Indicators of Watershed Health
The Watershed Report Card evaluates local watershed conditions using a standardized set of indicators. The indicators include: surface water quality, forest conditions, groundwater quality and wetland cover. A set of grades are applied to each indicator, ranging from A (excellent) to F (very poor), and reflect the conditions over a five year period (most recently 2007-2011). Let’s take a look at each indicator.
Surface water is the water that flows through streams, rivers and lakes and is a source of both private and municipal drinking water supplies.Conservation Authorities typically assess surface water quality by analyzing water quality indicators such as water chemistry and the aquatic organisms that live in the bottom all water bodies. The Ontario Ministry of the Environment points out that:
“Monitoring stream-water quality can help us understand the impacts of land-use activities on water quality, enabling us to make informed decisions about managing and protecting our water resources”.
In the 2011 Guide to Developing Conservation Authority Watershed Report Cards, Conservation Ontario recommended the use of the following three indicators to assess surface water quality at the watershed and subwatershed scales:
• Total Phosphorous (nutrients);
• E. coli (Escherichia coli) (bacteria); and,
• Benthic Macroinvertebrates (aquatic health).
These indicators reflect key issues related to surface water quality across the province and are described below.
Total Phosphorous is a nutrient that occurs both naturally and as a result of human activities. It is typically used in fertilizers and is found in municipal waste and from other human sources. It promotes plant growth which is good for agricultural yields, yet high concentrations can be harmful to the environment causing algae blooms which can reduce the oxygen available to plants and fish.
Wetlands and forests help to filter and absorb phosphorus, reducing its impact on lakes and rivers. Healthy vegetated riparian zones reduce the amount of phosphorus entering surface water and groundwater.
The Provincial Water Quality Monitoring Network (PWQMN) is the main source of total phosphorous data for many Conservation Authorities. Other Conservation Authority or partner agency monitoring programs may provide data for some watersheds.
Benthic Macroinvertebrates are small, aquatic organisms that live in the bottom of rivers, lakes and wetlands. Some species are more tolerant of poor water quality than others and as such, benthic macroinvertebrates are a good indicator of long term water quality conditions. Most Conservation Authorities participate in the Ontario Benthos Biomonitoring Network (OBBN) in partnership with the Ontario Ministry of the Environment to collect and analyze benthic macroinvertebrate data. Otonabee Conservation is a partner in the OBBN and collects benthic macrovertebrate samples annually during the spring and fall seasons.
E. coli (Escherichia coli) is a bacteria that is widely accepted as the key indicator of fecal contamination in surface waters. The main sources of E. coli are municipal sewage discharges, runoff from failing septic systems and agricultural operations.
E. coli levels in surface water are often elevated after precipitation events or snow melts. The presence of E. coli in drinking water sources may impact human health by causing severe illness including diarrhea, cramps and fever.
Currently, there is no province-wide program whereby Conservation Authorities collect water samples for E. coli. While Otonabee Conservation does not regularly sample for E. coli, the Peterborough County-City Health Unit (PCCHU) maintains a routine surveillance program for public beaches during summer months to ensure that the water quality is safe for swimming. E. coli data is not included in the assessment of surface water quality in the 2013 Otonabee Region Watershed Report Card.
Stormwater Poses Significant Threat to Surface Water Quality
Heavy rainfall or snowmelt can cause pollutants from activities on the land, such as parking lots, construction and lawn maintenance, to travel quickly as runoff into receiving watercourses. Under natural conditions, stormwater is filtered and taken up by trees and other plants and absorbed into the ground. In urban areas, however, water rapidly flows overland into storm drains, municipal sewers and drainage ditches that outlet to streams, rivers and lakes. This runoff can transfer contaminants such as pesticides, heavy metals, oils and bacteria, along the way. Potential impacts of stormwater runoff include:
- increased flood risk,
- shoreline and streambank erosion,
- ‘murky’ surface water caused by increased sediment,
- altered stream flows,
- damage to municipal infrastructure, and
- surface water contamination.
Conservation Authorities promote smart environmental practices such as low impact development and environmentally friendly activities to manage or prevent the impacts of stormwater runoff.
Forests provide habitat and shade, help to clean our air and water, stabilize soils and promote water infiltration that reduces both erosion and flooding. Forests also help to cool the land and air. GIS mapping resources are a common tool used by Conservation Authorities to assess forests. Most Conservation Authorities use the Southern Ontario Land Resources Information System (SOLRIS) as their primary source of forest data.
In the 2011 Guide to Developing Conservation Authority Watershed Report Cards, Conservation Ontario recommended the use of the following three indicators to assess forest conditions at the watershed and subwatershed scales:
- % Forest Cover
- %Forest Interior, and
- % Forest Riparian Zone.
These indicators reflect key issues related to forests across the province and are described below.
Forest Cover is an area with more than 60% tree cover and where the trees are greater than 2 m in height.
Forest Interior is the forested area that is more than 100 m from the forest edge. The outer 100 m of a forested area is considered ‘edge’ habitat and prone to high predation, sun and wind damage, and is more susceptible to invasive species than the forest interior. Certain wildlife species such as Ovenbirds, Bobcats and Grey wolves require interior forests for their survival.
Forested Riparian Zone is a 30 m wide strip of forested land along stream banks or shoreline. These vegetated zones provide important habitat for birds, fish and other wildlife and help improve water quality by naturally filtering sediment and contaminants before they enter surface water. In addition, forested riparian zones help to reduce or prevent flooding and erosion.
All three indicators described above were used to assess forest conditions as reflected in the 2013 Otonabee Region Watershed Report Card.
Conserving and Protecting Our Forests
“Over the past two decades, there has been great change in the management of natural resources in Ontario and around the world. As has occurred in many locations, Ontario’s forest policy has shifted to a more balanced ecological approach. This means the forest is viewed as part of a larger ecosystem which is actively managed to protect and conserve a whole range of values and uses.” – Ontario Ministry of Natural Resources
Groundwater is found in the cracks and spaces in soils, sand and rock, moves very slowly and once contaminated, is difficult or impossible to restore. Conservation Authorities typically monitor groundwater chemistry (i.e. nutrients, metals, chloride & nitrates). The Provincial Groundwater Monitoring Network (PGMN) is the main source of water chemistry for many Conservation Authorities.
In the 2011 Guide to Developing Conservation Authority Watershed Report Cards, Conservation Ontario recommended the use of the following three indicators to assess groundwater:
- Nitrite and Nitrate; and,
Nitrite + Nitrate are forms of nitrogen found in water. Although nitrogen occurs naturally in rocks and groundwater, the concentration of nitrogen can be significantly increased by the overuse of fertilizer, manure applied as a nutrient, and leaky septic systems.
Chloride is a naturally occurring element that can be found in concentrations that exceed drinking water quality standards under natural circumstances, sometimes due to the type of rock through which the groundwater flows. It can be difficult to determine whether high chloride levels are due to natural or human causes.
Groundwater quality in the Otonabee Region Watershed was not graded in the 2013 Otonabee Region Watershed Report Card. A general statement on groundwater quality was included based on a review of the available data in comparison to provincial guidelines.
The Ontario Ministry of Natural Resources states that groundwater is an important source of drinking water for nearly 3 million Ontario residents. Groundwater is water that seeps into the ground from precipitation and is stored beneath the surface of the earth in aquifers which are areas composed of tightly layered sand, gravel and rock.
Groundwater is naturally replenished by surface water when the water seeping into the ground reaches the water table. Groundwater also flows (or discharges) to the surface through springs, streams and wetlands.
Threats to the quality of groundwater may be associated with:
- improperly maintained septic systems,
- leaking sewers,
- seepage from landfill sites,
- leaks from fuel or chemical storage containers,
- application of road salt,
- application of biosolids,
- excess use of, or spilled, fertilizers or other chemicals such as dry cleaning solvents, and
- livestock manure.
Wetlands contribute to a healthy environment, store water during floods and release it during dry periods. Wetland plants naturally filter contaminants from water and provide habitat that supports a variety of birds, amphibian and reptiles, many of which are considered Species At Risk, provincially and/or federally.
On a watershed or subwatershed scale, wetlands are commonly identified by Conservation Authorities through the use of GIS mapping resources. Most Conservation Authorities use Southern Ontario Land Resources Information System (SOLRIS) as the primary source of wetland cover data, however, due to inherent mapping limitations associated with SOLRIS, any measurement of wetland cover calculated using this resource is likely to be under-estimated.
Wetland cover was not graded in the 2013 Otonabee Region Watershed Report Card. A general measure and statement of wetland cover was included to illustrate the prevalence and importance of wetland cover in the Otonabee Region Watershed.