Manage Stormwater at Home for Clean Rivers and Habitat

rainwater mitigation with trees

It’s another one of those exceptionally rainy days (with more to follow) and I don’t want to do laundry or even take a bath. Why? A few days ago the city’s sewers overflowed into the river, and I’d rather not add more water to an already overtaxed system that results in raw sewage killing and polluting the habitat of wild species downstream. It’s not just the abundance of rain that’s the problem: It’s our infrastructure.

Generally, the unaltered earth is perfectly capable of soaking up or directing the moisture that nature doles out to natural waterways or floodplains (seasonal flooding is normal and natural). But our urban and suburban environments, with their ubiquitous and impermeable roads, walkways, roofs, and parking lots—as well as shortage of erosion-controlling plants—cause runoff that carries toxic pollutants like oil, fertilizers, and pesticides during heavy rains. In older parts of cities, pipes and tunnels that take away domestic and industrial waste combine with water collected from surface runoff. Under normal (not too wet) circumstances, the sewage and runoff is diverted to sewage treatment plants. But when too much storm water or snowmelt can’t soak in, it overwhelms the system, creating combined sewage overflows (CSOs) that cause raw sewage and other pollutants to spill into rivers, lakes, or coastal waters. People may be told not to have contact with the water, but wildlife suffers silently. Essentially, polluted sediments build up in waterways, increasing water temperature and turbidity and lowering oxygen levels, resulting in deaths.

In Portland, where I live, the city is investing in stormwater management projects that (sort of) mimic nature, in an attempt to mitigate stormwater at its sources. There is a plethora of work going on and CSOs are reportedly decreasing in frequency, but even one is too many.

How to help keep water clean

We can help manage and reduce stormwater pollution and overflows, starting at home. Here are some tips; some will have immediate effect, while others will take some time and effort:

Protect existing conifer trees and plant new ones (preferably those that historically grew in your area). A mature evergreen tree can intercept more than 4,000 gallons of rainwater each permeable hardscapeyear, about 80 percent more than deciduous trees. They also provide habitat, beauty, shade and cooling and help stabilize soil.

Renovate or construct new walkways, driveways, and patios with interlocking stones or other permeable paving, rather than concrete.

Disconnect your home’s downspouts when feasible and install rain gardens or swales in landscaped areas. They help prevent flooding by allowing water that falls on your roof to slowly infiltrate into the ground, lessening the burden on sewer systems when it is most important. Simply disconnecting spouts and allowing water to run down a driveway or walkway and into the street defeats the purpose. Additional rain garden guides: here and here.

swale from disconnected downspout Use only organic fertilizers when necessary (excess can be washed into waterways), and don’t use pesticides.

Grow native plants that help control erosion. Some examples (that naturally occur in many parts of the Pacific Northwest) include vine maple (Acer circinatum), madrone (Arbutus menzeisii), Oregon white oak (Quercus garryana), oceanspray (Holodiscus discolor), serviceberry (Amelanchier alnifolia), salal (Gaultheria shallon), nootka rose (Rosa nutkana), sword fern (Polystichum  munitum), kinnikinnick (Arctostaphylos uva-ursi), and inside-out flower (Vancouveria hexandra).

 Employ rain barrels to collect rainwater runoff from building roofs for irrigation during dry weather (if you can’t disconnect a downspout).

Conserve water simply by taking very short showers, never letting the faucet run unnecessarily, and fixing any leaks (just as you would during droughts!).

Collect “graywater” and use it onsite to reduce sewage discharges year round. Beware: this takes some ingenuity and planning!

 Never dispose of chemicals (like anti-freeze) by pouring it on the ground or into storm drains. Even drops of oil that seem relatively contained in your driveway can easily be swept into local waterways by rain. If you get an automotive oil leak, catch the oil in a pan and get it fixed ASAP.

© 2015 Eileen M. Stark

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