We operate seven reservoirs that support the operation of municipal wastewater treatment plants. Water from the spring runoff is stored in the reservoirs and then released gradually through the summer and fall to meet flow targets at specific locations. This ensures there is enough water in the river system to receive the treated effluent from the plants.
Wastewater
There are 30 wastewater treatment plants in the Grand River watershed. They are operated by 11 municipalities and two First Nations.
The plants handle the waste from more than 600,000 people - about two-thirds of the population of the watershed. Most of the rest rely on private systems, such as septic tanks, to handle their waste.
Treatment plants serving five cities (Brantford, Cambridge, Guelph, Kitchener and Waterloo) handle about 90 per cent of the wastewater.
The plants remove about 95 per cent of the pollutants from the wastewater. Once the treated effluent is released into a river or stream, natural processes carry on the treatment process.
Plants and algae in the river absorb nutrients such as phosphorus and nitrogen. As the water tumbles over rocks and through rapids, it is aerated - i.e. it takes in oxygen - which aids the breakdown of some pollutants. Naturally occurring bacteria consume some organic material.
However, there are limits to the ability of rivers and streams to process, or assimilate, the wastewater plant effluent. This is called the "assimilative capacity" of the waterway.
The volume of pollutants remaining in treated effluent from one plant is small. However, the combination of the effluent from 30 plants adds up. The result is that in the Grand River, water quality generally deteriorates as the river flows downstream to Lake Erie. That has an impact on water quality in the river and the lake.
Regulation of wastewater treatment
All wastewater treatment plants operate under regulations established by the Ministry of the Environment, Conservation and Parks. A plant must have an Environmental Compliance Approval, which sets out rules of operation to protect the environment.
Improving wastewater treatment
As populations grow, municipalities and the province work to improve wastewater treatment plants and their operation to reduce the impact on the river system.
Plant upgrades
Many wastewater treatment plants have been upgraded or are being improved to handle growing population and to raise the quality of the treated effluent they release. For more information, visit municipal websites.
Plant operations
Municipalities are improving the operation of their plants to produce cleaner effluent from existing equipment. This is a process known as "wastewater optimization." For more information go to the Wastewater optimization section.
Wasterwater treatment plant bypasses
Occasionally, untreated or partially treated wastewater is released from a wastewater plant, pumping station or other part of the wastewater collection and treatment system. Managers of municipal water and wastewater systems analysed the causes and responses to these spills and bypasses. The result was a document outlining ways to reduce the number and effect of the releases.
Please note the following documents may not be accessible to people with disabilities. If you have a disability and require a document in an alternate format, please contact us.
The Grand River Watershed Water Management Plan outlines the steps being taken by the GRCA, municipalities, senior governments and First Nations to address many issues including water quality in the Grand River system and Lake Erie.
Please note the following documents may not be accessible to people with disabilities. If you have a disability and require a document in an alternate format, please contact us.
As part of the Water Management Plan, a report, Assessment of Future Water Quality Conditions in the Grand and Speed Rivers (1.4KB PDF), was prepared predicting future river water quality based on proposed upgrades to wastewater treatment plants and optimization efforts. A Case Study (363KB PDF) also highlights this work.
Understanding and forecasting water quality conditions
It is important to understand changes in water quality and to be able to predict how various factors such as population growth, wastewater plant upgrades or optimization will affect water quality in the future.
The Grand River Simulation Model (GRSM) is a computer model of the watershed that is used to analyse conditions and trends. Go to the River modeling page for more information.