Guelph is fortunate in that our water supply comes almost exclusively from groundwater, water that comes from rain and melted snow that seeps down through soil and cracks in rocks and refurbishes the two aquifers which supply our water, water which Guelph citizens have made clear they want protected.

The only problem is the way we have been building our cities and managing our stormwater, using concrete curbs and asphalt roads and parking lots, is costly and allows salt, oil, grime and chemical pollutants to run off and make their way back into streams and sometimes into groundwater, causing sedimentation and erosion along the way. This type of urbanization has also contributed to species extinction by interrupting links between ecosystems and disrupting migration corridors.

As we look to develop Guelph’s last green field area in the south end, the Clair-Maltby region, with its lush rolling hills and woodlands, and Guelph’s second largest provincially significant wetland, Halls Pond, all of which serve the function of recharging the groundwater and three streams, we need to get it right and build a community where the environment and groundwater are both protected.

Fortunately there is a new and better way to manage stormwater, even in times of heavy rainfall, save the city money and protect the environment at the same time. Sound too good to be true? Many communities in and around Guelph and in the United States are using a method called low impact development, a part of green infrastructure, to reduce the need to build and maintain costly grey infrastructure and to extend the life of what we already have.

Low impact development mimics a site's natural hydrology and returns stormwater to the ground, largely on site, using one or several natural features or installations such as green roofs, permeable pavement, infiltration trenches, rain gardens, bioswales, urban trees, and active turf and grasslands to serve this function. Green infrastructure not only saves and protects water from contamination but also importantly reduces carbon emissions which contribute to global warming, beautifies the environment and can even increase property values, create jobs, protect wildlife by improving habitat connectivity, and create healthier communities.

Engineering techniques have been developed to enhance the natural functions of trees and planting beds to maximize their ability to allow water to infiltrate and be cleaned of pollutants while finding its way back to groundwater. For example, special structured soils can be used where trees are planted.

The Toronto and Credit Valley Conservation Authorities, which have been successfully utilizing these techniques, have produced guide books to help other cities learn from their successes and failures and how to construct such installations as enhanced grass swales, rain gardens and tree plantings that are effective. Guelph is lagging behind other nearby communities in employing these techniques.

Instead of having concrete curbs along paved roads, ribbon plantings can be made so that the curb slopes down into them where special soil types will absorb the water or into infiltration trenches filled with aggregate. When a rain garden is built, large holes or depressions in the ground are dug and filled with layers of fine sand to filter the water and with compost topped by plantings of native species plants surrounded by hardwood mulch to prevent erosion.

Rain gardens can be built near roads to divert rainwater into them or near buildings or homes. The rain garden in my backyard keeps the rain away from the foundation of my house and prevents it from entering the drains in the road, plus the native species plants are watered by the run-off. First Baptist Church on Woolwich Street has two rain gardens in front that restores all the run-off from its steep roof back to groundwater.

Many public and commercial buildings are now installing either shallow green roofs or intensive deeper ones capable of producing food and returning moisture to the air by leaf transpiration. These green roofs will reduce the buildings’ energy consumption therefore reducing the need for expensive air conditioning. Toronto has now passed a bylaw requiring all industrial buildings with rooftops over 20,000 square metres to have a green roof. Ryerson has a green roof in full food production. In New York there is a 50,000 sq. ft food production green roof. Think how these could take a load off of food banks.