Blog: City Blog

Reversing Trickle-Down Effects of Damaged Creeks

Before (left): Crews begin work on a segment of creek near Banks Avenue that was routed through an underground pipe in the 1950s.
After (right): A Stormwater Engineering project "daylighted" the creek to improve water flow and restore valuable ecosystems that ensure water quality.

Prior to tighter water-quality regulations that came about in the 1990s, ongoing development and city expansion led to the physical alterations of many of Knoxville’s natural waterways.

What seemed like harmless water-flow redirection at the time resulted in long-term cumulative damages that quite literally flowed downstream, such as:

   •   Erosion
   •   Flooding
   •   Damaged ecosystems
   •   Unnatural runoff
   •   Compromised water quality

For example, decades of silt deposits can change the depth of a creek bed, reducing the speed of the current, inviting heavy mosquito presence, inhibiting species survival, promoting algae and bacterial growth, and discouraging plant growth, leading to eventual bank erosion and flooding, and so on.

It’s the proverbial trickle-down effect of human interference.

“It’s comparable to how they describe surgery affecting the body - once you operate on one body part, odds are that you’re going to see other parts impacted,” said David McGinley, Stormwater Engineer. “Some of our flood plains, creek banks, and ecosystems are slowly deteriorating due to construction alterations that occurred decades ago.”

Over the last few years, the City’s Stormwater Engineering Division has completed several stream restoration projects to address these issues.

"Water quality improvement is the end game we are seeking with these restoration projects, though there are other benefits, such as bank stabilization," said Chris Howley, City Stormwater Engineering Chief.

Howley said the stormwater engineers have already observed some improvements in three projects recently completed. However, because the damage was caused gradually over decades, it will still be some time before the engineers can begin comparing true water-quality results.

Here's a quick rundown of Stormwater Engineering's recent stream restoration projects:

BANKS AVENUE
Neighborhood: Christenberry
Watershed: Second Creek tributary
Distance of Restoration: 200 feet
Completion: 2016
Cost: $84,000
Project Description: Nearly a half century ago, this tributary of Second Creek was rerouted into a pipe and covered. This project daylighted the stream and gave it a more natural stream condition. A riparian buffer (line of native plants) was installed along the banks to reduce pollution and stabilize the banks of the creek. This project was recognized with an Honors Award by the American Council of Engineering Companies Tennessee.

CAVALIER AVENUE
Location: Martin Luther King Avenue/South Chestnut Street
Watershed: Williams Creek
Distance of Restoration: 580 feet
Completion: 2017
Cost: $370,000
Project Description: Project relocated the stream and reestablished a natural flood plain (the area that is intended for water overflow). Wildlife habitats were restored and a riparian buffer was installed to stabilize the bank, prevent erosion, and filter pollutants.

SIMS ROAD
Neighborhood: Vestal/Montgomery Village
Watershed: Goose Creek
Distance of Restoration: 170 feet
Completion: 2017
Cost: $87,000
Project Description: Restored eroded portion of stream by stabilizing stream banks and installing riparian buffer.

For more information on the City's Stormwater Engineering Division, visit www.knoxvilletn.gov/engineering. To report a water quality concern, call 311.

Posted by On 02 April, 2018 at 10:45 AM