Humber River
State of the Watershed Report -
Surface Water Quality
2008
Humber River State of the Watershed Report – Surface Water Quality
EXECUTIVE SUMMARY
• The lower reaches of streams in the West Humber with its clay soils, low baseflow rates and urbanizing landscape exhibit the poorest overall water quality in the Humber River watershed. Conditions at the mouth of Black Creek and at the Old Mill station on the Lower Humber are not much better. The absence of modern stormwater management controls in the older urban developments upstream of these stations contributes significantly to the dirty water at these sites. TRCA, in partnership with municipalities, has identified stormwater retrofit opportunities in these areas to help address this issue;
• Surface waters in the upper portions of the watershed on Cold Creek, Centreville Creek and on the Upper Main Humber display reasonably good water quality. Even the East Humber, which has experienced moderate levels of urbanization over the past 10 years, remains relatively clean;
• The concentration of suspended solids in surface waters is a particularly important water quality indicator because solid particles act as a primary transport vector for other contaminants such as phosphorus, most heavy metals, and bacteria. Levels of suspended solids were highest in the West Humber, where erodible clay soils predominate, followed by the Lower Humber at Old Mill. Options available to reduce suspended solid concentrations include vegetated riparian buffers and restrictions on cattle access in rural areas, improved sediment controls on construction sites in urbanizing areas, and enhanced management of stormwater in cities and towns. The key is to reduce the volume of stormwater that runs off into streams by infiltrating as much of it as possible;
• Bacteria levels in the rivers often failed to meet the provincial guideline for recreational swimming, even on streams dominated by natural and rural land uses. For instance, only 29% of samples collected in the mostly rural Centreville Creek subwatershed met the guideline. The highest concentrations were observed in the City of Toronto and on the West Humber;
• All Humber watershed swimming beaches were unsafe during most of the swimming season in 2004, with the exception of Albion Hills, which chlorinates the enclosed beach area in order to keep the beach open. The three Toronto waterfront beaches were closed most frequently, in large part due to their close proximity to the mouth of the Humber River, which is a source of significant bacterial contamination. Year-to-year variations in beach posting frequency primarily reflects the frequency, duration and intensity of rain storms occurring in any given year;
• The benefits of stormwater management in reducing bacteria levels at Toronto waterfront beaches was modelled as part of the City of Toronto’s Wet Weather Flow Management Master Plan in 2003. Results indicated that even with aggressive new stormwater controls in the City, the waterfront beaches would remain closed for most of the swimming season. Improvements could be achieved only if waterfront sources of beach contamination are addressed (e.g., combined sewer overflows) and upstream municipalities commit to a similarly aggressive approach to improving stormwater controls;
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EXECUTIVE SUMMARY (continued)
• The somewhat stringent provincial objective for phosphorus in receiving waters was rarely met anywhere in the Humber. Elevated levels in part reflect the limited capacity of current stormwater ponds and other end-of-pipe stormwater management facilities to remove this constituent. Even during dry weather, effluent concentrations from stormwater ponds and wetlands are typically at least double the provincial water quality objective for phosphorus. Stormwater infiltration practices such as permeable pavement and underground perforated pipe systems are much more effective in reducing phosphorus loads but to date, there are very few instances in the Humber River watershed where these types of practices have been implemented;
• Chloride is a major constituent of de-icing salts applied to roads during the winter. Chloride levels in the Humber River are rising due to increasing urbanization. Winter levels in the Lower Humber, West Humber and Black Creek are often above the threshold established to protect aquatic life. The highest median values were recorded at the mouth of the Black Creek subwatershed which is fully urbanized. At this station, only 38% of samples collected were below the 250 mg/L limit. Further downstream, at the Old Mill station, 67% of samples collected met the guideline and in all areas north of Steeles, over 90% of samples met the guideline. A leveling off of chloride levels in Humber streams may be expected in the future as municipal salt management plans, developed in 2004, begin to take effect. Alternatives to road salts will need to be considered on local roads if significant reductions in chloride levels are to occur;
• Organic and inorganic chemicals entering watercourses through spills or accidental discharges are controlled by federal, provincial and municipal governments through a complex array of regulations and programs. The large number of spills that continue to occur in the GTA suggest that still more could be done in this area. Between 1988 and 2000, there were approximately 900 oil spills and 750 chemical spills in the Humber River watershed, of which roughly half drained to the Humber River or one of its tributaries. In terms of volume, the chemical, transportation and general manufacturing sectors contributed the most to chemical spills, often as a result of container or fuel tank leaks. Actions that would help to address this problem include better spill prevention programs, improved structural controls on spill prone areas, stronger penalties for violations and stepped-up enforcement of existing laws;
• Trends in water quality were assessed for copper, zinc, total suspended solids, chloride and phosphorus at the Old Mill Station on the Lower Humber. Chloride was the only one of the five variables analyzed that showed an upward trend. These data suggest that stormwater management controls in newly developed areas do appear to be effective in removing contaminants associated with suspended sediment, such as copper, zinc and phosphorus. If they were not, Humber water quality would have been expected to deteriorate with steady growth of the urban footprint in the watershed since the early1980s.
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TABLE OF CONTENTS
1.0 INTRODUCTION...... 1 2.0 UNDERSTANDING THE FACTORS AFFECTING SURFACE WATER QUALITY ...... 1 3.0 MEASURING SURFACE WATER QUALITY...... 4 4.0 EXISTING CONDITIONS...... 8 4.1 Swimming and Body Contact Recreation: The Bacterial Indicator ...... 8 4.2 Conventional Contaminants: the Aquatic Health Indicator...... 10 4.3 Organic and Metal Contaminants: the Chronic Effects Indicator...... 16 4.4 Water Quality Trends in the Humber River Watershed...... 25 4.5 Other Issues: Spills, Landfills, Sanitary Servicing, Golf Courses ...... 27 5.0 SUMMARY AND MANAGEMENT CONSIDERATIONS ...... 29 6.0 REFERENCES...... 32
LIST OF FIGURES
Figure 1: Water Quality and Fish Tissue Monitoring Stations...... 6 Figure 2: Percent of Samples that Meet Guidelines for E.coli and Conventional Variables... 12 Figure 3: Percent of Samples that Meet Guidelines for Selected Trace Metals...... 22 Figure 4: Trends in Annual Median Concentrations of Chloride, TP, TSS, Copper and Zinc at Old Mill Station (Lower Humber)...... 26
LIST OF TABLES
Table 1: The Environmental Effects and Sources for Key Water Quality Variables...... 5 Table 2: Data Sources, Locations and Period of Record...... 7 Table 3: Humber River E.coli Levels and Humber Beach Postings ...... 9 Table 4: Percent of Time Selected Conventional Pollutants Met Guidelines at Humber River Monitoring Stations (2002 - 2004) ...... 11 Table 5: Wet Weather Concentrations During the Warm Season (1996 to 2004)...... 15 Table 6: Levels of Canada-Ontario Agreement ‘Tier 1' Contaminants in the Lower Humber River at Old Mill station...... 18 Table 7: Levels of Poly-Aromatic Hydrocarbons (PAHs) Sampled in the Lower Humber River at the Old Mill Station...... 19 Table 8: Percent of Samples that Met Guidelines for Selected Trace Metals at Humber River Monitoring Stations (04/02 - 02/04)...... 21 Table 9: Young-of-the-Year Fish Sampling Locations Where Fish Tissue Guideline Exeedances Occurred...... 23 Table 10: Sportfish Consumption Advisory Limits 1 for Sites in the Humber Watershed...... 24
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1.0 INTRODUCTION
In 1997, the Humber Watershed Task Force released the Humber River Watershed Strategy, Legacy: A Strategy For A Healthy Humber (MTRCA, 1997a), which provided thirty objectives for a healthy, sustainable watershed, and a set of actions necessary to achieve them. It also provided an overview of the state of the Humber River watershed at that time. Since the release of the watershed strategy, a significant amount of new information has become available through monitoring, special studies and the experiences of watershed partners.
In 2004, the Toronto and Region Conservation Authority (TRCA), in partnership with watershed municipalities and the Humber Watershed Alliance initiated a study to develop an integrated watershed management plan for the Humber River. This study was initiated to fulfill the watershed planning requirements of the Oak Ridges Moraine Conservation Plan , 2002, and to update the strategies and recommendations of Legacy , in light of new information, a stronger scientific foundation and better understanding of the effects of human actions on natural ecosystems. The watershed plan is intended to inform and guide municipalities, provincial and federal governments, TRCA, non-governmental organizations and private landowners regarding management actions needed to maintain and improve watershed health.
This State of the Watershed Report provides updated information on current conditions, emerging trends and identifies key watershed management issues and opportunities in the Humber pertaining to surface water quality. Indicators of watershed health and associated targets are used to rate current conditions. Ratings for a full suite of indicators of watershed health are summarized in, Listen to Your River: A Report Card on the Health of the Humber River Watershed (TRCA, 2007).
This State of the Watershed report also provides an overview of current management strategies and introduces some innovative approaches to address key issues, which will be considered for inclusion in the Humber River Watershed Plan . It begins with an overview of factors that influence watershed conditions and the indicators being used to track current conditions and evaluate watershed health.
2.0 UNDERSTANDING THE FACTORS AFFECTING SURFACE WATER QUALITY
Natural Influences
Geology has a significant effect on water quality, through rock and soil characteristics as well as through its influence on groundwater recharge and discharge rates. High rates of groundwater discharge into streams translate into larger baseflows, cooler stream temperatures and typically cleaner surface water during dry weather. The cooler temperatures maintain higher oxygen levels and create a less favourable environment for deleterious bacteria to grow.
In the Humber watershed, the major recharge areas are associated with relatively permeable soils on the Oak Ridges Moraine and Iroquois Sand Plain. These features facilitate infiltration, resulting in lower rates of overland runoff. As the infiltrated runoff moves through the soil, most pollutants are filtered or immobilized, providing a relatively clean source of water when it
Humber_SW_Quality_FINAL_062408F.doc 1 Humber River State of the Watershed Report – Surface Water Quality eventually re-emerges in a stream or lake. By contrast, fine-grained clay and clay loam soils that characterize the Peel Plain have low infiltration capacity and are highly erodible . The low infiltration rates promote soil erosion by facilitating overland runoff . Areas with these types of soil often act as sources of sediment and associated contaminants, and therefore do not promote good surface water quality.
Riparian buffers play an important role in reducing the quality of overland runoff from erodible soils, steeply sloping land and poor land use practices on adjacent streams and wetlands. This result is achieved by both grassed and forested buffers through filtration of sediment and associated contaminants, vegetative uptake of soluble nutrients, and infiltration of overland runoff from surrounding fields and hillslopes. Removal of over half the phosphorus, nitrogen and sediment inputs is typically achieved within the first 15 m of buffer width (Osborne and Kovacic, 1993; Castelle et al ., 1994). Woody riparian vegetation also helps to stabilize banks and moderate stream temperature by providing shade.
Wetlands, with their natural ability to store water and absorb nutrients during the growing season, have a significant effect on water quality as well. They help to reduce peak flows, maintain natural hydrological conditions and play an important role in regulating sediment and nutrient exchange within the river system (Mitsch and Gosselink, 1993). Like riparian buffers, wetlands filter the water, with considerable benefits to water quality.
Influences in the Rural and Urban Landscape
Farms can be significant ‘non-point’ sources of sediment, nutrients, bacteria and pesticides to rivers if appropriate management practices are not followed. Decisions on cropping methods, manure storage and animal fencing for example, all have profound implications to the water quality of adjacent river systems. Septic systems, which are rarely monitored, can also contribute pollution to streams through runoff overland if they are not appropriately maintained (Schueller, 1999). Groundwater can also be contaminated by failing septic systems, which is of particular significance in rural areas where residents are often dependent on wells for their drinking water.
Nutrients, bacteria, sediment and pesticides are the most common pollutants in runoff from agricultural catchments. Sources include synthetic and organic fertilizers applied to crops, pest control practices, livestock manure storage, cattle entry to streams and soil erosion. Management of these pollutants typically involves creating vegetative or structural barriers between the farm and stream, and engaging natural or biological processes to reduce, convert or store pollutants on the land before they reach the stream. Some practices, such as maintaining a well aggregated top soil layer through conservation tillage, provides multiple benefits in terms of improved productivity, better water retention, lower input costs, as well as reducing the release of harmful pollutants. Financial and technical assistance to rural landowners willing to undertake on-farm pollution management activities is made available through TRCA’s Rural Clean Water Program.
Pollution levels vary substantially with stream flow rates and volumes. These variations reflect differences in sources between dry and wet weather. Dry weather flows originate primarily from groundwater, which has been filtered by the soil and is typically less contaminated than surface runoff. In urban areas, the groundwater component of dry weather flow may be
Humber_SW_Quality_FINAL_062408F.doc 2 Humber River State of the Watershed Report – Surface Water Quality augmented by industrial cooling water, lawn watering, vehicle washing, swimming pool discharge to storm sewers, illegal sanitary connection discharges and accidental or deliberate spills to roadside catchbasins (Snodgrass and D'Andrea, 1993). Rural area sources of dry weather flow may include excess crop irrigation, septic system drainage, or barnyard cleaning, although these would normally influence surface water levels only indirectly by increasing groundwater recharge.
The majority of wet weather runoff in urban areas cannot infiltrate due to the prevalence of impervious surfaces. Instead, the wide variety of contaminants that accumulates on impervious surfaces during dry weather are washed off and transported through roadside ditches and sewer networks to watercourses. This fast-flowing water picks up bacteria from wildlife and domestic pet faeces, nutrients and pesticides from lawn and garden maintenance, toxic chemicals from industrial sites and a wide range of contaminants associated with transportation land uses, including heavy metals, oil, grease, road salts and hydrocarbons. Atmospheric sources of pollutants, such as, particulate matter and polycyclic aromatic hydrocarbons (PAHs) can be relatively more significant in urban areas than rural, due to nearby sources and the large area of impervious surface available to capture these pollutants. The ‘flashy’ stream flows associated with urban surfaces increase channel erosion, which adds to the levels of suspended solids and turbidity in the river system .
Traditionally, stormwater runoff in urban areas has been ‘managed’ by constructing curb and gutter storm drain networks that convey this runoff quickly and efficiently to receiving streams. Stormwater controls were designed primarily to prevent flooding of developed areas. Over the past two decades, this traditional approach to stormwater management has broadened to include considerations of water quality and downstream erosion control. Plans to retrofit old quantity control dry ponds to larger quality control wet ponds have now become a standard feature of municipal stormwater management strategies. The City of Toronto’s Wet Weather Flow Management Plan exemplifies this new and evolving approach to stormwater management in recognizing rainwater and snowmelt as a resource and adopting a treatment train approach that emphasizes source control measures first, followed by conveyance and end-of-pipe controls (City of Toronto, 2003a).
Despite these advances in stormwater management, there remain several challenges to managing wet weather flow impacts in urban areas. While stormwater ponds have multiplied in recent years, studies in the United States report that structural end-of-pipe controls such as ponds and engineered wetlands are not sufficient to safeguard the geomorphic integrity of streams and the health of downstream aquatic communities (Stribling et al ., 2001; Maxted, 1999), although they contribute significantly to improved water quality (MWCG, 1995). The aquatic impacts appear to be related to post development changes in flow regime, increases in stream temperature and inadequate sediment control associated with construction. Further, end-of-pipe controls are not designed to remove road salts and other soluble pollutants, which can present serious threats to the health of aquatic life (Environment Canada and Health Canada, 2001).
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3.0 MEASURING SURFACE WATER QUALITY
Surface water quality contaminants are typically grouped according to their management implications into bacteria, nutrients (nitrogen and phosphorus compounds), metals, conventional pollutants (e.g., suspended solids, chloride) and organic compounds. Elevated levels of bacteria can affect human health and the recreational uses of a water body. Conventional pollutants and nutrients are assessed with regard to the protection of aquatic life and other issues such as aesthetics. Key conventional water quality and bacterial pollutants were selected for evaluation based on their importance to common water use concerns. The environmental effects and sources of these pollutants are presented in Table 1.
Heavy metals and organic pollutants are detrimental to aquatic life, but also affect human health through consumption of sport fish and bio-accumulation in the food chain. Synthetic organic chemicals, such as those found in pesticides and pharmaceutical products, can also find their way into the environment through, for example, septic and sewage treatment plant effluent. They can even enter our drinking water, if they are not among the suite of chemicals tested and targeted for treatment in drinking water treatment plants. Research has demonstrated the adverse effects of these contaminants on endocrine disruption and hormone levels in animals and there are ongoing investigations into potential effects on human health. Metals and organic pollutants are discussed as a separate category in this report because they can have adverse effects even at very low concentrations in surface waters.
The locations of water quality and fish tissue monitoring stations are shown in Figure 1. Table 2 lists the sources of data used in this assessment. The majority of water quality data characterizing current conditions in the Humber River watershed was collected under TRCA’s
Regional Watershed Monitoring Network ambient water sampling program (1999 to 2004) and the Ontario Ministry of the Environment’s (OMOE) tributary toxics dry/wet weather sampling program (1991/92, 1997/8). The OMOE program focuses primarily on organic compounds identified as priority pollutants under the Canada-Ontario Agreement. Historical trends in water quality are based on sampling data collected since the early 1980s by the OMOE at the Old Mill station on the Lower Humber.
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Table 1: The Environmental Effects and Sources for Key Water Quality Variables. Variable Effect Source
Total Elevated concentrations reduce water clarity, which can inhibit TSS originates from areas Suspended the ability of aquatic organisms to find food. Suspended of soil disturbance, Solids (TSS) particles may also cause abrasion on fish gills. As solids settle, including construction sites course rock and gravel spawning and nursing areas become and farm fields, lawns, coated with fine particles, limiting the ecological function of gardens, eroding stream these important areas. Many pollutants are readily adsorbed by channels, and grit suspended solids, and may become available to benthic fauna accumulated on roads. when deposited. Buildup of sediments influences the frequency of method of dredging activities in harbours and reservoirs. Phosphorus is essential to the growth and survival of organisms. Sources include lawn and Phosphorus However, oversupply of this nutrient promotes eutrophication of garden fertilizers, eroded surface waters by stimulating nuisance algal and aquatic plant soil particles, sanitary growth, which deplete oxygen levels as they decompose sewage, animal wastes and resulting in adverse impacts to aquatic fauna and restrictions on decaying plant material. recreational use of waterways. Excessive nitrate (NO -N) can encourage nuisance algae growth Nitrate originates from Nitrate 3 and lead to eutrophication in aquatic environments (and the agricultural and residential degradation of aesthetics). Nitrate has also been shown to exert application of fertilizer, chronic toxic effects in amphibian species at relatively low animal wastes, sewage and concentrations. decaying plant material. Un-ionized ammonia is a form of nitrogen that is toxic to aquatic Ammonia is a natural Un-ionized life at low concentrations. It is influenced by temperature and constituent of human and Ammonia pH. animal sewage, and also forms from the microbial decomposition of organic tissue. Chloride levels influence the quality of irrigation water, and the The largest source of Chloride aesthetics and taste of drinking water. Elevated levels may also chloride is from road salt harm aquatic life. Background concentrations in natural surface application during the waters are typically below 10 mg/L. winter months. Dissolved oxygen levels fluctuate naturally in response to Oxygen levels are depleted Dissolved physical mixing, salinity, temperature, and biological activity by bacterial respiration Oxygen (DO) (e.g. plant photosynthesis). Low dissolved oxygen levels lead during the decomposition to stress responses in aquatic organisms, and increase the of organic matter at the toxicity of some metals and organic compounds (e.g. lead, sediment-water interface. copper, cyanide). The presence of Escherichia coli in surface water is indicative of Bacterial sources include E. coli loadings of faecal matter of either animal or human origin. illegal sewer connections Elevated levels can result in restrictions on the recreational use and inputs from wildlife and of water bodies. domestic animals.
Humber_SW_Quality_FINAL_062408F.doc 5 Figure 1: Water Quality and Fish Tissue Monitoring Stations Humber River State of the Watershed Report – Surface Water Quality
Table 2: Data Sources, Locations and Period of Record Data Sources Monitoring Period of Water Quality Comments Station(s) Record Groups
Regional Water 9 stations; 4 on the 1999 - 2002 conventional, Routine monthly grab Quality Monitoring Main, 1 on the nutrients, samples - biased Network Lower Humber, 2 on metals, bacteria towards dry weather the West, 1 on the East, 1 on Black Creek
Provincial Water 1 station at Old Mill Historical conventional, Routine bi-monthly Quality Monitoring on the Lower data nutrients, grab samples - Network Humber metals, bacteria biased towards dry weather
Beach Sampling 4 beaches along the swimming Beach postings Postings based on Programs (Peel, Toronto waterfront season geomean of E. coli in York, Toronto) and 2 inland 1997 - 2003 5 samples beaches 2001/02 and 1991/2: 2000 - 2001; Lake Ontario Conventional, Monthly composites Tributary Toxics 1 stn near the mouth 1991 - 1992 metals, organic in 2000/2001. Monitoring Program compounds 24 hour time- integrated composite samples in 1991/92
MOE Guide to Grenadier Pond, 2003 Mercury, PCBs, Adult fish tissue Eating Ontario Sport Queensway Marsh, mirex and analysis Fish in and below pesticides Clairville Reservoir, North of Bolton, Lake Wilcox.
MOE Young-of-the- 5 stations; 1 each on 2002 Organic Young-of-the-year Year Fish Monitoring Black Creek, East compounds fish tissue analysis and West Humber and 2 on the Lower Humber.
Tissue analyses of young-of-the-year fish and sport fish from the Ministry of the Environment’s Young-of-the-Year and sport fish contaminant programs (2003) were used as an indication of the presence of organic contaminants or metals in biologically available forms.
The water quality implications of oil and chemical spills, landfills, septic systems, and golf courses require further study. A qualitative assessment of these issues follows the quantitative discussion of water quality in the Humber River.
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4.0 EXISTING CONDITIONS
The Humber River headwater tributaries are predominantly fed by clean groundwater arising from permeable loam and sandy loam soils of the Oak Ridges Moraine. The quality of this groundwater input is important, as it comprises over one third of the total baseflow in the Humber River. Similarly permeable soils appear again along the Main Humber River reaches, and in the lower portions of the watershed, as part of the Iroquois sand plain. Lower rates of groundwater discharge are associated with the less permeable Peel clay plain soils in the middle portion of the watershed (especially the East and West Humber), which adversely affects the quality of dry weather flow in these areas.
The marsh at the mouth of the Humber River helps to purify river water before it enters Lake Ontario. Other wetlands in the Humber River watershed are concentrated mostly within the headwaters of the Main and East Humber subwatersheds (see Figure 1). Headwater wetlands can improve water quality by filtering contaminants and attenuating peak flows (Mitsch, 1992). Unfortunately, most of the wetlands in the watershed have been drained, cleared and filled for farming and other uses and those that remain are under stress as a result of urban expansion, agricultural practices and other human activities.
In 2002, approximately 27% of the Humber watershed was classified as urban. Since the mid- 1990s, new developments have been required by municipalities to implement stormwater quantity and quality controls and, where applicable, drain roof runoff to grassed areas surrounding the building. As a result, approximately 19% of the urban area has stormwater controls with quantity and quality functions. The remaining 81% of the urban area consists of older developments in Toronto, Richmond Hill, Vaughan, King, Brampton and Caledon, of which 92% have no controls and 8% have quantity control only. The quality of water downstream of these areas would, of course, be expected to be more degraded than elsewhere in the watershed, especially in urban areas served by storm sewers. TRCA, in partnership with municipalities, have identified stormwater retrofit opportunities in older areas to help address this issue.
4.1 Swimming and Body Contact Recreation: The Bacterial Indicator
Escherichia coliform ( E.coli ) is the form of coliform bacteria used in Ontario to indicate the presence of harmful bacteria in surface waters. The Provincial Water Quality Objective (PWQO) for E.coli is 100 CFU/100 mL for swimming areas. The Toronto Stage 2 Remedial Action Plan goal is for lake water to contain less than 100 CFU/100 mL for 95% of the swimming season (WRT, 2002).
Three beaches on the waterfront and two beaches inland are monitored and posted when bacteria exceed safe levels for swimming. Bacteria levels at nine (9) river monitoring stations (see Figure 2) along with posting frequencies at the beaches are presented in Table 3. At all of the stations monitored for E.coli in the Humber River, less than 60% of samples collected met the provincial guideline during the warm season (May to November).
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The geometric mean concentrations of E.coli for the May to October monitoring period ranged from 89 CFU/100 mL at the Albion Hills station downstream of the confluence of Centreville Creek and the Main Humber (stn.83018) to 1444 CFU/100 mL near the outlet of the Black Creek subwatershed (stn.83012).
All of the beaches were unsafe during most of the swimming season, with the exception of Albion Hills, which chlorinates the enclosed beach area in order to keep the beach open. The three waterfront beaches were closed most frequently, in large part due to their close proximity to the mouth of the Humber River, which is a source of significant bacterial contamination. Year-to-year variations in beach posting frequency reflect the frequency, duration and intensity of rain storms occurring in any given year.
Table 3: Humber River E.coli Levels and Humber Beach Postings % of season safe for swimming*
% meet Monitoring Station Geo-mean Beach 1999 2000 2001 2002 2003 5 yr PWQO + E. coli avg. (CFU/100mL) + West Humber @ 238 15 Albion 100 100 100 100 100 100 Claireville Lake** 83002 East Humber @ 127 35 Lake Wilcox 8 97 81 100 55 68 Pine Grove 83004 Black Creek @ 1444 5 Ellis/ 87 5 13 33 21 32 Scarlett Road Windermere 83012 Main Humber @ 89 58 Sunnyside 34 30 24 49 35 34 Albion Hills 83018 Lower Humber @ 775 0 Boulevard 28 49 21 65 47 42 Old Mill 83019 Main Humber @ 154 50 Rutherford Road 83020 Main Humber, 200 29 Centreville Ck. 83104 West Humber @ 1402 0 Highway 7 83103 Main Humber, 135 57 Cold Ck. 83009 Sources: Regional Watershed Monitoring Program, City of Toronto Beach Sampling Program +Samples were collected from May to October. N=16-20 for each of the first 6 stations listed and N=7 for the remaining 3 stations. *Year-to-year variations in beach postings are influenced by variations in the intensity and frequency of rainfall events. ** The Albion Hills beach is chlorinated. Hence the beach is posted only when the chlorinator malfunctions.
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The benefits of stormwater management in reducing bacteria levels at the Humber beaches were modelled as part of Toronto’s Wet Weather Flow Management Master Plan. Results indicated that even with aggressive controls in the City of Toronto, the Lake Ontario waterfront beaches would remain closed for most of the swimming season. Improvements could be effected only if waterfront sources of beach contamination were addressed and upstream municipalities committed to a similarly aggressive approach to improving stormwater controls. Over 80% of the Humber River watershed is outside of the City of Toronto (City of Toronto, 2003b).
Rating for the Bacterial Indicator
The targets selected for meeting the surface water quality objective of managing the Humber River watershed for body contact recreation are provided below, along with a rating for existing conditions in the watershed. The two targets relate to conditions in the Humber River and conditions at the waterfront and inland beaches, respectively. The Humber beaches target is set at 70% as a first step towards meeting the Toronto Remedial Action Plan and WWFMMP goal for lake water to meet the E.coli guideline during 95% of the swimming season.
Objective: Protect and restore surface Overall Rating water quality with respect to toxic contaminants and other pollutants such as sediment, nutrients, bacteria and road salt Fail Indicator Measure Target Swimming and Escherichia coliform densities -Bacterial levels in surface water are body contact in water samples lower than 1990-96 levels. recreation -Beaches along the Lake Ontario shoreline are open more than 70% of the swimming season
An overall rating of ‘fail' for the bacterial indicator reflects high E.coli densities in the Humber River (i.e. less than 75% of sample concentrations met PWQOs), no improvement since the 1990-96 baseline period (TRCA, 2001), and ‘safe’ swimming conditions well below the 70% target at all three Humber waterfront beaches.
4.2 Conventional Contaminants: the Aquatic Health Indicator
Conventional pollutants were selected based on their relevance to common water use concerns. Their effects and sources were summarized in Table 1 earlier in the report. Data for existing conditions were collected and analyzed under the Regional Watershed Monitoring Network at nine (9) stations.
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The frequency that samples meet existing guidelines for selected conventional pollutants are presented in Table 4, and shown graphically in Figure 2. Values represent predominantly dry weather or low flow conditions in the Humber River. The impact of water temperature on aquatic life is assessed in relation to historical fish communities and thermal river reach designations in the Humber River State of the Watershed Report – Aquatic System (TRCA, 2008).
Table 4: Percent of Time Selected Conventional Pollutants Met Guidelines at Humber River Monitoring Stations (2002 - 2004) Subwatershed, Station Percent Meet Guideline Name, Station Number (number of samples) TSS Chloride Total Nitrate Un-ionized DO Phosphorus Ammonia
Main Humber, Cold Creek 90 100 62 100/100 100 100 83009 (n=21)
Main Humber, Albion Hills 95 100 71 100/100 100 100 83018 (n=21)
West Humber, Highway 7 48 100 10 71/90 100 100 83103 (n=21)
West Humber, Claireville 73 76 0 52/81 100 95 83002 (n=21)
Main Humber, Centreville Ck. 95 100 48 100/100 100 100 83104 (n=21) Main Humber, Rutherford Rd. 84 95 34 79/100 95 89 83020 (n=21) East Humber, Pine Grove 91 90 38 81/95 90 100 83004 (n=21)
Black Creek, Scarlett Road 95 38 38 24/90 100 100 83012 (n=21) Lower Humber, Old Mill 77 67 19 59/95 100 100 83019 (n=55)
Guideline 30 mg/L 1,5 250 0.03 mg/L 2 1.0 3/2.5 4 0.02 mg/L 2 6 mg/L 2 mg/L 6 mg/L Data Sources: Regional Watershed Monitoring Network. Guideline Sources: 1. CCME, 2006 2. Provincial Water Quality Objectives (MOE, 1999b); 3. CAST, 1992; 4. Rouse et al ., 1999; 5. Canadian Water Quality Guidelines (CCME, 2006); 6. Environment Canada & Health Canada, 2001
Humber_SW_Quality_FINAL_062408F.doc 11 Figure 2: Percent of Samples that Meet Guidelines for E.coli and Conventional Parameters Humber River State of the Watershed Report – Surface Water Quality
Total Suspended Solids
Median total suspended solids (TSS) concentrations in samples collected from 2002 - 2004 at all but the West Humber station at Highway 7 were below the guideline of 30 mg/L (CCME, 2006). The maximum observed at the West Humber station was 613 mg/L, which occurred during a storm event. Higher TSS concentrations would be expected during rain events as soil from pervious areas and accumulated grit and dirt from impervious surfaces are washed into streams. The majority of samples are taken during dry weather. TSS levels would be higher if sampling occurred during wet weather flow conditions. Short term exposures of high suspended sediment concentrations during rain storms or the spring freshet have been reported to severely affect in-stream biota (Waters, 1995).
Nutrients
Phosphorus is the limiting nutrient for plant growth in most inland waters and, as such, is often regarded as the principle cause of eutrophication in receiving waters. Median concentrations of phosphorus from 2002 to 2004 ranged from 0.03 mg/L near the outlet of the Cold Creek subwatershed (stn. 83009) to 0.08 mg/L on the West Humber below the Claireville dam (stn. 83002). The provincial guideline of 0.03 mg/L was exceeded between 29 and 100% of the time, with the greatest number of exceedances occurring at the Claireville station. Fine textured clay soils such as are found in the West Humber have been shown to contain more adsorbed phosphorus than coarse-sized sands and silts because of the larger surface-to-volume ratio of these soil particles (Sharpley et al. , 1992).
Nitrate (NO 3 - N) contributes to excessive plant growth at concentrations above approximately 1.0 mg/L (CAST, 1992). Nitrate has also been shown to produce chronic toxic effects in amphibian species at concentrations as low as 2.5 mg/L (Rouse et al ., 1999). Median nitrate concentrations exceeded 1 mg/L at only 1 of the 9 Humber River stations monitored. The 2.5 mg/L limit was exceeded relatively infrequently, mostly in the lower portions of the watershed and in the West Humber reaches.
Un-ionized ammonia is a form of nitrogen that is toxic to aquatic organisms at concentrations above 0.02 mg/L. Elevated concentrations are often associated with sewage treatment plants (STPs), of which there is only one discharging to the Humber River, at Kleinburg on the Main Humber. Illegal sewer connection discharges, failed septic systems, manure spreading, and cattle access to streams can also result in elevated ammonia concentrations. Most water samples collected met provincial standards for un-ionized ammonia (0.02 mg/L). The East at Pine Grove (stn. 83004) and Main Humber at Rutherford (stn. 83020) had slightly higher concentrations than other branches of the Humber River. The Rutherford Road station may be affected by the Kleinburg STP, as the plant is located a short distance upstream.
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Chloride
Road salts have come under increased scrutiny since they were deemed to be a toxic substance as defined in Section 64 of the Canadian Environmental Protection Act (Environment Canada and Health Canada, 2001). The five year risk assessment leading to the designation of road salts as ‘toxic’ suggested a limit for chloride (a major constituent of road salt) of approximately 250 mg/L for the protection of sensitive aquatic organisms. By contrast, the suggested irrigation water limit for agricultural crops ranges from 100 mg/L for sensitive plants to 700 mg/L for more tolerant ones (CCME, 2006). Chloride is highly soluble and does not readily adsorb to mineral surfaces. Hence, it is not effectively treated by stormwater technologies such as ponds that rely on settling for pollutant removal (SWAMP, 2003a). Chloride concentrations in the Humber River varied considerably among stations. The highest median values were recorded at the mouth of the Black Creek subwatershed (83012), which is fully urbanized. At this station, only 38% of samples collected were below the 250 mg/L limit. Further downstream, at the Old Mill station (83019), 67% of samples collected met the guideline and in all areas north of Steeles Avenue, over 90% of samples met the guideline.
Dissolved Oxygen
Measurements of dissolved oxygen are taken in the field at the time water quality samples are collected. Since samples are collected during the day-time, the measurements do not capture the daily lows, which typically occur during the evening. Only two sites registered occasional daytime guideline exceedances: the West Humber at the Claireville Dam and the Main Humber at Rutherford Road. The causes of reduced oxygen were not clear, but organic enrichment associated with Kleinburg sewage treatment plant discharges upstream of the Rutherford Road site may have contributed to periodically low levels at this station.
Wet Weather Data
The most recent wet weather sampling data available for conventional contaminants were from targeted wet weather sampling programs conducted by the OMOE and TRCA in 2003 and 2004. Additional West Humber data were available from a subwatershed study conducted in 1994 by Aquafor Beech Ltd. et al. (1997). All sampling programs employed grab sampling methods to collect samples, typically on the receding limb of the hydrograph, for a range of storm sizes.
Results from these programs for selected conventional pollutants are presented in Table 5. As expected, suspended sediment and nutrient concentrations were considerably higher than during dry weather (compare with Table 4). The higher values reflect pollutant contributions from storm and combined sewer discharges, runoff from farm fields and lawns, channel erosion and other sources unique to wet weather conditions. There were few chloride exceedances because the wet weather sampling program was conducted during the warm spring and summer months when road salt is no longer being applied to roads.
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Table 5: Wet Weather Concentrations During the Warm Season (1996 to 2004) % Meet Guideline TSS Chloride Total Nitrate Phosphorus Main Humber, Centreville 75 100 25 100/100 Creek (83104) Main Humber @ Rutherford 31 100 23 92/100 Road (83020) East Humber @ Pine Grove 62 100 25 75/100 (83004) East Humber, King Creek 75 100 8 82/91
West Humber @ Hwy 7 20 100 0 60/100 (83103) Guideline 30 mg/L 250 mg/L 0.03 mg/L 1.0/2.5 mg/L Sources: MOE Lake Ontario Priority Pollutant Monitoring Program (2003-2004); TRCA Regional Watershed Monitoring Network (2002-2004); Aquafor Beech Ltd. et al., 1997. N = 8 at the Centreville Creek station and 12 to 13 at the other four stations.
The risk posed by poor water quality to the health of aquatic communities is a function of, among other factors, the type and concentration of chemicals, the frequency and duration of exposure, and the type and diversity of aquatic organisms present in the receiving waters. Unfortunately, provincial and federal water quality guidelines are represented by a single threshold value, not multiple or scaled values associated with varying exposure durations and habitat types. Thus, while the results provided here indicate that water quality guideline exceedances are greatest during wet weather, it should be recognized that, all other factors remaining equal, the consequence of guideline exceedances on the health of aquatic communities during short duration wet weather events may not be as severe as during longer duration dry weather periods.
Rating for the Conventional Pollutant Indicator
The measures and targets selected for meeting the surface water quality objective of managing the Humber River watershed with respect to conventional contaminants are provided below, along with a rating for existing conditions in the watershed. Targets are provided for 2005 and 2015 based on assessments completed for the previous Humber River Watershed report card (TRCA, 2000).
As shown in Table 4, the 2015 target of meeting 70% of guideline levels at all 905 stations is close to being met for all conventional variables except total phosphorus. Total phosphorus levels declined significantly in the 1970s and early 1980s due to decommissioning of smaller sewage treatment plants discharging to the Humber River, legislation which limited the use of phosphorus in detergents; and programs promoting the control of phosphorus discharges to watercourses (TRCA, 1996). Nevertheless, current phosphorus concentrations remain above the relatively stringent guideline for this nutrient. The West Humber also had exceedances beyond the 70% level for TSS, and chloride levels in Black Creek did not even meet the 50%
Humber_SW_Quality_FINAL_062408F.doc 15 Humber River State of the Watershed Report – Surface Water Quality target. There were no significant increases in conventional contaminants since the 1990 to 1996 period, with the exception of chloride, which is increasing as the road network becomes increasingly dense.
Objective: Protect and restore surface water Overall Rating quality with respect to toxic contaminants and other pollutants such as sediment, nutrients, bacteria and road salt Good Indicator Measure Target Conventional Concentrations of conventional 2005: In the upper reaches of the pollutants pollutants (suspended solids, watershed where development is phosphorus, nitrate, ammonia, taking place, levels of conventional dissolved oxygen and chloride) pollutants have not increased beyond 1990-1995 levels.
2012: Levels of conventional pollutants in the Main, East and West Humber meet guidelines for at least 85% of samples. In the Lower Humber and Black Creek, levels of conventionals meet guideline criteria for at least 75% of samples.
Sediment load Target to be determined
A rating of good was assigned to the conventional contaminants indicator based on 2005 targets and progress towards 2012 targets for this indicator. Among subwatersheds, the poorest ratings were achieved on the West Humber, Black Creek and the Lower Humber.
4.3 Organic and Metal Contaminants: the Chronic Effects Indicator
Organic Compounds
Organic contaminants such as pesticides, poly-chlorinated biphenols (PCBs) and polycyclic aromatic hydrocarbons (PAHs) have been linked to chronic health effects in aquatic organisms, terrestrial wildlife species and humans. Aquatic impacts of organic pollutants can include physical deformities, tumours and lesions, some leading to population declines through increased embryo mortality and damage to reproductive systems. Many of these compounds have been demonstrated, or are believed to be carcinogenic to humans.
Forty-one harmful pollutants were identified under the Canada-Ontario Agreement (COA) for priority management in the Great Lakes Basin ecosystem. The first group of these, called ‘Tier 1' contaminants, consist of 14 contaminants known to persist and biomagnify in the
Humber_SW_Quality_FINAL_062408F.doc 16 Humber River State of the Watershed Report – Surface Water Quality environment, and have been targeted for virtual elimination. Significant progress has been made over the past 15 years in reducing production and release of these chemicals, and some, such as dichloro-diphenyl-trichlorethane (DDT), Chlordane, Mirex, Alkyl-lead and Toxaphene are no longer being produced in Ontario.
The second group, called Tier II contaminants, is believed to be persistent and have the potential for biomagnification and toxicity. In some cases, these chemicals have already caused local adverse impacts within the Great Lakes basin, but there is not sufficient agreement among scientists in both the U.S. and Canada to warrant setting joint targets and goals with regard to these substances. The pollutants in the Tier II category include 17 PAHs and various other organic compounds.
Sampling for organic compounds on the Humber River at the Old Mill station was conducted in 1991/92, 2000/01 and most recently in 2003/04 as part of the Ontario Ministry of the Environment’s Lake Ontario Priority Pollutants Monitoring Program. Table 6 summarizes program results for Tier 1 contaminants. Unfortunately, results of the sampling programs are not directly comparable because of differences in sampling and laboratory analytical protocols. The 1991/92 program samples were collected over a 24 hour period and targeted high flow events during the spring freshet. The 2000-2001 concentrations represent a single 28 day composite of samples collected at 6 hour time intervals. These samples are a mix of dry and wet weather. The 2003/04 samples were collected at a single point on the rise, peak or run of stormflow hydrographs, and during dry weather.
Only PCBs were observed at levels exceeding provincial guidelines in the 2003/04 program. Other organic compounds with exceedances in earlier years include Aldrin/Dieldrin, B(a)P, Mirex and DDT. It is not clear whether or not the year-to-year differences are a result of declining levels or differences in sampling methods and laboratory analytical protocols. It is also unclear where these contaminants are coming from since they are subject to atmospheric transport and deposition, and are persistent, hence they can reside for long periods of time in stream sediments and animal tissues.
Among Tier II contaminants, only PAHs and cadmium (discussed in the next section) were analyzed in the 1991/92 and 2000/01 studies. Unlike other organic compounds, PAHs are not manufactured directly by humans, but enter the environment indirectly as by-products of combustion processes. Residential heating, vehicular exhaust, power generation and wood burning are all sources of PAHs. Emissions from these sources are deposited on surfaces and wash off with stormwater runoff into rivers and creeks, where they accumulate in sediments and aquatic organisms (Sharma et al ., 1997).
PAH levels are a concern because these compounds are a known carcinogen and can have detrimental effects on the health of aquatic organisms. Humans are usually more at risk from inhalation of air-borne PAHs than through consumption of fish or other freshwater foods because our lifetime exposure to sources such as vehicular exhaust and wood smoke can be significant.
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Table 6: Levels of Canada-Ontario Agreement ‘Tier 1' Contaminants in the Lower Humber River at Old Mill station 1991/1992 survey 2000/2001 survey
% > MDL % meet PWQO % > MDL % meet COA PWQO PWQO
Tier 1 (ng/L) Contaminants MDL* dry wet dry wet MDL dry/wet dry/wet (ng/L) (n=22) (n=25) (n=22) (n=25) (ng/L) comp. comp. (n=12) (n=12)
chlordane 60 0.02 86 76 100 100 0.2 0 100 DDT 3 0.05 32 64 100 100 ------PCBs 1 1.0 37 44 68 56 1.0 75 75 Aldrin/ 1.0 0.01 82 76 100 8 ------Dieldrin HCB 6.5 0.01 32 44 ------mirex 1 0.05 0 0 100 100 0.5 0 100 B(a)p 15** 0.2 50 91 ------2.0 83 67 Mercury 200 20 9 100 100 20 8 100 Source: Ministry of the Environment. Other Tier 1 contaminants were not selected for analysis because they are not usually detected in Toronto area surface waters. *MDL = Laboratory Method Detection Limit **Canadian Water Quality Guideline
At the Old Mill station in the Humber River, concentrations of several PAHs occasionally exceeded provincial guidelines (Table 7). Comparing the two survey years, some PAHs appear to have declined. Like other organic compounds, however, this apparent trend may simply be a result of differences in sampling methods and laboratory analytical procedures. Given the increase in traffic and use of fuel in the watershed for residential heating and commercial uses, there is no reason to expect that PAH concentrations would be declining.
Pesticides currently “in-use” were sampled in 1998 and 1999 in the Don and Humber Rivers (Struger et al ., 2002). In this study, 159 pesticides were analyzed in 133 samples collected during wet and dry weather, including common pesticides used in urban lawn care and agriculture such as diazinon, 2,4-D, MCPP and dicamba. Only 10 of the 159 pesticides sampled were detected, of which the most frequently detected chemicals were MCCP (30% of samples collected), diazinon (29%), 2-4-D (7%) and atrazine (4%). All of the pesticides detected were below available water quality guidelines, except diazinon and carbofuran, which exceeded their respective PWQOs in 20 and 1% of samples collected, respectively.
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Table 7: Levels of Poly-Aromatic Hydrocarbons (PAHs) Sampled in the Lower Humber River at the Old Mill Station 1991/1992 survey 2000/2001 survey % > % > MDL % > PWQO % > MDL PWQO
PAHs PWQO MDL dry wet dry wet MDL dry/wet dry/wet (ng/L) (n=22) (n=25) (n=22) (n=25) (ng/L) comp. comp. (n=12) (n=12) Phenanthrene 30 0.2 85 91 95 64 1 100 75 Anthracene 0.8 --- 46 95 55 1 0 100** Fluoranthene 0.8 0.2 100 96 0 5 1 100 100 Pyrene 25* 0.2 100 96 ------1 100 58 Benzo (a) 0.4 0.2 47 9 2 83 17** anthracene 50 91 Chrysene 0.1 0.2 80 96 16 5 2 92 8** Benzo (b) ------0.2 84 96 --- 2 83 --- fluoranthene Benzo (k) 0.2 ------2 92 8** fluoranthene Benzo (e) ------2 92 --- pyrene Benzo (a) 15** 0.2 50 91 0 86 2 83 67 pyrene Perylene 0.07 0.2 --- 41 95 59 2 33 67** Indeno (1,2,3- c,d) --- 0.5 50 86 ------2 92 --- pyrene Dibenzo (a,h) 2.0 0.5 --- 27 95 73 2 25 75 anthracene Benzo (g,h,i) 0.02 0.5 45 82 74 18 2 92 8** perylene Source: Ministry of the Environment, (Boyd et al , 1999) *Canadian Water Quality Guideline *** The percent of samples meeting the PWQO is set equal to 100 minus %>MDL for variables with method detection limits greater than the PWQO. In these cases, the percent of samples meeting the PWQO may be less than stated.
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Trace Metals
Metals are found naturally in the environment, but many are toxic to aquatic life at elevated levels. Copper, lead and zinc originate from urban and industrial land use activities and as such are the most common heavy metals in stormwater runoff (Marselek and Shroeter, 1988). Mercury and cadmium are designated under the Canada-Ontario agreement (COA) as Tier1 and Tier 2 contaminants, respectively. Mercury comes from natural sources, such as decaying vegetation and degassing of soils, as well as anthropogenic sources, such as base metal recovery, coal combustion, paint application, and the chlor-alkali industry. The major anthropogenic sources of cadmium are corrosion of galvanized pipes, discharge from metal refineries and runoff from waste batteries and paints. Natural sources from weathering of rocks can contribute significant quantities of this element to streams.
Table 8 shows the percentage of samples that meet guidelines for selected metals at nine stations on the Humber River. Results are presented graphically in Figure 3. Guideline levels were exceeded most frequently for iron, while lead, copper, zinc, and cadmium exceeded guidelines in fewer locations and less frequently. Other metals, such as mercury, were not included in the table because sample concentrations were consistently lower than the Provincial Water Quality Objective. The Lower Humber, Black Creek and West Humber stations exhibited the highest metal concentrations overall. Cadmium, lead and iron were found throughout the watershed, even in predominantly rural catchments, suggesting that natural weathering of rocks, soil characteristics and atmospheric deposition may be significant sources of these contaminants. Lead concentrations in stormwater have declined dramatically over the past two decades due primarily to the phase out and ultimate elimination of lead as an anti- knock additive in gasoline.
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Table 8: Percent of Samples that Met Guidelines for Selected Trace Metals at Humber River Monitoring Stations (04/02 - 02/04) Percent Meet Guideline Lead Copper Zinc Cadmium Chromium Iron Nickel Main Humber, Cold Creek 86 100 100 76 100 39 100 83009 (n=23) Main Humber, Albion Hills 93 100 100 86 100 86 100 83018 (n=28) West Humber @ Hwy 7 74 87 97 83 100 17 100 83103 (n=23) West Humber @ Claireville 94 94 76 100 100 47 100 83002 (n=17) Main Humber, Centreville Ck. 88 100 100 92 100 88 100 83104 (n=25) Main Humber @ Rutherford Rd. 100 93 80 100 93 60 93 83020 (n=15) East Humber @ Pine Grove 100 100 94 100 100 81 100 83004 (n=16) Black Creek @ Scarlett Road 94 81 63 100 94 50 94 83012 (n=16) Lower Humber @ Old Mill 85 78 89 85 100 56 100 83019 (n=55) Guideline 5 ug/L 5 ug/L 20 ug/L 0.5 ug/L 8.9 ug/L 300 25 ug/L ug/L Data Source: Regional Watershed Monitoring Network
Humber_SW_Quality_FINAL_062408F.doc 21 Figure 3: Percent of Samples that Meet Guidelines for Selected Trace Metals Humber River State of the Watershed Report – Surface Water Quality
Contaminants in Fish Tissues
Tissue analysis of juvenile (i.e., young-of-the-year) fish and sport fish can be used to demonstrate the degree of threat presented by pollutants to aquatic species and also to humans through fish consumption. The detection of organic contaminants or metals in fish flesh is an indication that these pollutants are present in river water or sediments in forms that are biologically available, and depending on the nature of the contaminant, may be bio- accumulated through the food chain. Restrictions on the consumption of sport fish are set if these contaminants exceed established levels in order to protect humans against potential adverse health effects. Table 9 summarizes available information regarding mercury, PCB and DDT contaminant levels in tissue samples from young-of-the-year fish caught in Humber River tributaries (Petro, 2005).
Table 9: Young-of-the-Year Fish Sampling Locations Where Fish Tissue Guideline Exeedances Occurred. Location Mercury PCB DDT (<0.033 ug/g) (<100 ng/g) (<14 ng/g)
East Humber @ yes no no Riverside Dr.
Black Creek @ Scarlett no yes no Road
Lower Humber @ Finch yes no no Ave.
Lower Humber @ no yes no Old Mill
West Humber, no yes yes Below Clairville Dam
Rating Fair Fail Excellent Source: (Petro, 2005)
Tissue analysis of sport fish sampled in the Humber River in 2004 showed restrictions on some species of fish tested at 5 of the 7 stations (Table 10). Fish were safe to consume up to a maximum limit of 8 meals per month (4 for children under 15 and women of child bearing age) at Grenadier Pond in High Park and on the Humber River north of Bolton. Comparison of 1999 and 2004 restriction levels showed no change over the 5 year period at all but the West Humber station below Claireville Dam, where there was a minor improvement for one species. Three fish species that spawn in the Humber River - chinook salmon, rainbow trout, and brown trout - had consumption restrictions. Since these spawning fish spend most of their lives in Lake Ontario, consumption restrictions on these fish are not indicative of poor water quality in the Humber River.
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Table 10: Sportfish Consumption Advisory Limits 1 for Sites in the Humber Watershed Location Substances Species Restricted Fish Length Restriction level Tested (cm) (# of meals per month) 2 1999 2003 1999 2003 West Humber Mercury, Largemouth 35-55 35-55 4 4 River (Claireville PCBs, Mirex, Bass 25-30 25-30 4 4 Reservoir) Pesticides Brown Bullhead 20-25 20-25 4 4 Rock Bass 3 — — safe safe Carp --- — safe safe White Sucker ------safe safe Yellow Perch West Humber Mercury,PCBs, Carp 35-45, 45-55 35-45,45-55 4, 2 4, 4 River (below Mirex, Largemouth --- — safe safe Claireville Dam) Pesticides Bass Lake Wilcox Mercury, Largemouth 35-45,45-55 35-45,45-55 4, 2 4, 2 PCBs, Mirex, Bass n/a 55-65 n/a 4 pesticides Carp ------safe safe Brown Bullhead ------safe safe Bluegill ------safe safe Black Crappie ------safe safe Yellow Perch ------safe safe Rock Bass Humber River Mercury, Brown Trout 45-65, >65 n/a 2, 1 n/a (Queensway PCBs, Mirex, Northern Pike n/a >75 n/a 4 Marsh)4 Pesticides, Largemouth n/a 35-45 n/a 4 Dioxins and Bass n/a 20-25,25-30 n/a 4,2 Furans Rock Bass n/a 35-45 n/a 4 Brown Bullhead n/a 45-65,>65 n/a 4,2 Carp n/a --- n/a safe White Sucker Humber River Mercury, Chinook Salmon n/a 55-75, >75 n/a 2, 1 ( Old Mill Area - PCBs, Mirex, Rainbow Trout n/a 45-55, >55 n/a 4, 2 spawning runs) Pesticides, Brown Trout n/a 35-55,55-65, n/a 4, 2, Dioxins and 65-75 n/a 1 Furans
Ref.: Ministry of the Environment, 2000, 2004 1. This table presents data only for those sites with consumption advisories that are stricter than the minimum level of eight meals per month. Sampling sites for which their were no restrictions below the 8 meal maximum include the Humber River North of Bolton (2 fish species tested) and Grenadier Pond in High Park (8 fish species tested). 2. Restriction level refers to the maximum number of monthly meals it is safe to consume. Eight meals per month are permitted in ‘safe’ areas (4 for children under 15 and women of child bearing age). (MOE, 2003). 3. Tested for Mercury only
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Rating for the Organic and Metal Contaminants Indicator
The indicator, measures and targets selected for meeting the surface water quality objective of managing the Humber River watershed with respect to metals and organic contaminants are provided below, along with a rating for existing conditions in the watershed. These targets are generally consistent with the Toronto Remedial Action Plan and Toronto Wet Weather Flow Management Master Plan objectives for toxic contaminants. Although included as a target in the 2000 Humber River report card, it was not possible to assess with confidence whether ‘priority toxics’ were detected in 25% less samples than in the 1991/92 survey because of changes in sampling method and laboratory procedures. Hence, this target was excluded.
Objective: Protect and restore surface water Overall Rating quality with respect to toxic contaminants and other pollutants, such as sediment, nutrients, bacteria and road salt Fair Indicator Measure Target Heavy metals Concentrations of persistent Concentrations of metals and organic and organic organic contaminants, pesticides compounds meet PWQOs. contaminants and heavy metals in surface waters, and in fish (young-of-the Organic contaminant levels in young- year and adult sport fish) of-the year fish meet IJC and CCME guidelines.
Restrictions on sport fish consumption have not increased from 1999 levels.
An overall rating of fair was assigned to the chronic effects indicator. This rating reflects excellent water quality for ‘Tier 1' organic compounds, a failing grade for PAH and metal concentrations in water, a fair grade for tissue contaminants in young of the year fish and a passing grade for sport fish (no change in consumption restrictions since 1999).
4.4 Water Quality Trends in the Humber River Watershed
Trends in water quality were assessed for copper, zinc, TSS, chloride and phosphorus at the Old Mill Station on the Lower Humber (Figure 4). This station was selected for trend analysis because it has a large and consistent set of data collected and analyzed by the same agency (OMOE) over the entire period of record. Also, the station is located below the confluence of all major tributaries and therefore provides a good overall view of water quality trends in the watershed. Other variables, such as nitrate and lead, were not included in the analysis because of changes in analytical methods midway through the historical record.
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Figure 4: Trends in Annual Median Concentrations of Chloride, TP, TSS, Copper and Zinc at Old Mill Station (Lower Humber)
Chloride Total Phosphorus
200 0.16 180 0.14 160 0.12 140 0.1 120 100 0.08
80 0.06 60 0.04 40 0.02
20 Median Concentration (mg/L) Median Concentration(mg/L) 0 0 1988 1990 1992 1994 1996 1998 2000 2002 2004 1980 1983 1986 1989 1992 1995 1998 2001 2004
Total Suspended Solids Copper
70 14
60 12
50 10
40 8
30 6
20 4
10 2 MedianConcentration (ug/L) MedianConcentration (mg/L)
0 0 1980 1983 1986 1989 1992 1995 1998 2001 2004 1979 1982 1985 1988 1991 1994 1997 2000 2003
Zinc
14
12
10
8
6
4
2 Median Concentration(ug/L)
0 1988 1990 1992 1994 1996 1998 2000 2002 2004
Note: trend results for trace metals may be influenced by periodic changes in laboratory analytical procedures over the historical record.
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Chloride was the only one of the five variables analyzed that showed an upward trend (Figure 4). The increase is associated with the rising number and density of roads to which road salts are applied. Unfortunately, the many stormwater ponds and wetlands in newer 905 area developments have little effect on dissolved substances such as chloride because they remove pollutants primarily by sedimentation. It is too early to judge whether salt management plans in Toronto, Peel and York will help ensure chloride levels do not increase further.
A significant decline in phosphorus levels occurred in the 1970s and early 80s in several Ontario watersheds due to restrictions on phosphates in detergents, tighter industrial and wastewater discharge controls and more efficient use of fertilizers on crops. The decline in phosphorus from 1980 to 1986 shown in Figure 4 may in part reflect the tail end of this province-wide trend.
A similar decline in TSS around the same time, however, appears to have also exerted some influence on phosphorus levels (Figure 4). Approximately 80% of phosphorus in streams is associated with solid particles. The same is true for trace metals such as zinc and copper. When TSS levels are elevated, so too are the contaminants that bind readily to it. Regression analysis showed that 70% of the variation in median phosphorus concentrations, is explained by variations in TSS. The same analysis for zinc and copper showed that 49 and 51% of concentration variations in these constituents were explained by changes in TSS. Further investigations would be required to determine the cause of the decline in TSS during the early 1980s. Since then, phosphorus, TSS and copper concentrations have leveled off. A similar downward trend for zinc is not evident because data were only available from 1988 onwards, after the decline in TSS had occurred. Changes in analytic methods over the historical period also complicate the analysis, especially for metals, which are present at extremely low levels in surface waters.
These data suggest that stormwater management controls in newly developed areas appear to be effective in removing contaminants associated with suspended sediment, such as copper, and phosphorus. If they were not, a significant deterioration in Humber River water quality would have been expected as the urban footprint in the watershed has grown considerably since the early 1980s. Of course, receiving water quality is not improving either, and these data do not reflect wet weather conditions, when the greatest impacts would be expected. Nevertheless, the evidence that dry weather levels of key water quality variables are not increasing can be counted as a success, considering the substantial development pressures mitigating against this result.
4.5 Other Issues: Spills, Landfills, Sanitary Servicing, Golf Courses
Spills
The effect of spills on aquatic life or water quality has not been well documented. Many of the substances spilled into the environment accumulate in stream sediments, which reduce the quality of habitat for benthic invertebrates and other bottom feeding organisms. Oil clings to vegetation and grasses on the banks of rivers, posing a threat to animals that feed on these plants.
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In freshwater systems, petroleum contamination adversely affects all trophic levels of the food web, causing disruption to the complex and dynamic equilibrium of the aquatic ecosystem (Li and McAteer, 2000).
The toxicity of a spill will depend on the spill duration, the type of spill, the amount, rate and time of release, the sensitivity of the receptor and other spill characteristics. Compounds with rapid bio-concentration kinetics, such as naphthalene, phenanthrene and benzene, are more likely to be acutely toxic (Davis et al ., 1984).
Studies summarizing spills data were conducted for three municipalities in the Humber River watershed: the City of Vaughan, the City of Toronto and the Town of Richmond Hill (Li, 2002a, 2002b, 2002c), as well as for the 905 area more generally (Li, 2002d). These studies reported that between 1988 and 2000, there were approximately 900 oil spills and 750 chemical spills in the Humber River watershed, of which roughly half drained to the Humber River or one of its tributaries. The majority of oil spills occurred on major roads and parking lots, whereas chemical spills were mostly associated with commercial plants, storage facilities, pipelines, hydro facilities and tanker trucks. In terms of volume, the chemical, transportation and general manufacturing sectors contributed the most to chemical spills, often as a result of container or fuel tank leaks.
Landfills
There are 29 abandoned or closed landfill sites in the Humber River watershed. These are located in the following subwatersheds: 10 in the Lower Humber, 8 in the Main Humber, 6 in the East Humber, 2 in the West Humber and 3 in Black Creek (OMOE, 1991). All these landfills were active prior to the establishment of Ministry of the Environment regulations on the design of landfills to protect surface and groundwater resources. Hence, liners or leachate collection systems were probably not installed. Data on leachate discharge from these landfills were not available at the time this report was prepared.
Sanitary Servicing
Currently, there is one sewage treatment plant discharging to the Main Humber River in Kleinburg. A new modern sewage treatment plant will likely be constructed in Nobleton over the next few years. Historically there were several plants operating in the City of Toronto, but all of these plants discharging to the Humber River have been decommissioned.
Many rural area residents in the watershed rely on septic systems to meet their wastewater disposal needs. On the Humber River, a tracer study of septic system effluents in a rural community showed that septic system contributions to stream flow were a negligible fraction of total flow in the river, indicating that pollutant loading from these sources was not a significant concern (Gartner Lee, 2002). A similar result was reported in a modelling study of bacteria transport in Centreville Creek and the East Humber during wet weather, but during dry weather, wildlife and septic system failures were predicted to be the primary sources of bacteria delivered to the swimming area at Albion Hills Conservation Area. Livestock access was suggested as the predominant dry weather bacterial source in the East Humber (TRCA, 1991).
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Golf Courses
There are 24 golf courses in the Humber River watershed, covering 1300 hectares of land. This land use activity can be a source of pesticides and nutrients if appropriate best management practices are not applied. There are few local data assessing nutrient and pesticide contributions to rivers or streams from golf courses. Humber River data from a recent monitoring study of in-use pesticides and nutrients in the Toronto area rivers suggested that the Scarlett Woods Golf Course was probably not a significant source of nutrients or pesticides to the river (Struger et al ., 2002).
Water use can be a serious concern if the golf course is relying on the river as its source of irrigation water. Golf course turf requires significant water inputs that are often drawn out of the adjacent watercourse which can have significant impacts on stream health. Loss of vegetation, creation of ponds, and pesticide and fertilizer use may also be significant depending on golf course design. Aware of the growing public concern over water and chemical use, many golf course managers have taken proactive measures to retrofit courses to meet industry environmental standards (Webb, 2002).
5.0 SUMMARY AND MANAGEMENT CONSIDERATIONS
The diverse geology and land cover in the Humber watershed is reflected in the quality of its surface waters. The lower reaches of streams in the West Humber with its clay soils, low baseflow rates and urbanizing landscape exhibit the poorest overall water quality. Conditions at the mouth of Black Creek and the Old Mill station on the lower Humber are not much better. The absence of modern stormwater management practices in the older urban developments upstream of these stations contributes significantly to the dirty water at these sites. By comparison, surface waters in the upper portions of the watershed on Cold Creek, Centreville Creek and on the upper Main Humber display reasonably good water quality. Even the East Humber, which has experienced moderate levels of urbanization over the past 10 years, remains relatively clean.
The concentration of suspended solids in surface waters is a particularly important water quality indicator because solid particles act as a primary transport vector for other contaminants such as phosphorus, most heavy metals and bacteria. Levels of suspended solids were highest in the West Humber, where erodible clay soils predominate, followed by the Lower Humber at Old Mill. Control of sediment must be targeted at high flows as the majority of sediment is generated and transported during storm events. Several options are available. These may include riparian buffers and restrictions on cattle access in rural areas, improved sediment controls on construction sites in urbanizing areas, and enhanced management of stormwater in cities and towns. The key is to reduce the volume of storm water that runs off into streams by infiltrating as much of it as possible.
Bacteria levels in the rivers often failed to meet the provincial guideline for recreational swimming, even on streams dominated by natural and rural land uses. For instance, only 29% of samples collected in the mostly rural Centreville Creek subwatershed met the guideline, although mean concentrations were relatively low. The highest concentrations were observed in Toronto and on the West Humber in the 905 area. These areas should be the focus of remedial actions targeted at reduced posting frequencies at Humber waterfront beaches. A
Humber_SW_Quality_FINAL_062408F.doc 29 Humber River State of the Watershed Report – Surface Water Quality study conducted by the National Water Research Institute will offer direction on which actions will best achieve this end. Using DNA fingerprinting technologies, this study identifies the relative importance of fecal matter from various sources - humans, pets, geese, livestock and other mammals - to bacteria levels observed along the Lake Ontario waterfront near the mouth of the Humber River.
The somewhat stringent provincial objective for phosphorus in receiving waters was rarely met anywhere in the Humber watershed. Elevated levels in part reflect the limited ability of current stormwater ponds and other end-of-pipe stormwater management facilities to remove this constituent. Even during dry weather, effluent concentrations from stormwater ponds and wetlands are typically at least double the PWQO for phosphorus. Stormwater infiltration practices such as permeable pavement and underground perforated pipe systems are much more effective in reducing phosphorus loads but to date, there are very few instances in the Humber watershed where these types of practices have been implemented.
Chloride is a major constituent of de-icing salts applied to roads during the winter. Chloride levels are rising due to increasing urbanization. Chloride concentrations during winter in the Lower Humber, West Humber and Black Creek are often above the threshold established to protect aquatic life. A leveling off of chloride concentrations in Humber streams may be expected in the future as municipal salt management plans, developed in 2004, begin to take effect. Alternatives to road salts will need to be considered on local roads if significant reductions in chloride levels are to occur.
The sources of organic compounds are almost as diverse as the compounds themselves. Many enter the watershed through atmospheric deposition, others are sprayed on vegetation to control weeds or insects, some enter through storm or sanitary sewers, as discharge from industry or as accidental spills, and some of these same chemicals are so persistent that even decades after being phased out, they continue to be detected in stream sediments and fish. Federal governments in Canada and the United States work together to reduce the use of organic compounds that have been shown to persist and bio-accumulate in the food chain. These activities may take the form of outright bans on chemicals or involve targets for reduced chemical use through, for instance, industrial pollution prevention programs. The slow decline in levels of some banned chemicals (e.g. PCBs) in the Great Lakes has demonstrated the effectiveness of these measures.
In order to more accurately identify sources of pollutants of concern and to evaluate the effectiveness of management actions, special water quality monitoring studies involving wet weather surface water quality sampling should be undertaken. Particular attention should be given to bacteria levels during wet weather flow conditions in Black Creek, West Humber and Lower Humber tributaries to identify significant sources.
Organic and inorganic chemicals entering watercourses through spills or accidental discharges are controlled by federal, provincial and municipal governments through a complex array of regulations and programs. The large number of spills that continue to occur in the Greater Toronto Area suggest that still more could be done in this area. Actions that would help to address this problem include better spill prevention programs, improved structural controls on spill prone areas, stronger penalties for violations and stepped-up enforcement of existing laws
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Pollutants deposited into waterways via the atmosphere are not so easily managed on an individual watershed basis since they often originate many kilometers from where they are deposited, even from entirely different continents. Some, such as polycyclic aromatic hydrocarbons (PAHs), are classified as probable human carcinogens. Reductions in fossil fuel consumption and use of cleaner energy sources such as wind power and solar energy would help to cleanse the air of these contaminants. Pesticide by-laws, such as was enacted in Toronto in 2004, will also help to reduce atmospheric emissions of some volatile compounds. Clearly, significant reductions in atmospheric pollutants will require fundamental changes in our lifestyles.
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6.0 REFERENCES
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