Trees, Rain Gardens and Barrels

Stormwater Runoff – How to Reduce Its Impact

Small streams in Nashville are characterized by a series of problems, found in most city streams, called urban stream syndrome.  The syndrome includes:
Quick rises in stream water levels during storms and more frequent flooding.  This is also called a flash hydrograph.

  • Elevated levels of nutrients and contaminants.
  • Altered channel morphology which means that the bank is eroding and/or depositing sediment more rapidly than expected.
  • Reduced biotic richness – not a lot of biological diversity is found in the stream.  The species that still live in the urban stream are pollution tolerant and begin to dominate the stream ecosystem, think of it as the stream equivalent of squirrels and pigeons.

Most of these impacts are linked to storm water run-off. That is, the water that flows down into catch basins in your neighborhood when it rains. That water flows into the nearest stream…rapidly and full of pollutants from the roof, yard and street. To solve the problem of storm water runoff we need to restore as much of the preexisting hydrologic system as possible. In other words, we need to increase the infiltration of rainwater into the ground. No, we don’t need to raze our cities. But we do need to give the rainwater a place to sink into after it falls. Technically, this is considered reducing our effective impervious cover.

The really great news is that we can help our small streams all the while making our yards more beautiful, saving money, saving energy and providing our gardens with healthier water. Maybe your grandparents used cisterns, if so you’ll be familiar with many of the ideas below that will improve our small streams. It is easy to get started.  We have descriptions, links and photos below. Plus, we have frequent workshops for hands on learning.

Goals and Progress to Date

The Cumberland River Compact and Metro Water are working together to oversee the planting of 10,000 trees and build 300 rain gardens.  This joint project will reduce storm water run off and improve water quality.  Most importantly, the citizens of Nashville will become stewards of their waterways.  Each tree and rain garden will be recorded and mapped.  If you’d like to help Nashville reach its goal, please contact  Follow the hyperlink, if you’d like to register your tree or rain garden.

Rain Barrels are used to harvest rain from the roof top.  We recommend that the harvested water be used for outdoor purposes only.  You might be surprised by the amount of water you collect:  one inch of rain on 1,000 square feet of rooftop creates over 600 gallons of water.

A rain garden is a shallow, constructed depression that is planted with deep-rooted native plants & grasses. Rain gardens slow down the rush of water from these hard surfaces, holds the water for a short period of time and allows it to naturally infiltrate into the ground.

Native plants provide the perfect habitat to attract and support local wildlife such as birds, butterflies, and other insects and animals that in turn provide pollination and natural pest control.  The shared geologic history of native flora and fauna established longstanding mutual relationships that also help gardeners.