Duffins Creek State of the Watershed Report Surface Water Quality June 2002

Other topics in this series for both the Duffins Creek and the Carrthers Creek include:

Introduction Study Area Human Heritage Greenspace, Trails and Recreation Land Use Air Quality Climate Surface Water Quantity Stormwater Management Fluvial Geomorphology Hydrogeology Aquatic Habitat and Species Terrestrial Natural Heritage

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Toronto and Region Conservation, 5 Shoreham Drive, Downsview, Ontario M3N 1S4 Telephone: (416) 661-6600 Fax: (416) 661-6898 www.trca.on.ca Table of Contents

Introduction to Surface Water Quality ...... 2

Current Conditions ...... 5 Implications for Swimming and Body Contact Recreation ...... 5 Implications for Aquatic Health ...... 7 Implications for Human Health ...... 10

Factors Affecting Water Quality Conditions ...... 12 Natural 12 Land Use Activities ...... 14 Sanitary Servicing ...... 14 Stormwater Runoff ...... 14 Rural/Agricultural Activities ...... 16 Spills and Illicit Discharges ...... 17 Golf Courses ...... 17 Landfills ...... 18 A Future Airport ...... 18 Pet and Wildlife Faeces ...... 18 Atmospheric Deposition ...... 19

Summary ...... 20

References ...... 21

Tables and Figures Table 1: Rationale for the Selection of Key Water Quality Parameters ...... 3

Figure 1: Chloride Levels in Toronto Area Streams ...... 4 Figure 2: Suspended Sediment Concentration in Toronto Area Streams ...... 5 Figure 3: Historic Dissolved Oxygen Levels, 1960-1970 ...... 6 Figure 4: Duffins Creek (Bayly Street) Phosphorus Levels ...... 8 Figure 5: Duffins Creek (Bayly Street) Dissolved Oxygen and Biological Demand ...... 9 Figure 6: Duffins Creek (Bayly Street) Chlorides ...... 10 Figure 7: Duffins Creek (Bayly Street) Total Suspended Sediment ...... 11 Figure 8: Relative per cent distribution of baseflow by subwatershed, Duffins Creek ...... 13 Figure 9: Duffins Creek Chloride Levels and Land Use ...... 15 Figure 10: Average Daily Traffic ...... 16 Figure 11: Median Annual Chloride Concentration Over Time Bayly Street ...... 17

1 Introduction to Surface Water Quality

Water quality in Duffins Creek is understood by addressing the following questions:

What are the current water quality conditions? Do they vary throughout the watershed? Is water quality getting better or worse? Is the water suitable for various uses? Does it meet federal of provincial objectives?

What are the factors that influence water quality?

Water quality data from Ontarios Provincial Water Quality Monitoring Network (PWQMN) provide a basis for this assessment. Data are available for six monitoring stations for a period of about 20 years. Data from the period of 1988 to 1993 were considered to represent current conditions, as 1993 was the last year of monitoring under the PWQMN. This information was augmented with baseflow chemistry data collected at 110 stations during 1995 and 1996 by the Geological Survey of Canada. Water Survey of Canada stream flow and suspended solids data were also evaluated for up to 10 monitoring stations, operated during 1975 to 1978 in the watershed.

The assessment focused on selected water quality parameters: phosphorus, nitrogen compounds, suspended solids, chlorides, bacteria (E. coli and faecal coliform), biological oxygen demand, dissolved oxygen, and temperature. These parameters were selected for analysis due to their relevance to common water use concerns (Table 1). While heavy metals and persistent organic pollutants (e.g., pesticides) are also of interest, an accurate assessment of these parameters is not possible with the data provided by the above- noted monitoring sources. The presence of these pollutants is addressed with reference to other indicators and observations in nearby watersheds. Table 1 also includes provincial and federal water quality objectives or guidelines where they exist, however, some parameters are without guidelines as there is a process currently underway to standardize these across the country. 2 Table 1: Rationale for the Selection of Key Water Quality Parameters

Water Quality Parameter Significance and Sources Phosphorus Phosphorus is a nutrient that influences eutrophication by fuelling plant and algae growth, reducing water clarity and oxygen availability. Sources of phosphorus include: lawn and garden fertilizers, eroded soil particles from construction sites, stream banks, agricultural fields and sanitary sewage. A firm Provincial Water Quality Objective (PWQO) for the protection of aquatic life does not exist at this time, however a general provincial guideline of no more than 0.03 mg/L is recommended in the interim. Nitrogen Compounds Nitrogen, in the form of nitrate, is a nutrient with sources and effects similar to phosphorus. It is also potentially toxic in aquatic systems when in the form of ammonia or nitrite, the later of which is a very transient stage in the nitrification process converting ammonia to nitrate. A firm PWQO does not exist for nitrate at this time, however sustained high levels (e.g., 1-10 mg/L) are suspected to stress aquatic life. The PWQO for unionized ammonia (a toxic form of nitrogen) is 0.02 mg/L. Suspended Sediment The presence of suspended sediment in water influences water clarity and aesthetics. Water quality can also be affected because other contaminants tend to adhere to sediment particles. Suspended sediment also can impair fish habitat and spawning areas, as well as abrade fish gills. Sources include: areas of soil disturbance (such as construction sites or farm fields), eroding streambanks and streambeds and grit accumulated on urban streets. Concentrations not exceeding natural background levels +25 mg/L are recommended for the protection of aquatic life (CWQG, 1999). Chloride The chloride ion is a widely distributed in the environment. It is released through the natural process of weathering and is also linked to many human activities such as road salting, industrial wastes and domestic sewage discharge. It is potentially toxic at elevated levels and a study by Environment Canada has assessed the impact of chlorides on aquatic life. Its presence at elevated levels correlates well with degradation of the chemical, physical and biological features of urban streams. At this time, there is no numerical standard for chloride concentrations Bacteria High faecal bacteria levels in a water body are indicative of loadings of faecal matter of either animal or human origin. Stormwater runoff carries bacteria from pet and wildlife faeces and bacteria in association with suspended sediment particles to the watercourse. The Provincial Water Quality Objective for Recreation limits bacteria Escherichia coli levels to a maximum of 100 counts per 100 mL. Formerly, faecal coliform and total coliform were measured as indicators of health risk with respective limits of 100 and 1000 counts per 100 mL. Table 1 continues on page 4.

3 Table 1: Continues from page 3

Water Quality Parameter Significance and Sources Biological Oxygen The BOD of water corresponds to the amount of oxygen required for Demand (BOD) and aerobic microorganisms to oxidize organic matter to a stable inorganic Dissolved Oxygen form. High BOD levels correspond to low dissolved oxygen concentrations, which can lead to stress responses in aquatic organisms. No official guideline for BOD exists. BOD levels above 2 mg/L (or 5 mg/L during exclusively dry weather) indicate the presence of a persistent organic load to the system. The Canadian water quality objective for dissolved oxygen ranges from 5.0- 6.0 mg/l for warm water biota and 6.5-9.5 mg/l for cold water biota, depending on life stages. Summer Water Extreme water temperatures can impact fisheries and benthic communities, Temperature promote eutrophication and influence the presence of other water quality parameters (i.e. dissolved oxygen, ammonia). Water temperature is influence by groundwater inputs, streamside riparian cover and land use.

The following sections summarize the results of this water quality assessment. Detailed data summaries are included within the Duffins Water Quality Technical Appendix (TRCA, 2000).

Figure 1 Chloride Levels in Toronto Area Streams 4 Figure 2 Suspended Sediment Concentration in Toronto Area Streams

more impacted by septic systems, wastewater Current treatment plants, and other BOD discharges. Conditions Water quality in Duffins Creek can best be described in terms of its implications for The Duffins Creek tributaries have good water swimming, aquatic health and human health. For quality conditions overall. In fact, Duffins Creek each concern: key parameters are identified; the exhibits among the best water quality conditions pattern of pollutant levels throughout the of all other streams in the Toronto region, as watershed is described; a comparison to objectives shown in Figures 1 and 2. These maps show is provided; and trends over time are noted. mean concentrations of suspended sediment and chlorides in Duffins Creek, relative to other local Implications for Swimming streams. Good water quality conditions have and Body Contact Recreation been prevalent for some time in Duffins Creek. Figure 3 illustrates that, even in the 1960s, mean The shallow depths, soft bottom and naturally dissolved oxygen concentrations in Duffins cool temperatures of the Duffins Creek do not Creek were at relatively desirable levels as make the watercourse particularly suited to compared to other Toronto streams, which were swimming or wading. Its recreational amenities 5 Figure 3 Historic Dissolved Oxygen Levels, 1960-1970

offer other opportunities for water-body contact conditions. Levels increase toward the lower and therefore pose human health concerns. The reaches of the watershed, failing to meet water Town of Ajax cautions citizens about creek water recreation objectives 65-75 per cent of the time. and has never encouraged swimming in the These provincial measurements are likely an Creek (Town of Ajax, 2000). Swimming in the underestimate of bacteria levels in the creek Duffins watershed is only encouraged at public because sampling for the network is biased waterfront beaches. towards dry weather, a time characterized by low bacteria levels. During and shortly after wet Escherichia coli (E. coli) or other faecal coliform weather, it is not unusual for bacteria levels to be bacteria indicate the presence of faecal matter of several orders of magnitude higher even in human or animal origin and can indicate the pristine watercourses. While other streams in the potential presence of other bacteria, viruses or Toronto region have experienced a consistently pathogens that could infect humans, pets and increasing trend in bacteria levels over the past other warm-blooded animals. High bacteria 20 years, certain tributaries in the Duffins Creek levels necessitate the closure of swimming system have either remained at stable levels or beaches and create health risks associated with have decreased. other forms of body contact recreation. Bacteria levels monitored through the provincial water Bacteria loadings from Duffins Creek, like all quality monitoring network in the upper watercourses draining to Lake Ontario, watershed areas (e.g., Stouffville Creek, Reesor contribute to bacteria levels in the nearshore Creek, Brougham Creek) fail to meet objectives zone of the lake. Rotary Park Beach is located on for water recreation 35-45 per cent of the time. Lake Ontario near the mouth of Duffins Creek. These levels are just slightly higher than would That beach was closed for 55 per cent of the be expected under natural, background swimming season (June to September) in 1999 6 due to excessive bacteria levels (Durham between nitrate levels and land use is a good Regional Health Department, 1999). In barometer of anthropogenic influences to the comparison to other nearby waterfront beaches overall aquatic system. at Rouge and Bluffers Park, these beaches were posted as unsafe much more frequently in the Phosphorus levels increase by up to several orders same year (> 95 per cent). of magnitude during wet weather conditions. From an overall loading perspective to the Implications for watershed, phosphorus contributions are at their Aquatic Health highest from late fall to spring. This is attributed to current tillage practices and limited crop cover Various land use activities generate pollutants in the watershed during these months in that adversely affect aquatic habitat and species. combination with spring snowmelt and rainfall. Conventional pollutants can fuel plant growth, limit oxygen availability, reduce water clarity and Although the nitrate form of nitrogen acts be potentially toxic to aquatic life. Parameters of principally as a nutrient, very high and sustained interest include phosphorus, nitrogen, biological levels of nitrate (i.e. 1 - 10 mg/L) may have an oxygen demand, suspended sediment and turbidity, indirect role in aquatic toxicity by contributing chlorides and temperature (Figures 4-7). as a stress on the aquatic system. Another form of nitrogen, ammonia, is a toxic form that is a The nutrients phosphorus and nitrate are component of human and animal sewage and elevated in the watershed. Trends and effects are also forms from the microbial decomposition of similar for both these nutrients. Median organic tissue. Ammonia levels meet Provincial phosphorus concentrations (defined as the Water Quality Objectives (PWQO) virtually all middle value in an ordered data set) meet the of the time, with only one exceedence in the data interim provincial phosphorus guideline of 0.03 collected during the period 1988 to 1994 at mg/L throughout the watershed, except in Urfe monitoring sites on the West Duffins, Reesor Creek, lower Stouffville Creek and the west Creek and Brougham Creek tributaries. Duffins. These tributaries are impacted by local agricultural and/or urban runoff and effluent The decommissioning of the Stouffville Sewage from the Stouffville sewage treatment plant Treatment Plant on Stouffville Creek is currently (STP). Sources of phosphorus and nitrate include underway and improvements in water quality lawn, garden and agricultural fertilizers and are expected. In the urban areas, however, eroded soil particles from construction sites, nutrient levels are expected to rise once again as stream banks and agricultural fields. Phosphorus stormwater runoff increases. In rural areas, the readily binds to soil particles and ends up in the retention of vegetation cover during the winter creek when soil particles are washed off during would improve water quality. storm events. Phosphorus concentrations dropped significantly around 1980 due to improvements Another water quality parameter closely following of the Sewage Treatment Plant (Figure 4) and the phosphorus trend is biological oxygen changes in farming practices in the watershed. demand. Biological oxygen demand (BOD) is Isolated periods of increased levels of phosphorus elevated in Stouffville Creek, lower West in the mid to late 1980s originated from disturbed Duffins, Ganatsekiagon and Urfe Creeks relative soils at construction sites associated with the to other Duffins tributaries. Organic loads in expanding housing market at that time. High effluent from the Stouffville sewage treatment nitrate levels in combination with increased stream plant represent the primary cause of BOD. Farm temperature and decreased stream shading can runoff or septic leachate is the primary factor exacerbate eutrophication problems associated affecting BOD in the Ganatsekiagon and Urfe with elevated nutrient levels. The relationship Creeks. Like the improvements in phosphorus 7 Figure 4 Duffins Creek (Bayly Street) Phosphorus Levels

levels in the lower Duffins Creek in the early networks is the primary source of chlorides, 1980s, a reduction in BOD was also due to however septic fields, sewage treatment plants upgrades at the sewage treatment plant which and landfill leachates are also minor sources improved effluent quality (Figure 5). Consistent (Bowen and Hinton, 1998). Chlorides are known with the decline in BOD, dissolved oxygen (DO) to be a general indicator of human disturbance levels have increased. Seasonally, BOD is and also indicate the presence of other relatively constant. pollutants. Elevated levels in the greater Toronto area watersheds (Figure 1) correlate well with Throughout the year, dissolved oxygen observations of degraded aquatic systems, such fluctuates in relation to temperature, with as systems with extensive physical alterations to warmer water capable of holding less dissolved channels (Bowen and Hinton, 1988). oxygen. During the day, aquatic plants produce oxygen and at night respiration processes take During 1988-1993, levels at Bayly Street and in up dissolved oxygen. These factors lead to drastic Stouffville Creek downstream of the sewage swings in dissolved oxygen levels between night treatment plant occasionally (2 per cent of the and daytime. Periods of rapid plant decomposition time) exceed levels of concern for aquatic life. during the summer months can further exacerbate This assessment is based on an Environment dissolved oxygen levels. In the Duffins Creek, Canada study (2000) which reported that the lowest DO levels occur in July to August, chloride levels > 230 mg/l cause chroric effects however levels remain above the minimum level on sensitive aquatic organisms. Chlorides have a for cold water fisheries. Overall, current BOD and strong seasonal trend, with the highest levels dissolved oxygen levels in the Duffins Creek are occurring during the winter months. well within the acceptable range for aquatic life. Suspended sediment levels in streams are a Chloride concentrations have been increasing function of particulate matter picked up during over the years (Figure 6). Current levels remain overland transport as well as instream erosion low in the rural portions of the watershed. Road and scouring of the stream bed. Total suspended salt associated with runoff from transportation sediment (TSS) concentrations are low in the 8 upper portions of the watershed due to drier periods. TSS levels in Reesor Creek during significant areas of forested lands, good riparian 28 rain events sampled in 1997-1998 were an vegetation and stabilized streambanks. In the order of magnitude higher (NWRI and TRCA, lower watersheds (eg. Urfe and Ganatsekiagon), 2000) than monitored through the PWQMN the streams pass through the Iroquois Shoreline (median of 65 mg/L compared to 7 mg/L), the and enter urban areas, which represent increased latter of which is biased towards monitoring sources of sediment. The highest TSS concentrations during dry weather conditions. At any time of occur in late winter and early spring when soils the year, high suspended solid levels may occur are exposed, particularly in agricultural areas. in streams during wet weather and significant High snowmelt and rainfall volumes at that runoff periods. Aquatic life are adapted to time, combined with low evaporation rates, occasional periods of elevated suspended solid further enhance runoff volumes and support the levels, however they become stressed during elevated levels. In the summer months, the prolonged, frequent periods of moderate to high delivery mechanism for TSS, stormwater runoff, concentrations of suspended sediment. is slowed by the presence of crop cover. It is also reduced in volume as soil moisture evaporation Stream temperatures in the Duffins watershed rates are high, thus suspended sediment levels support cold water fish species with an average tend to be low (median less than 10 mg/L). summer temperature of 15°C. Maximum summer temperatures over the 1988-1993 period reach Over time there has been little change in 20°C. The key factors contributing to the cool suspended sediment or turbidity levels in the water regime include the significant groundwater Duffins, except for some elevation in the 1980s inputs at many locations along the watercourse, in association with the housing boom (Figure 7). as well as shading provided by stream side Both increase during wet periods and decrease in riparian vegetation in several tributaries.

Figure 5 Duffins Creek (Bayly Street) Dissolved Oxygen and Biological Oxygen Demand 9 Figure 6 Duffins Creek (Bayly Street) Chlorides

Implications for Human Health system. Endocrine disruption could result in birth defects, depressed immune systems and Pesticides, PCBs and polynuclear aromatic behavioural changes. hydrocarbons (PAHs) are synthetic substances which are not found naturally in the environment. Toxic pollutant data from the 1991-92 Toronto Their detection in water is therefore a cause for stream study showed that wet weather contaminant some concern. Metals, although naturally concentrations generally exceed dry weather present in the environment, are released at concentrations by an order of magnitude for excessive levels as a result of various land use suspended solids, total phosphorus, E. coli, activities. Certain pesticides have been banned aluminum, iron, and most organic compounds. for use due to their persistence and tendencies to Neither Duffins or Carruthers Creeks were bioaccumulate through the food chain. included in the study, however results are expected to be similar to, if not better than, Many of these substances have been linked to conditions reported for the neighbouring Rouge chronic health effects on aquatic organisms and River watershed by DAndrea and Anderton humans. Environmental effects in aquatic life (1996) and Boyd (1999), where levels were lower include physical deformities, tumours and lesions than all other Toronto tributaries. This inference and population declines through increased is due to similarities in the two watersheds, with embryo mortality and damage to reproductive the exception of the presence of a sewage systems. Compounds such as dieldrin and treatment plant on the Stouffville Creek benzo(a)pyrene are believed to be carcinogenic to tributary of the Duffins. humans. Some researchers are concerned that exposure to toxics at the human embryo stage In 2000 2001, an innovative sampling program may affect learning capacity later in life and may was undertaken by Ministry of the Environment disrupt the function of the endocrine (hormone) (MOE) to provide reliable data for a number of 10 Figure 7 Duffins Creek (Bayly Street) Total Suspended Sediment heavy metals and trace organic contaminants in Duffins. The Guide to Eating Ontario (e.g., organochlorine pesticides, chlorobenzene, Sportfish (MOE, 1999) places only the minimum PAHs, and volatile organic compounds) in the restriction on eating brook trout from the East Duffins Creek. An assessment of the presence of and West Duffins Creek. The Guide does place pesticides, PCBs, or metals has not been made in greater restrictions on consumption of fish from the past because of limitations in water quality Duffins Creek Marsh, however contaminant sampling methodologies or simply a lack of data. levels in these fish could be influenced by Preliminary results indicate that the majority of conditions in Lake Ontario. Analysis of brown organic parameters evaluated were not detected bullhead and carp tissue for a group of in the Duffins watershed, and of the few organic contaminants (mercury, PCBs, mirex, photomirex parameters detected, all occurred in very trace and various pesticides) indicated that consumption amounts (less than a few parts per billion) of large bullhead should be limited to two-four (D. Boyd, Personal Communication, 2001). meals per month and large carp to one-two Metals concentrations were also within normal meals per month. background levels found in nature. In comparison to other Toronto area watersheds evaluated in the Young of the year forage fish biomonitoring in study (Don and Humber rivers), fewer parameters 1997 found small amounts of PCBs and DDT, were detected and overall concentration levels although levels are well below International were lower, a result that would be expected in a Joint Commission Aquatic Life Guidelines. No watershed with less intensive land use activities. other contaminants were detected in the forage A complete analysis of the results will be fish samples from the Duffins Creek. undertaken by MOE in the near future.

Based on other biological indicators there is no evidence of toxic organic contaminant problems 11 Although aquifer quality is relatively good, some Factors Affecting localized areas of elevated chloride concentrations may further aggravate chloride impacts from Water Quality surface water sources. Groundwater seeps along the Iroquois Shoreline in the mid reaches of Conditions Duffins Creek and may carry naturally elevated levels of iron leached from native soils. This may Water quality conditions in the Duffins creek influence stream iron concentrations. watershed are influenced by natural conditions and land use activities in the watershed. The biological features of the Duffins Creek watershed, particularly the significant extent of Natural forest cover, wetlands and riparian habitat, have a positive influence on surface water quality. The Natural features and functions within a presence of vegetation itself intercepts rainfall, watershed influence the quality and prevalence impedes overland flow and promotes infiltration. of water resources and determine the extent to Vegetation also uses water for growth. All of which the natural system can moderate the these factors reduce the quantity of runoff to effects of human activities. streams and therefore the capacity for overland pollutant transport. Vegetation binds and The geology and soils in parts of the Duffins stabilizes soil, thereby reducing the potential for Creek watershed are naturally conducive to good soil and streambank erosion. Water quality surface water quality. The upper West Duffins and studies in the Duffins Creek have found lower East Duffins Creek catchments have predominantly phosphorus and nitrate loads in tributaries sand and gravel based soils, which are relatively flowing from well forested catchments (Allan et pervious. These soils promote water infiltration al., 1993; Hill, 1981). Anaerobic soils and and limit stormwater runoff, a major delivery considerable water residence time in wetlands mechanism of pollutants to the watercourses. provide a natural sink for nitrate and ammonium During water quality studies in the Duffins (Hill, 1993), however the influence on Creek, Hill (1981) found lower phosphorus downstream chemistry is limited in wetlands concentrations in areas with predominantly that experience large volumes of surface runoff. sandy or sandy loam soils. In contrast, the lower Well vegetated riparian zones (i.e. stream banks) portions of the watershed are characterized by in a watershed also influence stream water fine grained soils which are highly erodable and quality by providing more effective sediment thus do not promote good water quality. traps for soils washed off during stormwater runoff events and for controlling stream bank Groundwater makes up a significant proportion erosion (Bowen, 1997). The riparian vegetation of streamflow in Duffins Creek and therefore also shades the stream and thus helps to control plays an important role in maintaining relatively stream temperature which influences some water good water quality and cool stream temperatures, quality measures (e.g., ammonia compounds, particularly in the upper headwater streams. dissolved oxygen). Three large regional aquifers, the upper, intermediate and lower, underlay the watershed The combination of these physical and biological and discharge groundwater to the watercourse at features currently present in the Duffins various interception points. Figure 8 shows that watershed provides an additional form of water groundwater discharge is most significant in the quality protection. In rural, well forested and upper West and upper East Duffins Creek pervious catchments, less stormwater runoff is (Hinton, 1995). The source of this flow is likely generated during routine, small sized storms the upper aquifer. than in urbanized catchments (Bowen, 1997). 12 Figure 8 Relative per cent distribution of baseflow by subwatershed, Duffins Creek.

13 Therefore smaller volumes of suspended SANITARY SERVICING (sewage treatment sediment are generated during each storm and plants, communal servicing, septic systems) thus total annual loads of suspended solids There is one sewage treatment plant (STP) on the reaching the streams remain low. As forest cover Stouffville Creek tributary, the presence of which is removed and watersheds urbanize, the small has been observed to influence water quality sized storms (i.e. less than 5 mm), which conditions. The effect of the STP is evident by previously never affected streamflow, now examining the spatial distribution of chloride generate a greater quantity of runoff, possess levels throughout the watershed. Figure 9 greater erosive energy and produce greater illustrates the sharp increase in chloride levels in suspended sediment loads (Bowen, 1997). Since Stouffville Creek immediately downstream of the small storms occur more frequently than the STP while, upstream, the Stouffville tributary large events, urban streams are subjected to experiences very low levels (< 25 mg/L) typical increased duration and frequency of elevated of normal river water. Chlorides arise primarily levels of suspended solids. from road salt associated with urban stormwater runoff, domestic uses, as well as septic fields The importance of these natural features to the and landfills. Chlorides, therefore, are a general hydrology and water quality of the Duffins indicator of human disturbance. Similar patterns Creek was not always recognized. Much of the are observed for phosphorus and faecal upper watershed area was cleared for agriculture coliform bacteria. in the 1800s, however poor farming conditions and erodible soils provided the impetus for A study of surface water quality for the Seaton reforestation programs since the 1940s. Significant land area also found several water quality portions of these sensitive areas have since been parameters (phosphorus, chloride and faecal acquired and brought into public ownership coliform bacteria) were greatest downstream of where they can be protected in perpetuity. the STP (Geomatics et al., 1991). There is However, there is a need to ensure that currently a plan under way to decommission this appropriate management approaches are in place STP and re-direct servicing to the Duffins Creek to protect the remaining areas on private lands. Water Pollution Control Plant on the waterfront. It is expected that the surface water quality will Land Use Activities improve after the STP is decommissioned.

Land use activities can modify watershed Septic systems are utilized in the rural portions of landscapes and introduce a source of pollutants. the watershed. When improperly located, This will have an impact on surface water quality. constructed or poorly maintained, there is the Currently, the principle land uses in the potential for contaminants to leach to ground watershed consist of rural/agricultural throughout and surface water. Septic systems are a source of the mid reaches, rural estate in the headwaters, chlorides, nitrates and bacterial contamination. urban in the town of Stouffville in the upper There are occasionally pressures for communal northwest portion of the watershed and in servicing schemes in rural areas to allow greater Pickering to the south along with several small development densities than would be possible villages and a few golf courses. The Stouffville using individual septic systems. The Region of sewage treatment plant is responsible for the Durham policy currently permits communal most significant adverse influence on stream water systems only where existing septics are failing. quality, followed by urban and agricultural runoff. Other factors influencing water quality arise from STORMWATER RUNOFF spills, illicit discharges, golf courses, landfills, pet As urbanization occurs, soil compaction and and wildlife faeces, atmospheric deposition and paved surfaces increase the imperviousness of the potentially in the future, an airport. watershed which acts to generate a greater 14 Figure 9 Duffins Creek Chloride Levels and Land Use 15 volume of stormwater runoff to the creek. The road salt and are also an indicator of the presence resulting increase in stream discharge can scour of other pollutants. Elevated chloride levels in the creek bed and incise the channel banks. This Toronto area watersheds also correlate well with erosive activity generates a significant source of observations of degraded aquatic systems suspended sediment loads to the creek. A variety (Bowen and Hinton, 1988; Mayer et al., 1999). of pollutants are transported in stormwater runoff, including suspended sediment, nutrients, Stormwater runoff passes through storm sewers chlorides, bacteria, metals and synthetic organic or drainage ditches. Along most roadways and in chemicals. These pollutants arise from many the older urban areas of Stouffville and sources in rural estate and urban landscapes and Pickering, this drainage travels directly to are described in subsequent sections. streams, untreated. Since the 1980s, stormwater management measures have been employed in In urbanizing areas, stormwater runoff and the new developments to manage runoff quantity. associated pollutants have increased in the Since 1990, developments have also incorporated streams over time. This is evident by examining stormwater management facilities with a water the relationship between trends in annual quality control component to reduce the volume average daily traffic and stream chloride of pollutants in stormwater runoff. The Duffins concentration in the lower Duffins Creek over watershed currently has approximately 25 the last few decades (Figures 10 and 11). Traffic stormwater ponds built and/or in the planning densities are an indication of highway expansions stages. At source controls of pollutants will also and improved levels of road maintenance. help improve water quality. Chloride levels, for Chlorides originate from de-icing chemicals like example, may be reduced by applying improved

Figure 10 Average Daily Traffic, 1978-1992 16 Figure 11 Median Annual Chloride Concentration Over Time - Bayly Street salting practices designed to maintain safe road are low and low-medium, respectively. Fertilizer conditions and minimize the application of salt. availability to contribute to water quality The improved practices thus reduce the amount problems varied depending on the tillage of chloride reaching the watercourse through practices employed on the farms. These data stormwater runoff. In the case of chlorides, at would suggest that farm practices, in addition to source management measures are the most the STP, are a significant cause of excessive effective because stormwater management stream phosphorus levels. facilities are not able to remove them very well due to their soluble nature. The Stormwater The Rural Clean Water Program, administered chapter of this State of the Watershed report by TRCA, is a remedial action program designed offers a more in-depth discussion of water quality to improve local water quality in rural areas. The issues pertaining to Stormwater. program is designed to educate land owners about rural water quality issues and provide RURAL/AGRICULTURAL ACTIVITIES technical and financial assistance to improve Agricultural areas represent a potential source of management practices and mitigate the levels of pollutants (e.g., suspended sediment, phosphorus, bacteria and nutrients entering watercourses. bacteria, pesticides) if proper practices are not Other management approaches undertaken in employed. For example, Hill (1981) found that the Duffins watershed occur on federally owned phosphorus concentration in the Duffins Creek lands, where rural best management practices tended to be higher in catchments with a greater are promoted by Transport Canada. area under crop cover. A fertilizer use survey in the Stouffville and Reesor Creeks (Eddie, 1998) SPILLS AND ILLICIT DISCHARGES found that a variety of nitrogen and phosphorus Deliberate discharges or accidental spills are materials are used in the agricultural areas. especially prone to occur in densely urbanized Application rates for phosphorus and nitrogen areas, particularly in industrial areas and 17 transportation corridors. Analyses undertaken as of municipal or domestic wastes. Some sites closed part of the Toronto Area Watershed Management as early as 1940 (MOEE, 1991), with the last site Studies suggest that a petroleum spill of 100 closing in the late 1990s. Historical records of litres may be as toxic to aquatic biota as combined landfill sites vary considerably in the amount of sewer overflows or stormwater runoff and that the information available about the site and its frequency of occurrence may be of more concern operation. The locations of many of the closed than the actual magnitude of a spill. Data on the landfill sites in the Duffins Creek watersheds are frequency and type of spills to Duffins Creek known, however it is not known whether or not cannot specifically be extracted from the Ministry they are contributing leachate to ground or of the Environment (MOE) spills database at surface water systems. To date, no studies have present, however it is estimate that there could shown an impact due to the abandoned landfill be in the order of eight spills per year, based on sites near Ganatsekiagon and Urfe creeks. The total spills to water data for Pickering and Ajax. most recently closed landfill site, Brock West, continues to be actively monitored by the City of Businesses and municipalities that adopt Toronto. Investigations into the impacts of environmental management standards (i.e. ISO landfills on ground and surface water quality are 14000) focus on pollution prevention and have a usually conducted on an as needed basis. To date, plan in place to deal with unexpected spills. no problems have been found. If a problem is detected through monitoring, then remedial GOLF COURSES actions will be taken. This specialized land use can contribute increased loadings of nutrients and pesticides to A FUTURE AIRPORT a watercourse if proper practices are not The 7,530 hectares of land in the Duffins Creek employed. Some golf courses also rely on surface watershed, designated as the Pickering Airport and ground water as a source of irrigation and Lands, was assembled in 1972 by the Government therefore are particularly concerned over the of Canada for a future airport. Presently, the protection of good water quality. Many golf courses parcel of land is predominantly in rural land use, are adopting environmental management plans with occasional woodlots and a number of prepared specifically for their properties. By stream corridors. Until such time as the land preparing these plans, the courses can become undergoes alteration for airport construction, certified under the Audubon Sanctuary Program water quality is expected to remain good. for golf courses, which aims to reduce pesticide use and negative environmental impacts. Management approaches to protect the surface water quality of the airport lands currently A fertilizer use survey conducted in the include the Rural Outreach Program, promoted Stouffville and Reesor Creeks subwatersheds by Transport Canada on the farms rented on the (Eddie, 1998) found nitrogen and phosphorus airport lands. If and when future airport fertilizer application rates on golf courses as construction begins, environmental assessment average to high (110 - 225 kg/ha), although procedures will be followed. In addition, fertilizer availability to contribute to water Transport Canadas Sustainable Development quality problems at the time of storm runoff was Strategy initiated in 1997, is intended to characterized as low due to the slow release integrate environmental sustainability with the feature of the products used in these settings. traditional themes of safety and efficiency.

LANDFILLS PET AND WILDLIFE FAECES There are six closed landfill sites in the Duffins Pet and wildlife faeces can represent a significant Creek watershed, plus one along the waterfront. source of bacteria to urban waters. It is estimated Most of these sites were operated for the disposal that there are approximately 3,000 dogs living in 18 the City of Pickering (Koch, 2001), the most Air quality is affected by local, national and urbanized area in the Duffins Creek watershed. international sources of pollution. Generally air These dogs generate the equivalent daily faecal quality has improved in Ontario over the past 25 output of 1,000 humans. It is interesting to note years, however, there are increasing problems that under current regulations a community of with ground level ozone and suspended that size would be required to have a communal particulates. Of these pollutants, particulates are sewage treatment system to manage the waste. of most concern to water quality. Particulates are created by industrial processes and are present in In urbanizing areas, pet stoop and scoop by- motor vehicle exhaust. Further discussion on air laws and dont feed the geese awareness quality within the Duffins Creek watershed is programs help reduce bacteria loadings. provided in the Air Quality chapter.

ATMOSPHERIC DEPOSITION Atmospheric sources of various pollutants can become relatively more significant as a watershed urbanizes. This is due to the larger areas of impervious surfaces in an urban area and the stormwater conveyance systems that collect and convey pollutants to watercourses. A local Toronto outfall monitoring study (DAndrea et al., 1993) found no significant difference in stormwater quality for most parameter between drainage areas of different land use types (e.g., industrial, residential). This finding may be explained by a common atmospheric source of pollutants.

Vehicle emissions may be a relatively significant source of certain pollutants. A study characterizing the sources of polycyclic aromatic hydrocarbons (PAHs) in street and creek sediments noted the significance of vehicle emissions relative to other industrial sources. Most of the PAHs in vehicle emissions are deposited on the street/road grid itself or within 40 metres either side of the road (Sharma et al., 1997). Stormwater runoff conveys pollutants directly to drainage systems without opportunity for filtration as might occur with particles deposited on vegetated surfaces.

19 Summary

Duffins Creek has very good water quality conditions overall. In fact, conditions are among the best of all other Toronto Region watercourses! Similar to other streams subject to urban and agricultural runoff, the western and lower branches of the creek contain elevated levels of nutrients, bacteria and chlorides. A sewage treatment plant, which discharges to the Stouffville Creek branch of the upper West Duffins Creek, is also responsible for a significant portion of these contaminant loadings. Bacteria levels pose some limitations on swimming or water contact recreation. Dissolved oxygen levels immediately downstream of the Stouffville Sewage Treatment Plant and in the Urfe Creek may occasionally be limiting for aquatic life. Otherwise, water quality does not generally pose concern for human health or aquatic communities.

While the Stouffville Sewage Treatment Plant and urban and agricultural runoff represent the primary human factors controlling water quality, the natural features of the Duffins watershed are especially conducive to good water quality. The predominance of sandy soils and extensive forest cover and wetlands in the upper West and East branches of Duffins Creek promote infiltration and reduce stormwater runoff, a major delivery mechanism of pollutants to the watercourse. Groundwater discharge makes up a significant portion of stream flow and therefore helps maintain cool temperatures and good water quality throughout much of the creek.

In order to protect the good water quality conditions in Duffins Creek, management activities should focus on maintaining control over the quality of effluent from the existing sewage treatment plant operations. This should occur until such time as it is decommissioned, employing rural best management practices, urban stormwater management, riparian habitat protection and enhancement and groundwater protection.

20 References

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Bowen, G.S., 1997. Water Quality Assessment of Duffins Creek, Focussing on Streams Draining the North Pickering Development Corporation Lands. 30p.

Bowen, G.S. and M.J. Hinton, 1998. The Temporal and Spatial Impacts of Road Salt on Streams Draining the Greater Toronto Area. In Proceedings of the Groundwater in A Watershed Context Symposium, December 2-4, 1998. Canadian Water Resources Association.

Boyd, D., 1999. Assessment of Six Tributary Discharges to the Toronto Area Waterfront, Volume 1: Project Synopsis and Selected Results. Ontario Ministry of the Environment. Prepared for The Toronto and Region Remedial Action Plan.

Boyd, D., M. DAndrea and R. Anderton, 1999. Assessment of Six Tributary Discharges to the Toronto Area Waterfront, Volume 2: Technical Appendix and Data Summary. Ontario Ministry of the Environment. Prepared for The Toronto and Region Remedial Action Plan.

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Hill, A.R., 1981. Stream Phosphorus Exports from Watersheds with Contrasting Land Uses in Southern Ontario. Water Resources Bulletin 17(4): 627-634.

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Ontario Ministry of the Environment, 1999. Guide to Eating Ontario Sport Fish 1999-2000. Queens Printer for Ontario.

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Ontario Ministry of the Environment, 1991. Waste Disposal Site Inventory. Queens Printer for Ontario.

Petro, S., 2000. Young-of-the-Year Fish Database Update for the Duffins Watershed. Ontario Ministry of the Environment.

Regional Municipality of Durham Health Department, 1999. E. coli bacteria data for waterfront beaches in Durham Region, 1997-1999. 22 Sharma, M., E.A. McBean and J. Marsalek, 1997. Source Characterization of Polycyclic Aromatic Hydrocarbons in Street and Creek Sediments. Water Quality Resources Journal 32(1): 23-35.

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Toronto and Region Conservation Authority, 1999. State of the Watershed Report: Highland Creek Watershed. Downsview, Ontario.