Carruthers Creek Watershed Plan: Headwater Drainage Features Characterization

Transcription

1 Carruthers Creek Watershed Plan: Headwater Drainage Features Characterization Prepared for: Region of Durham 8/1/2017

2 This study was funded by the Region of Durham. Prepared by: Jan Moryk, Project Manager, Aquatic Monitoring & Analysis; Laura Del Giudice, Manager, Watershed Planning & Reporting Reviewed by: Scott Jarvie, Associate Director, Environmental Monitoring and Data Management Gary Bowen, Watershed Specialist Duffins Carruthers and Great Lakes Advisor Toronto and Region Conservation Authority, 2017 For more information:

3 Foreword The Region of Durham recognises watershed plans as an effective tool to inform the management of Durham s water resources, natural heritage, and natural hazards, such as flooding. In 2015, the Region retained the Toronto and Region Conservation Authority (TRCA) to update the watershed plan for Carruthers Creek. This four year study will build upon the goals, objectives, and management recommendations established in the 2003 Watershed Plan for Duffins Creek and Carruthers Creek, thereby ensuring a continuum of management efforts to achieve the desired ecological and sustainability objectives for the watershed. The following report is one of a series of technical reports that were prepared at the end of the first phase of the watershed plan development process to characterize the existing conditions of the watershed. Information contained in these reports will provide the knowledge base necessary to develop management recommendations during Phase 2. The reports were subject to an independent peer review process. The final integrated watershed plan will be completed by the end of Phase 2.

4 Table of Contents 1. Introduction Carruthers Creek Watershed Plan Study Area Why Study Headwater Drainage Features? 4 2. Methods Study Design Headwater Drainage Features Characterization Methodology Hydrology Classification Methodology Riparian Classification Methodology Fish and Terrestrial Data Collection Methodology Classification Results Hydrology Classification Results Riparian Classification Results Fish and Terrestrial Habitat Data Results Conclusions References 29

5 List of Figures Figure 1: Carruthers Creek Watershed Plan Study Area as of Figure 2: Carruthers Creek watershed plan study area and headwater drainage features characterization area... 5 Figure 3: Study area and ArcHydro drainage line analysis results for Carruthers Creek watershed... 8 Figure 4: Headwater drainage feature sampling locations. Due to the scale of the map, proximal site visit locations may appear to occur in slightly different locations or indicate different findings, however these occurrences actually represent different features Figure 5: Ecological Land Classification (ELC) mapping for study area...13 Figure 6: TRCA s natural cover layer for study area Figure 7: Proportion of HDF by feature type...17 Figure 8: Location of HDF by feature type. Due to the scale of the map, it may appear that the main Carruthers Creek is tile drained, however this actually represents where the tile draining the adjacent agricultural land outlets to the main creek Figure 9: Proportion of HDF by their assigned hydrology classification Figure 10: Location of HDF and their hydrological classification. Point data represent the flow observations at that location. Line data represent the extrapolated hydrological classification for the reach according to directions provided in the guideline Figure 11: Proportion of HDF by their assigned riparian classification Figure 12: Proportion of HDF feature types by riparian vegetation type Figure 13: Location of HDF and their assigned riparian classification Figure 14: HDF sampling locations where fish and/or amphibians were observed. Refer to Table 5 for species observations at each sampling location List of Tables Table 1: Headwater drainage feature site assessment dates. Both the assessment period recommended in the HDF Guidelines and the actual field site visit dates are indicated Table 2: Proportion of feature types classified by hydrology function Table 3: Proportion of HDF by their assigned riparian classification and vegetation type Table 4: Proportion of HDF feature types by riparian classification Table 5: Amphibian species and fish records found in proximity to HDF sampling locations... 26

6 1. Introduction 1.1 Carruthers Creek Watershed Plan Study Area Carruthers Creek is a relatively small watershed with a drainage area of approximately 3,748 hectares (9,261 acres), ranging from two to three kilometres in width, and only 18 kilometres in length (Figure 1). It is the easternmost watershed in TRCA's jurisdiction and is located entirely in the Region of Durham. At the request of the Region of Durham, a small section of lands in East Duffins Creek subwatershed, which are immediately adjacent to Carruthers Creek watershed and outside of the provincial Greenbelt, were included in the study area. The watershed occurs within the South Slope and Glacial Lake Iroquois physiographic regions, south of the Oak Ridges Moraine. Topographically, most of Carruthers Creek watershed is flat to slightly rolling. The exceptions are low hills associated with the Lake Iroquois Shoreline, notably the Kinsale Raised Shoreline immediately west of Audley Road and south of Highway 7, and the main valley feature of Carruthers Creek which forms a distinct but shallow ravine from Taunton Road south to Highway 401. Carruthers Creek s headwaters form to the south of the Oak Ridges Moraine in the City of Pickering. Both the east and west branches of the creek originate north of Concession 8; the confluence is immediately north of Taunton Road and the creek enters Lake Ontario in the Town of Ajax. Carruthers Creek contains a total of 61 kilometres of stream channels. Historically, portions of the watershed would have supported cold water fish populations including Brook trout, Atlantic salmon, Slimy sculpin, and Mottled sculpin. Instream barriers to fish movement in the watershed adversely impact the aquatic system by limiting access to feeding and spawning areas, increasing water temperature, and affecting sediment transport. In addition, some instream structures increase water velocities to the point where fish passage is prevented. Instream structures that act as barriers to fish passage include dams, weirs, road and rail crossings, and some culverts. Carruthers Creek watershed lies in the Great Lakes-St. Lawrence floristic region, which is comprised of mixed coniferous-deciduous forest. There are two provincial Areas of Natural and Scientific Interest (ANSl), as designated by the Ontario Ministry of Natural Resources and Forestry, in the watershed: the Kinsale Raised Shoreline Earth Science ANSI, designated for its distinct geological character as a well preserved part of the ancient Lake Iroquois Shoreline; and Shoal Point Marsh Life Science ANSI, which is included in the coastal Carruthers Creek Wetland Complex Provincially Significant Wetland. Two smaller wetlands are evaluated as Locally Significant: the Rossland Road Wetland Complex and the Salem Road Wetland Complex. The Carruthers Creek Wetland Complex is divided into two Environmentally Significant Areas: the coastal Carruthers Marsh and the Carruthers Creek Forest, a few hundred metres inland. 1

7 Long-term precipitation and air temperature patterns in the watershed are summarised from data collected by Environment and Climate Change Canada at the nearby Oshawa Water Pollution Control Plant station. In 2015, precipitation volumes of 985 mm exceeded the 30 year ( ) normal of 892 mm, however the 2016 volumes were significantly lower at approximately 614 mm. For three of the last nine years, the total volume of precipitation exceeded the 30 year normal. Lower than normal precipitation volumes were reported in the years 2013, 2015, and Stream flow records for the watershed are related to climate patterns. Preliminary water quantity data suggest that 2015 was a wet year in terms of stream flow and 2016 was significantly drier. Although stream flow has only been measured in the watershed for a relatively short period of record, a wide range of climatic conditions has been observed. Carruthers Creek watershed is mainly rural north of Highway 7. From Highway 7 south to Taunton Road, the majority of lands are in the Protected Countryside of the provincial Greenbelt, however there is a noticeable loss of the integrity of the natural heritage system due to clearing of vegetation and filling. Low to medium density suburban development predominates from Taunton Road south to the lakeshore. Lands currently mapped as rural in the urban areas of Ajax are expected to be developed as employment lands to meet future demands. The older parts of the built urban area have little to no stormwater controls, while the newer parts include standard stormwater quality and quantity ponds accompanied by low impact development (LID) technologies. There is also a flood vulnerable area in the Pickering Beach neighbourhood of Ajax. As expected, there are differences in agricultural land use in the upper reaches versus mid-reaches of the watershed which may be attributed to land tenure, drainage and soil properties, or a combination of factors. Horticulture dominates the east branch, whereas the west branch is predominantly cash crops and at least one livestock operation, although horticulture is also present. In the urban areas of Ajax, some lands slated for development are still cultivated with cash crops as an interim use. Overall, the land use in this small watershed is in transition, therefore the characterization provided by the field work in Phase 1 of the watershed plan is an excellent benchmark for future study and decision-making. Regular monitoring during and following this watershed planning process continuously improves our understanding and will help to guide ongoing decision-making to protect, restore, and enhance Carruthers Creek watershed. 2

8 Figure 1: Carruthers Creek Watershed Plan Study Area as of

9 1.2 Why Study Headwater Drainage Features? Headwater drainage features (HDF) are small zero-order and first-order intermittent and ephemeral streams, swales, and connected headwater wetlands (CVC & TRCA 2014). HDF can have many hydrological and ecological functions which help to maintain watershed health, such as flow attenuation; water quality improvement; provision of in situ habitat for fish, insects, and amphibians; sediment regulation; and they also transport organic material as sources of food to downstream fish communities. These features may qualify as watercourses under the Conservation Authorities Act (CA Act), if they meet the definition of an identifiable depression in the ground in which flow of water regularly or continuously occurs. Land use activities associated with urbanisation and agriculture, such as tile drainage, piping, and channelization, may result in impacts to HDF that reduce their ability to perform their natural functions. This can have detrimental effects on the watershed, particularly when many HDF in the watershed are altered, because of the cumulative effects that may occur. Individually, their importance is often overlooked due to their small size and because they do not flow throughout the year, particularly during summer when monitoring of streams typically occurs. Because of this, they are often not part of typical watershed monitoring programs. For more information about the functions of HDF, impacts from land use alterations, and other useful information, please visit In 2014, TRCA and Credit Valley Conservation (CVC) adopted the Evaluation, Classification, and Management of Headwater Drainage Features Guidelines (HDF Guidelines). This document outlines a process for monitoring and assessing the natural functions of HDF in a given area so that appropriate management recommendations can be applied to protect headwater functions when alterations to these features are contemplated. The Carruthers Creek Watershed Plan is unique in that it is one of the first watershed plans to extensively apply the HDF Guidelines for the purposes of understanding HDF functions to inform the development of a watershed plan. Most of the HDF features in Carruthers Creek watershed that can be characterized through the watershed planning process are located in the whitebelt lands; this area is also the only remaining land in the watershed where the potential for land use change has not yet been contemplated. For these reasons, headwater assessments were focused in this area (Figure 2). The HDF present in Carruthers Creek watershed north of Highway 7 are characterized in this report. This information will be used to help inform decisions related to HDF management to protect, enhance, or restore their functions in later phases of the watershed plan development. If the features qualify as watercourses, then permits from TRCA under the CA Act would be required prior to any interference with these features as part of a development proposal. 4

10 Figure 2: Carruthers Creek watershed plan study area and headwater drainage features characterization area 5

11 2. Methods The evaluation methods outlined in the HDF Guidelines rely largely on data collection approaches described in the Assessing Headwater Drainage Feature module of the Ontario Stream Assessment Protocol (S4. M10.). These HDF Guidelines recommend that the following attributes of headwater drainage features be assessed: flow condition riparian vegetation fish and fish habitat terrestrial assessment Flow condition and riparian vegetation are considered to be mandatory minimum data requirements for the rapid survey type, and were the only components listed above that were completed. The HDF Guidelines only require fish and terrestrial assessments to be completed when alterations to HDF are proposed, or if there is likelihood of sensitive species and/or higher likelihood of sustained flow (i.e., intermittent or perennial) Upon a desktop review of potential sampling sites, it was likely that a high proportion of sites, other than the main branches, might be altered by tile drainage, limiting the potential for fish and amphibian habitat. In addition, the rapid survey type was employed due to time and resource limitations to applying more rigorous methods (i.e., either standard or diagnostic survey types). The intent of the Headwater Drainage Feature (HDF) assessment is to provide a general characterization of the headwater features within the watershed as part of the first phase of the watershed plan development. No alterations to these features are being proposed as part of the watershed plan development process and habitat potential was deemed to be likely relatively low, so applying the full extent of the HDF Guidelines was not required to characterize the features as per the direction provided in the guideline. As such, diagnostic methods were not deemed to be necessary and the fish and terrestrial components of the HDF Guidelines were not completed. In the event that alterations to the features are proposed following the completion of the watershed plan, then more detailed and diagnostic surveys of the features will be required by the proponent of those alterations in order to develop prescriptive management recommendations for individual reaches. For the riparian vegetation assessment, photographs taken from the field in combination with a desktop analysis of ecological land classification (ELC) data were used to determine riparian functions associated with sampled HDF. While detailed fish and terrestrial assessments were not systematically completed for all HDF sampled, incidental fish presence was recorded based on visual confirmation during each site visit and data supporting the Aquatic Habitat and Community Characterization report, developed for this watershed plan, were used. Similarly, amphibian surveys conducted in 2015 in support of the Terrestrial Biological Inventory and Assessment component of this watershed plan were used to help characterize amphibian habitat associated with HDF. Further, TRCA collects fauna data as part of its Regional Watershed Monitoring Program, so this information is 6

12 also available for the Carruthers watershed. Where possible, the presence of amphibians was verified from previous monitoring data or from the 2015 surveys. Site photos taken during each site visit are available from TRCA. 2.1 Study Design TRCA used geographic information systems (GIS), including ArcHydro, to delineate possible headwater drainage features based on TRCA s digital elevation model (DEM). ArcHydro is a set of data models and tools which can be used to define and analyse hydro-geometric networks, and depict areas on the landscape where water is likely to flow. Drainage lines were created using ArcHydro tools by setting the upper limit of the river network threshold at 2.5 hectares (0.025 km 2 ). Archydro uses the DEM to generate flow direction and flow accumulation. Each cell in the DEM (10 m x 10 m grid) is evaluated to determine if the total input flow is greater than the set threshold. Thus, each drainage line generated through this process has 2.5 hectares (250 cells) or more flowing into its upstream cell. The smaller the threshold, the denser the resulting stream network will be. By setting the stream threshold at a small value, TRCA can identify the highest number of areas on the landscape where HDF may occur, and ensure that these features are assessed as part of the field program. The drainage lines resulting from this analysis are depicted in Figure 3. Also shown on this figure is the watercourse data layer, which is an older dataset which was delineated using desktop analysis of orthophotography to determine the extent of the stream network. These watercourse features may or may not have been assessed in the field to confirm that they meet the definition of watercourse under the CA Act, however it is likely that they do qualify as watercourses. 7

13 Figure 3: Study area and ArcHydro drainage line analysis results for Carruthers Creek watershed 8

14 Using the results from the ArcHydro analysis, each drainage line was ground-truthed to confirm the presence or absence of HDF during the first site visit. A point-based approach, as described in OSAP S4.M10, was used to identify HDF and then characterize the features in a 40 metre segment, 20 m upstream and downstream of the sample point. In instances where landowner permission was not granted, data were collected from sample points located at an access point such as a road, or a private driveway where access was granted. Sample sites are shown in Figure 4 below. 2.2 Headwater Drainage Features Characterization Methodology Since HDF can vary significantly on a seasonal basis, multiple observations are needed to correctly assess their hydrology and riparian conditions. Headwater drainage features were evaluated through a series of three site visits in the spring of 2015 which were timed to coincide with the spring freshet, late spring, and late summer (Table 1) according to recommendations in the HDF Guidelines, as follows: Table 1: Headwater drainage feature site assessment dates. Both the assessment period recommended in the HDF Guidelines and the actual field site visit dates are indicated. Site Visit Guideline Assessment Period Field Visit Dates 1 Spring freshet (Early April to mid-april) April 1 - April 28, Late April to May May 25 - May 29, July to August August 25 - August The findings of the HDF evaluation were then translated into a classification of the HDF with respect to the hydrology and the riparian vegetation conditions of the features. A summary of how these classifications were assigned is provided below. 9

15 Figure 4: Headwater drainage feature sampling locations. Due to the scale of the map, proximal site visit locations may appear to occur in slightly different locations or indicate different findings, however these occurrences actually represent different features. 10

16 2.2.1 Hydrology Classification Methodology Each sampled HDF was categorised as one of the following feature types, which describe the feature s form and associated functions, determined based on definitions provided in the HDF Guidelines: defined natural channel (visible banks) channelized (historically natural channel, now straight with banks) multi-thread (> 1 channel) no defined feature (overland flow only) tiled drainage (buried stream/pipe with outlet) wetland swale roadside ditch (channelized running parallel with roadway), or online pond outlet Each sampled HDF was also categorised according to its flow conditions, described as one of the following: no surface water (dry) standing water interstitial flow surface flow minimal (<0.5 l/s), or surface flow substantial (>0.5 l/s) When flow was greater than 0.5 l/s, it was measured in one of two ways during each of the three site visits: 1) distance by time, which includes measuring the amount of time it takes a floating object to travel a known distance; or 2) volume by time, which includes measuring the amount of time it takes to fill a container of known volume. The first site visit was used to establish the feature type and flow condition. If a drainage feature was dry on the first site visit it was not visited again. If a drainage feature was not dry on the first site visit but was dry on the second site visit it was not visited a third time. If a drainage feature was not dry on the first two site visits, a third site visit was undertaken to confirm the presence of perennial flow. Using both the feature type (form) and the flow condition, the HDF was then assigned a hydrology classification which includes one of the following: important, valued, contributing, recharge, or limited. These are briefly described below (see CVC and TRCA 2014 for further detail): Important Functions Perennial: Water is present throughout the year, as either flowing or standing surface water (wetlands or refuge pools) as a result of year round groundwater discharge (i.e., seeps, springs, wetlands, upwelling). 11

17 Valued Functions Intermittent: Water is present in the spring as a result of seasonally high groundwater discharge or seasonally extended contributions from wetlands or other areas that support intermittent flow or water storage conditions. These features are typically still flowing in late spring but dry or surface-damp by July. Contributing Functions Ephemeral: Provides ephemeral flow or water storage functions during and (for a short time) after spring freshet and following large rain events only. These features are typically dry or surfacedamp by mid-may. Recharge/Limited Functions Dry or Standing Water: No surface flow occurs, however the key function may include groundwater recharge Riparian Classification Methodology The categorisation of riparian vegetation was based on desktop analysis of site photos. The vegetation category assigned through analysis of the site photos was confirmed by a GIS analysis of available ecological land classification (ELC) data or TRCA s natural habitat features layer (Figure 5 and Figure 6). Riparian vegetation was categorised into seven different types: forest, scrubland, wetland, meadow, lawn, cropped, or none (OSAP S4. M10). Riparian habitat was classified into four categories based on function associated with the vegetation types according to the HDF Guidelines. These categories are defined as follows: Important Functions the feature type is wetland and/or any of the riparian corridor categories (0-1.5 m, m, or m on either side of the feature), dominated by forest or thicket/scrubland communities or wetland. Valued Functions any of the riparian corridor categories (0-1.5 m, m, or m on either side of the feature) is dominated by meadow and there are no important riparian functions. Contributing Functions the riparian corridor (0-1.5 m, m, or m on either side of the feature) is dominated by lawn and there are no important or valued riparian functions. Limited Functions the riparian corridor (0-1.5 m, m, or m on either side of the feature) is dominated by cropped land or no vegetation, and there are no important, valued or contributing riparian functions. 12

18 Figure 5: Ecological Land Classification (ELC) mapping for study area 13

19 Figure 6: TRCA s natural cover layer for study area 14

20 2.2.3 Fish and Terrestrial Data Collection Methodology For information about the fish and terrestrial data collection methodologies employed to support the Carruthers Creek Watershed Plan development, please see the Aquatic Habitat and Community Characterization and the Terrestrial Biological Inventory and Assessment reports. 15

21 3. Classification Results A total of 443 individual sites were sampled during the three site visits to characterize the headwater drainage features of Carruthers Creek watershed. This included 280 locations surveyed during the first site visit and an additional 163 locations surveyed on both the second and third visits. An additional 28 possible HDF could not be characterized due to lack of access. The results of the hydrology and riparian classifications are provided below. Data collected and the results used to generate the following tables and figures are available from TRCA upon request. 3.1 Hydrology Classification Results The most common feature type encountered was tile drains (41%), followed by defined natural channels (22%) and roadside ditches (21%) (Figure 7). Locations and distribution of the various feature types in the study area are presented in Figure 8. The location of features classified as tile drains are indicated where the tile drain outlets to the creek. The results suggest that only 33% of the HDF sampled qualify as natural or unaltered types of features, including defined natural channels, wetlands, swales, and multi-thread channels. The remaining features, 67%, have been altered in some way by human activities. 16

22 2.02% 21.39% 22.54% Defined Natural Channel Channelized Multi-thread 3.47% 4.05% 2.31% 2.60% 0.58% No defined feature Tile Drain Wetland Swale Roadside Ditch Pond Outlet 41.04% Figure 7: Proportion of HDF by feature type 17

23 Figure 8: Location of HDF by feature type. Due to the scale of the map, it may appear that the main Carruthers Creek is tile drained, however this actually represents where the tile draining the adjacent agricultural land outlets to the main creek. 18

24 During the first site visit, a total of 134 HDF were dry, and 17 had no flow but contained standing water. During the second site visit, 32 HDF were found to be dry, and 8 had standing water with no flow. Based on the results from the three visits, a total of 48% of the HDF were classified as having a limited/recharge function as they were dry or only had standing water during the first two site visits (total of 164 locations). The proportion of HDF classified as having a valued/contributing hydrology function was 31%, with the remaining 22% classified as having an important function, which meant that the feature had water present during the third site visit (Figure 9). The third site visit yielded 38 dry features, and as such, their hydrological function was assessed based on data collected during the first and second site visits. The location and distribution of HDF based on their hydrology classification is presented in Figure 10. Data was extrapolated from the point and applied reach(es) according to the direction provided in the guideline. 22% 48% Important Hydrology Functions Valued or Contributing Hydrology Functions 31% Limited or Recharge Hydrology Functions Figure 9: Proportion of HDF by their assigned hydrology classification 19

25 Figure 10: Location of HDF and their hydrological classification. Point data represent the flow observations at that location. Line data represent the extrapolated hydrological classification for the reach according to directions provided in the guideline. 20

26 Standing or flowing water was present throughout the year at 19% of roadside ditches and 7% of tile drains, indicating that these features have an important hydrological function. Another 15% of tile drains and 30% of roadside ditches had a valued/contributing hydrological function as they had water present in the spring during the freshet, and during the late spring or early summer season (Table 2). Table 2: Proportion of feature types classified by hydrology function Defined Natural Channel Channelized Multi thread No defined feature Tile Drain Wetland Swale Roadside Ditch Pond Outlet Important 50% 25% 33% 0% 7% 43% 0% 19% 0% Valued or Contributing 50% 63% 67% 0% 15% 43% 9% 30% 71% Limited or Recharge 0% 12% 0% 100% 78% 14% 91% 51% 29% As noted above, 62% of the HDF sampled are either tile drains or roadside ditches. Tile drains and roadside ditches are typically considered to have altered hydrology since they are either buried or flow through human made channels. However, approximately 20% of the tile drains and 50% of the roadside ditches sampled are assigned as either important or valued/contributing hydrological classifications. Despite their altered state, these features appear to convey flow to the main branch of Carruthers Creek for sustained periods of time, either intermittently or perennially. As such, these features may be sources of habitat and/or refuge, or contribute to habitat important for fish, amphibians, or benthic macro invertebrates (BMI) given that there are no barriers preventing these organisms from accessing these features. 3.2 Riparian Classification Results The most common vegetation type encountered in the riparian zones of the sampled HDF was meadow (38%), followed by agricultural crop land (22%). Other vegetation types observed at sampled HDF included wetland vegetation at 14% of sites, forest vegetation at 17%, and scrubland vegetation at 6%. Vegetation types Lawn or none were each observed at only 2% of the HDF sampling sites (Table 3). Based on riparian vegetation type, 37% of HDF were classified as having important riparian functions, 38% had valued riparian functions, 2% had contributing functions, and 24% had limited functions (Figure 11). 21

27 Table 3: Proportion of HDF by their assigned riparian classification and vegetation type Riparian Classification Classification Important 37% Valued 38% Contributing 2% Limited 24% Vegetation Type Wetland Forest Scrubland Meadow Lawn Cropped None % 14% 17% 6% 38% 2% 22% 2% 24% 37% Important Riparian Functions 2% Valued Riparian Functions Contributing Riparian Functions Limited Riparian Functions 38% Figure 11: Proportion of HDF by their assigned riparian classification. TRCA compared riparian vegetation observed for HDF according to feature type, the results are summarised in Figure 12 and Table 1. Defined natural channels, multi-thread, wetland, and pond outlet feature types had the highest proportion of their riparian vegetation characterized by wetland, forest, or scrubland communities, which are all considered to have important riparian functions. Tile drains and swales tended to have the highest proportion of their riparian zone dominated by no or cropped vegetation, suggesting that these features had limited riparian functions. However, 20% of tile drains had a riparian community characteristic of a wetland, forest, or scrubland, and another 27% were associated with meadows. These tile drains were classified as having riparian habitat with important or valued riparian functions, respectively. 22

28 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Wetland Forest Scrubland Meadow Lawn Cropped None HDF Feature Type Figure 12: Proportion of HDF feature types by riparian vegetation type The majority (69%) of roadside ditches had valued riparian functions associated with meadow riparian vegetation, and an additional 26% of roadside ditches had important riparian functions associated with wetland, forest, or scrubland riparian vegetationerror! Reference source not found.. A high proportion (62%) of channelized HDF had valued riparian functions associated with meadow vegetation, and 38% of these feature types had limited functions associated with either no or cropped vegetation. HDF that had no defined feature as the feature type were considered to have important or valued riparian vegetation at 50% of the sampled HDF sites each. Figure 13 depicts the location of HDF and their assigned riparian classification based on the above noted results. Table 4: Proportion of HDF feature types by riparian classification Defined Natural Channel Channelized Multi thread No defined feature Tile Drain Wetland Swale Roadside Ditch Pond Outlet Important 55% 0% 100% 50% 20% 79% 0% 26% 86% Valued 44% 62% 0% 50% 27% 21% 17% 69% 14% Contributing 1% 0% 0% 0% 2% 0% 0% 4% 0% Limited 0% 38% 0% 0% 51% 0% 83% 1% 0% 23

29 Figure 13: Location of HDF and their assigned riparian classification 24

30 3.3 Fish and Terrestrial Habitat Data Results Recall that the rapid survey type method employed during this study does not require the collection of fish and amphibian habitat data. However, data from fish and amphibian sampling efforts in support of the Aquatic Habitat and Community Characterization and the Terrestrial Biological Inventory and Assessment components of the Carruthers Creek Watershed Plan and TRCA s Regional Watershed Monitoring Program were used to assist in characterizing the fish and amphibian habitat associated with the HDF in the watershed, respectively. Data on available fish and amphibian habitat are noted below, however we do not provide fish or terrestrial habitat classifications as outlined in the HDF Guidelines. Fish were found at five locations, all in the perennial segments of Carruthers Creek (Figure 14). Amphibian species were recorded at 55 locations at or near HDF, and included green frog (Rana clamitans), wood frog (Lithobates sylvaticus), spring peeper (Pseudacris crucifer), and grey tree frog (Hyla versicolor). Table 5 references the location where amphibians and fish were found within or in close proximity to the HDF sampling point. Amphibian species were recorded, however fish observations were incidental and species were not determined. Additional data on fish communities is available in the Carruthers Creek Watershed Aquatic Habitat and Community Characterization Report. 25

31 Table 5: Amphibian species and fish records found in proximity to HDF sampling locations Map Point Amphibian Species Fish Record Map Point Amphibian Species Fish Record Map Point Amphibian Species Fish Record wood frog, grey tree frog, green frog, spring peeper wood frog, grey tree frog, green frog, spring peeper wood frog, grey tree frog, green frog, spring peeper wood frog wood frog 188 green frog, wood frog spring peeper, wood frog spring peeper, wood frog wood frog, spring peeper wood frog, spring peeper 281 spring peeper 282 spring peeper 283 spring peeper wood frog, grey tree frog, green frog, spring peeper wood frog, grey tree frog, green frog, spring peeper 52 wood frog 200 grey tree frog 336 Present 53 wood frog 203 spring peeper, wood frog 337 Present 69 spring peeper, wood frog 207 spring peeper, wood frog 406 spring peeper, wood frog 70 spring peeper, wood frog 208 spring peeper, wood frog 511 American Toad 71 spring peeper, wood frog 216 green frog, wood frog 530 Present 72 spring peeper, wood frog 217 green frog, wood frog 547 Present 73 spring peeper, wood frog 218 green frog, wood frog 552 Present 77 spring peeper, wood frog 219 green frog, wood frog 556 spring peeper 78 spring peeper, wood frog 226 green frog 79 wood frog 227 green frog 80 wood frog 228 green frog 81 American toad 229 green frog 82 spring peeper, wood frog 230 green frog 86 green frog 231 green frog 87 green frog 232 green frog 88 green frog green frog green frog 235 grey tree frog, green frog grey tree frog, green frog grey tree frog, green frog 91 green frog, wood frog 245 Present 26

32 Figure 14: HDF sampling locations where fish and/or amphibians were observed. Refer to Table 5 for species observations at each sampling location. 27

33 4. Conclusions In this report, TRCA provides a characterization of the hydrological and riparian functions of HDF north of Highway 7 in Carruthers Creek watershed. The most common types of HDF observed were tile drains, roadside ditches, and defined natural channels. The results suggest that one third of the HDF sampled qualify as natural or unaltered types of features, including defined natural channels, wetlands, swales, and multi-thread channels. The remaining two-thirds of the features have been altered in some way by human activities, with varied levels of impact on natural headwater functions. While the installation of tile drains is an accepted practice to maximise agricultural yields and facilitate the initiation of farming practices earlier in the season, there are potential effects on the local natural hydrology. By burying flow underground in pipes, tile drains efficiently move water off agricultural lands, often eliminating the wetlands and riparian vegetation that develop when water remains for extended periods on the surface of soils. Wetland and riparian vegetation act to slow down and attenuate flow, reduce erosion, help to improve water quality, and provide habitat to many species of organisms. In eliminating these features, tile drainage is an activity that likely has one of the greatest impacts on headwater functions in agricultural landscapes. The fact that so many headwater drainage features have been altered in the watershed suggests that headwater functions have already been impaired. While tile drains appear to have a major influence on the ecological and hydrological functioning of headwater drainage features within the watershed, it is recognized that tile drainage is a long established and accepted agricultural practice that is important to the economic sustainability of the agricultural industry. Local food production has many environmental benefits that need to be considered, and the farming community are important environmental stewards of their land. Much research is being undertaken on this topic, and TRCA will continue to work with the farming community to better understand and develop the innovative practices needed to ensure that the health and sustainability of the watershed is protected, enhanced, and restored now and in the future. 28

34 5. References Credit Valley Conservation and Toronto and Region Conservation, Evaluation, Classification and Management of Headwater Drainage Feature Guidelines. Credit Valley Conservation Authority and Toronto and Region Conservation Authority. Available online: Ontario Ministry of Municipal Affairs and Housing, Greenbelt Plan. Ontario Ministry of Municipal Affairs and Housing. Available online: Ontario Ministry of Natural Resources, Ontario Stream Assessment Protocol Version 9.0. Stanfield, L. Ontario Ministry of Natural Resources, Fisheries Policy Section. Peterborough, Ontario. Toronto and Region Conservation Authority, A Watershed Plan for Duffins Creek and Carruthers Creek. Toronto and Region Conservation Authority. Available online: Toronto and Region Conservation Authority, The Natural Functions of Headwater Drainage Features: A Literature Review. Toronto and Region Conservation Authority. Available online: 29