The CLEAR Network - Thames River

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TOPICS OF INTEREST

Thames River Indicator Thames River Water Quality (Benthic Analysis)

Thames River

Thames River Indicators

Shared Accountability - Improving the Thames River

Thames River Water Quality (Benthic Analysis)

What Does this mean?
Why is This Important?
How Are We Doing?
Taking Responsibility - What You can Do
We Must All be Accountable - Improving Water Quality and Reducing Water Stressors - Find out More

What Does This Mean?

When the number of a particular type of "bug" is plentiful, it suggests a condition of water quality; some like cleaner water than others. Water quality can be measured in many ways depending on the purpose of the monitoring. When overall health of a watercourse is the purpose, then benthic monitoring is conducted. “Benthos” are the “beetles and the bugs” found living in the river. They are large, bottom dwelling insects, crustaceans, worms, molluscs and related aquatic animals that live in the river. They are good indicators of aquatic ecosystem health because they are sedentary (don’t move far), their life cycles are relatively short (ranging from a few months to several years), they are easy to collect and identify, they are responsive to changes in water and sediment quality, they are wide-spread, and they are not typically seen as an economic or recreational resource themselves.

Why Is This Important?

Using biological surveys such as using benthos, we are able to measure ecological effects. This is in contrast to water chemistry monitoring which is effective in monitoring conditions that put stress on the river (i.e., environmental contamination). Biological surveys are suited to impact assessment (i.e., determining the degree of biological affects in relation to some stressor), whereas water chemistry assessments are often used to establish the cause of known biological impairments or to assess compliance with regulatory criteria. Monitoring the benthic community has occurred in the city in the Thames River and tributary streams in 14 sites since 1992 with some historic assessments done in 1970 by the Ministry of the Environment (MOE).

The Family Biotic Index (FBI) is an assessment tool used by both the City of London and the Upper Thames River Conservation Authority. “Family” refers to the level of biologic identification that represents a range from least to most specific. “Family” is the term that describes the level of identification similar to other animals such as birds (e.g., bird, raptor or hawk, peregrine falcon). The existence of biota of a specific “family” in the watercourse suggests a degree of water quality or pollution that these species will tolerate. These results however are site specific and difficult to attribute to larger areas. FBI results are classified in general terms only (excellent, very good, good, fair, fairly poor, poor, very poor).

How Are We Doing?

æ Getting Better

The benthic communities along both branch locations (North and South Branches of the Thames River) appear to have improved slightly compared to historic benthic observations made 30 years ago in a 1970 MOE study. The Thames River running through the city is less healthy than rural areas of the river upstream however relatively healthy for a nutrient rich, warm water river environment. In 2004, a detailed benthic assessment was conducted associated with the Pollution Control Plant Discharge Study. It determined that:

South Branch of the Thames - There is some impairment to water quality on the South Branch of the Thames River likely due to a combination of factors including:

· Thermal impacts – warmer temperatures due to lack of vegetation shading the river

· Urban storm water – runoff from paved areas carrying pollutants related to city streets

· Treatment plant effluent – 2 pollution control plants are located along this branch

The North Branch of the Thames – It appears less affected than the South Branch and maintains good water quality through the city. Water quality is not severely degraded and appears to recover quickly at the downstream limits of the city. This recovery to “rural” impacted conditions of better water quality occurs fairly rapidly.

Compared to 1970, it appears that the general trend in water quality represented by FBI has improved slightly. This is however further explained by indicating that a general improvement in benthic community has been observed in several of the tributary streams that flow to the Thames River (e.g., Medway, Stoney). One of the benefits of benthic monitoring is that it responds well to trends of overall watercourse health. Improvements in both sewage treatment and storm water management have been made since 1970 when MOE performed initial benthic monitoring across the city.

Annual Thames River benthic reports are produced by the City to track local conditions of the river and tributary streams. These reports can be referenced from the City web site.

· Conserve water both inside and outside of your home

· Use a rain barrel to collect rain water for gardening purposes

· Install low flow shower heads and low flow toilets to reduce waste water from your home

· Use phosphorus-free laundry detergents

· Ensure Household Special Wastes are disposed of properly and do not enter the Thames River

· Respect the storm grates along the road by your house – they lead directly to the river

We Must All be Accountable – Improving Water Quality and Reducing Water Stressors - Find Out More

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