So far in this series, we’ve discussed the hydrologic cycle and wastewater management in Hamilton. We’ve learned the importance of preventing untreated wastewater and surface pollutants from reaching our waterways by maintaining the natural water cycle as much as possible. But what does that mean for the average homeowner?
As the mandatory outdoor water use ban for the city comes to a close, now is a great time to think about how we can use our yards to prevent our wastewater management system from becoming overwhelmed in the future.
What is a watershed?
First, it’s important to know what a watershed is, because it helps us understand where the water that falls in our yards (and anything it picks up along the way) will end up. A watershed incorporates the land—and anything built on that land—that eventually drains into the waterway in question. Since watersheds can be enormous, they are often broken down into subwatersheds for management purposes. These are defined by which tributary (a smaller river or stream that feeds into a larger river or lake) they flow into.
Simple diagram of a watershed, showing the receiving river and its tributaries. Watersheds are defined by land ridges that cause water to flow in different directions toward different waterways, as seen at the edges of the diagram. (Copyright © Be Water Friendly).
Since humans live on land, the biggest threats to the health of aquatic ecosystems start in their watershed. What this means is that when talking about managing a waterway, that includes managing the watersheds that flow into it.
The Hamilton Conservation Authority has developed Stewardship Action Plans that provide detailed information about what’s going on in each of Hamilton’s subwatersheds. Visit their website to learn about the natural and cultural history of the subwatershed you live in, how to be a steward of your watershed, and much more!
What’s the issue?
Last week’s blog talked a little bit about the importance of prevention. This means preventing untreated wastewater being released from Combined Sewer Overflows and preventing surface pollutants from flowing directly into the environment through storm sewers. In order to prevent both of these occurrences, we need to decrease the amount of water that reaches our sewer systems, and we can do this by being innovative in preserving the natural hydrologic cycle. Protecting natural areas is important to maintain groundwater recharge and stream baseflow, to prevent stream erosion and flooding, and to protect water quality.
This image shows the comparative amounts of stormwater runoff in areas of varying urban development (Copyright © Landscape for Life).
When urban areas are developed without stormwater best management practices in mind (think older developments especially!), large areas of vegetation are removed and replaced with large paved surfaces that are designed to quickly move water away. As populations continue to grow, watersheds will need more infrastructure to accommodate them, resulting in fewer fully natural areas. Since urban areas typically have an abundance of impervious surfaces, we have to get smart about development where natural areas are limited.
The guiding principle of Hamilton’s Stormwater Management Master Plan is to “Treat rainwater as a resource to be protected and managed, rather than a waste product to be quickly moved from where it falls”.
As mentioned in the last RAIN Blog, Source Control Measures are meant to soak up rain at the beginning of a watershed’s drainage system (i.e. where it falls!). When we incorporate these measures into urban developments, it is referred to as green infrastructure (GI) or Low Impact Development (LID). These are small and simple changes to landscapes that are designed to catch, store, filter, and evaporate rainwater on a per-property basis. They can easily be integrated into new developments, or added to existing properties. GI is meant to help urbanized areas mimic the functions of a natural area—that is, slowing water down, soaking it up, and keeping it clean.
Types of Residential Green Infrastructure
The following are some examples of green infrastructure that are commonly employed on residential property:
Rain Gardens (Bioretention) – These are shallow, bowl-shaped landscape features designed to collect stormwater and absorb it slowly. These will be explored in more detail next week, so be sure to check back next Wednesday!
Downspout Disconnection – This simple step will redirect stormwater runoff from entering the storm sewer system, and slowly infiltrate it through lawns and gardens, or direct it into storage (see below!)
Rainwater Harvesting – One of the most useful things you can do with a disconnected downspout is redirect it into a rain barrel! Collect and store rainwater to water your gardens later. Rain barrels will be explored in more depth on this blog in a couple of weeks.
Tree Planting – Trees absorb rainwater and return it to the atmosphere through evaporation, while keeping urban areas cool and supporting biodiversity.
Dry swales or Bioswales – These are shallow channels of rocks or vegetation that direct runoff through your yard and allow it to slowly infiltrate, recharging groundwater.
Xeriscaping – This is a creative form of landscaping that aims to reduce or eliminate the need to water yards. This method is often used when planning rain gardens, and usually includes planting drought-resistant native plant species.
Permeable Pavement – These are beautiful driveways, walkways, or patios that have gaps to allow rainwater to seep through rather than run off. This minimizes ice build-up in winter, decreasing the need for salt.
These are examples of residential green infrastructure. The image on the left shows a disconnected downspout redirected to a rain barrel, and the image on the right shows the bowl-shape of a rain garden installation in progress (Copyright © Green Venture).
Benefits of GI
- Flood-risk and property damage reduction
- Saves drinking water and money by decreasing the need to water yards
- Improved water quality
- Provides natural habitat for local wildlife like birds and butterflies
- Helps maintain baseflow and aquatic life in streams and wetlands
- Improved recreation opportunities
- Reduced urban heat island effects
- Increased property value
- Beautiful looking yards!
In the upcoming Summer RAIN Blogs, we’ll be exploring green infrastructure options a bit more in-depth, starting with our most recent rain garden installation through the Catch the RAIN program.
THIS AUGUST: Keep an eye out for our GI Video Tour, which will showcase some local examples of green infrastructure, highlighting individual stories and tips for how to get the most out of your yard!