain four forest interior patches (Figure 49) that occupy less than one percent (14 hectares) 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.
All four patches have less than 10 hectares of interior forest, one of which has a small area of interior forest habitat less than one hectare in size. Between 2008 and 2014, there was no change in the area of interior forest habitat in the Perth catchment (Table 13).
Woodland interior in the Perth catchment (2008 and 2014)
Town of Perth Woodland (Forest) Interior Habitat
In the Town of Perth catchment (in 2014), the 100 woodland patches contain five forest interior patches (Figure 49) that occupy less than one percent (three hectares) 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.
Between 2008 and 2014, there was no change in the area of interior forest habitat in the catchment (Table 14).
Woodland interior in the Town of Perth (2008 and 2014)
4.3 Wetland Cover
Wetlands are habitats forming the interface between aquatic and terrestrial systems. They are among the most productive and biologically diverse habitats on the planet. By the 1980s, according to the Natural Heritage Reference Manual, 68 percent of the original wetlands south of the Precambrian Shield in Ontario had been lost through encroachment, land clearance, drainage and filling.
Wetlands perform a number of important ecological and hydrological functions and provide an array of social and economic benefits that society values. Maintaining wetland cover in a watershed provides many ecological, economic, hydrological and social benefits that are listed in the Reference Manual and which may include:
- contributing to the stabilization of shorelines and to the reduction of erosion damage through the mitigation of water flow and soil binding by plant roots
- mitigating surface water flow by storing water during periods of peak flow (such as spring snowmelt and heavy rainfall events) and releasing water during periods of low flow (this mitigation of water flow also contributes to a reduction of flood damage)
- contributing to an improved water quality through the trapping of sediments, the removal and/or retention of excess nutrients, the immobilization and/or degradation of contaminants and the removal of bacteria
- providing renewable harvesting of timber, fuel wood, fish, wildlife and wild rice
- contributing to a stable, long-term water supply in areas of groundwater recharge and discharge
- providing a high diversity of habitats that support a wide variety of plants and animals
- acting as “carbon sinks” making a significant contribution to carbon storage
- providing opportunities for recreation, education, research and tourism
Historically, the overall wetland coverage within the Great Lakes basin exceeded 10 percent, but there was significant variability among watersheds and jurisdictions, as stated in the Environment Canada Guideline. In the Rideau Valley Watershed, it has been estimated that pre-settlement wetland cover averaged 35 percent using information provided by Ducks Unlimited Canada (2010) versus the 21 percent of wetland cover existing in 2014 derived from DRAPE imagery analysis.
Perth Catchment Wetland Cover
This decline in wetland cover is also evident in the Perth catchment (as seen in Figure 50 and summarized in Table 15), where wetland was reported to cover 57 percent of the area prior to settlement, as compared to 32 percent in 2014. This represents a 44 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 50 Wetland cover in the Perth catchment (Historic to 2014)
Wetland cover in the Perth catchment (Historic to 2014)
Town of Perth Wetland Cover
The decline in wetland cover, which has occurred both in the Perth catchment and in the larger Rideau Valley Watershed, is also evident in the Town of Perth (as seen in Figure 51 and summarised in Table 16), where wetland was reported to cover 61 percent of the area prior to settlement, as compared to 26 percent in 2014. This represents a 57 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 for residents of the Town of Perth and surrounding communities.
Wetland cover in the Town of Perth (Historic to 2014)
Wetland cover in the Town of Perth (Historic to 2014)
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.
Perth Catchment Shoreline Cover
Figure 52 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 Tay River and its tributaries in the Perth catchment.
Natural and other riparian land cover in the Perth catchment (2014)
This analysis shows that the riparian zone in the Perth catchment is composed of wetland (53 percent), crop and pastureland (13 percent), settlement (12 percent), woodland (11 percent), transportation routes (six percent), meadow-thicket (four percent) and aggregate extraction (one percent). Along the many watercourses (including headwater streams) flowing into the Tay River, the riparian buffer is composed of wetland (62 percent), crop and pastureland (16 percent), woodland (eight percent), settlement areas (six percent), transportation routes (five percent), meadow-thicket (two percent) and aggregate extraction (one percent). Along the Tay River within the Perth catchment, the riparian zone is composed of settlement areas (36 percent), woodland (24 percent), wetland (21 percent), transportation routes (13 percent), meadow-thicket (six percent) and crop and pastureland (less than one percent).
Riparian cover statistics for the Perth catchment are presented in Tables 17, 18, and 19 and show that there has been very little to no change in shoreline cover from 2008 to 2014.
Riparian land cover in the Perth catchment (2008 vs. 2014)
Riparian land cover along the Tay River in the Perth catchment (2008 vs. 2014)
Riparian land cover along streams in the Perth catchment (2008 vs. 2014)
Town of Perth Shoreline Cover
Figure 53 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 Tay River and its tributaries in the Town of Perth.
Figure 53 Natural and other riparian land cover in the Town of Perth (2014)
Along the Tay River and Canal within the municipal limits of the Town of Perth, the riparian zone is composed of settlement areas (36 percent), woodland (23 percent), wetland (19 percent), transportation routes (13 percent), meadow-thicket (seven percent) and crop and pastureland (one percent).
Additional statistics for the Tay River and Canal in the Town of Perth are presented in Table 20 and show that there has been very little change in shoreline cover from 2008 to 2014.
Riparian land cover along the Tay River and Canal in the Town of Perth (2008 vs. 2014)
6.0 Perth Catchment: Accomplishments
Achievements and activities noted by the Friends of the Tay Watershed Association (FoTW) are indicated by an asterisk.*
4.6 kilometres of the Tay River in the catchment have been surveyed and seven headwaters sites are sampled once every six years by the RVCA using the Ontario Stream Assessment Protocol.
The report "Fish Habitat of the Tay River Watershed: Existing Conditions and Opportunities for Enhancement" was prepared in 2002 by MNR, RVCA, Parks Canada and DFO. A number of specific fish habitat enhancement projects are identified in the report to improve the fishery along the Tay River (see pp. 86-92). One such project identified along the reach of the Tay River in the Town of Perth includes the refurbishment of the two Haggart Island dams. Both of these structures have now been replaced with a rocky ramp on the Little Tay River (in 2015) and another one on the Tay River (in 2017)(see section 5.4 of this report).
The Friends of the Tay Watershed and RVCA developed the Wendy Laut Ribbon of Life demonstration area in Last Duel Park alongside the Tay River. Recently, the Perth Horticultural Society has updated the area.*
4554 native trees and shrubs have been planted along 764 metres of shoreline at various locations along the Tay River in the Town of Perth with services provided by the RVCA Shoreline Naturalization Program.
The Town of Perth wastewater treatment facility is located on the south side of the Tay River, adjacent to the Tay Marsh. The outflow from the Perth sewage lagoons has impacted water downstream for decades. Outflow quality has, on the average, been within provincial limits, but inevitably has had an impact on the Tay Marsh and is one of (many) sources encouraging excessive vegetation growth in the wetland, which damages its fish and wildlife habitat. In response to concerns raised about the impact of the Town of Perth sewage lagoons on the Tay River and Tay Marsh, the Town has taken action over the years to reduce its effect on surface water quality in the system, which, from cursory observation has been beneficial, and more recently enhanced with an innovative phosphorus reduction system.*
Further to this observation, it is stated in the Infrastructure Master Plan for the Western Annex in the Town of Perth (Jp2g Consultants, Jan.2019) that, since 2007, the Town has undergone an intensive wet weather flow reduction program, including sealing and repair work of sewers, elimination of combined sewers and sealing and elevating manholes. These efforts have successfully reduced average inflows to the lagoon and the wet weather program is continuing with further improvements expected.
In collaboration with the Town of Perth, the Friends of the Tay Watershed sampled stormwater during the first flush of a rain event on 29 September 2015. Thirty samples were taken during this single event from six access points along the lower five blocks of the Town of Perth’s Wilson Street Stormwater Drain, from Leslie Street to Herriott Street, adjacent to the outfall into the Little Tay River. Samples were analysed for E coli, Fecal Strep, Total Suspended Solids, Phosphates, Total Kjeldahl Nitrogen, and Sodium. Additionally, temperature at capture, pH, Colour, Alkalinity and Turbidity were measured and recorded by Town of Perth Water Treatment Plant staff. Further information has been gathered about the extent of contaminant levels in local storm water in the Wilson Street Stormwater Drain. The sources of contamination appear to be from the washing of large, more heavily trafficked paved surfaces, such as parking lots and major roads. No particular trends were displayed along the length of the Drain studied. Besides indicating the sources and extent of E. coli content in the system, this assessment raises additional concerns needing further study, including the consequences of river contamination by the nutrients and suspended solids discharged with urban storm water.*
The Friends of the Tay Watershed sampled three sites along the Tay River in 2013, all popular swimming spots in Perth. All showed high levels of E. coli after rain but not before; likely due to untreated stormwater being channelled quickly into the Tay River. Before rain event E. coli levels were higher even though temperatures were a little lower, possibly due to more and heavier rains resulting in near-flooding conditions along the Tay River and strong water currents. In mid-September 2014, three more sites were sampled by FoTW along the Tay River in Perth. Ten samples were taken in close proximity to two storm sewer outflows. Five more samples were taken farther downstream in Perth, but not near any stormwater outflows. All were taken within an hour of the start of light rain and the arithmetically averaged geometric mean from the test samples was 993 units of E. coli per 100 ml of water. All of the previously elevated E. coli counts had returned to “normal” levels close to or within the safe-to-swim limit of 100 units of E. coli per 100 ml. of water, 24 hours after the rain had stopped, with an average geometric mean of 83 E. coli per 100 ml. of water. All samples taken near the outflows were much higher than those taken some distance from any outflow. These findings complete the FoTW testing picture that shows consistently low and swimmable levels of E. coli before rain events and also within 24 hours of a rain event, but that levels of E. coli are, however, consistently higher even after a light rain and dangerously high near storm sewer outflows.*
The 2011 Perth Catchment Report and water testing records for the Town of Perth have been a major help in monitoring and determining activity in this sector. As in any urban area, Perth has an impact on the water quality in its Tay River. The Town has generally taken this seriously and attempted to mitigate it, with innovative and environmentally sensitive approaches. Both RVCA and the Friends of the Tay Watershed Association have presumably been instrumental in pointing out need and have cooperated with the Town of Perth in determining and following up actions.*
Three stream monitoring sites on the Tay River in the Town of Perth are sampled yearly by the RVCA for 22 parameters at each location, six times a year, to assess surface chemistry water quality conditions.
Eighteen Rural Clean Water Program projects were completed by the RVCA Rural Clean Water Program.
Watershed Planning and Management
The Tay Watershed Management Plan (2002) brought together a diverse group of watershed stakeholders to exchange information and opinions on the challenges facing the watershed. This forum focused the community on the need for managing the Tay Watershed, requiring positive cooperation amongst a range of stakeholders and helped develop a foundation of data and information on the watershed and resources against which later developments and trends are being measured and decisions are being made.
The Plan also led to the formation of the Friends of the Tay Watershed Association, who have been instrumental in implementing 20 of 24 management plan recommendations. In the opinion of the Association, one of the most significant measures of success for the water protection activities carried out in the Tay watershed is that there has never been a serious environmental pollution incident that threatened the area’s drinking water or its recreational waterbodies. To this day, the Friends of the Tay Watershed remain committed to preserving and enhancing the health of the Tay River watershed through their work, including:
- Building an understanding of the Tay River and promoting the Tay Canal and need for its care. RVCA catchment reports have played a major role in this by documenting it and its needs.
- Increasing awareness of the Tay Wildlife Reserve, helping promote the Butterfly Garden at the Reserve (in the 2009 Anniversary celebration), researching the Canal’s history and documenting it in an interpretive panel at the Reserve, and working with RVCA in placing a canoe/boat dock at the Reserve. The launch of the Tay Canal tour boat, by private individuals, was done to provide a means of bringing residents to the Tay River and Canal, and educating them about it.
- Bursaries to high school students proceeding to an environment degree as well as continuing post-secondary students.
- Development of interpretive panels for Source Water Protection (eg. Glen Tay catchment area) and the Tay River viewpoint (along the Tay Trail).
- Environmental Awards.
- Outreach to children and schools as well as the public through initiatives such as the Perth Maple Fest, the Stewart Park Festival and the Association's annual Tay Watershed Discovery Day that increases awareness of the importance of the Tay River and area lakes to the health of the Tay Watershed.
- Submissions to government on regulatory reviews (eg. Climate change action; Conservation Authority Act) and the Rideau Canal Management Plan.
- Support to other environmental, watershed organisations (e.g., Lake Links, Lake Networking Group).