Dirty Water: Why Are Knoxville Waterways So Filthy This Year? Blame the Heavy Rainfall

What does washing your car in your yard have to do with keeping fish healthy in your local lake? What does stenciling a rain barrel have to do with saving the planet? And if your golf game gets rained out this Saturday, why is it a good bet that your outboard motor propeller might get mangled on your next fishing trip?

The answers lie in "the water cycle," which you might remember from your childhood textbooks as an interlocking triangle of arrows representing moisture, evaporation, and precipitation. It was a diagram beautifully elegant in its simplicity.

Turns out it's a bit more complicated than that.

Think of your local watershed as a bathtub/shower combo, says Roy Arthur, the watershed coordinator in Knox County. You can fill the tub basin up by running the bath or the shower, but when you pull the plug, it still drains to the same source. Our local watersheds are slices of land and water that drain to reservoirs and tributaries and creeks and streams, which drain to the Tennessee River Basin. The Tennessee River is itself the largest tributary of the Ohio River system, which drains to the Mississippi.

Heavy rainfall can upset this system by sending large amounts of water into one of these bodies of water directly as runoff or by carrying in pollution in the form of sediment, topsoil, fertilizer, or other chemicals. It's like turning the shower on full blast while the tub is already three-quarters filled or continuing to run the water after you know the drain is clogged.

At the beginning of July, rainfall amounts in Tennessee were more than 15 inches above normal. We may be on track to break an unofficial annual record of more than 77 inches, set in 1875. That means that, in theory, the last time it rained this much, there were still relatively young Civil War veterans around worrying about their crops. Although we have the Tennessee Valley Authority's dam-and-reservoir system to rein in the flooding that wreaked havoc on local lands during their lifetimes, we have also lost an incredible amount of forest and farmland to development. Life in the modern world is a recipe for runoff, with lots of impervious asphalt, which lets stormwater race off in great sheets, and lots of cleared topsoil and chemical waste, which often make their way directly into streams.

What are the immediate effects of this heavy runoff? Dirtier waters. Long-term? The health of our waterways and water friends.

If you are boating on the main channels, you may see more trash bobbing along the water beside you, and once you hit the low-lying coves and inlets, you may run across stacks of flotsam and jetsam. The damage isn't just to your sensibilities or our streams: Knoxville-based East Tennessee Propellers, which repairs outboard motors, has seen a sharp increase in repairs this season due to refuse and sediment mangled and tangled in propeller blades.

Dirty water can also come from some of our favorite chemicals, says Arthur, who also works part-time at the University of Tennessee's Water Resource Research Center. He adds that many people don't realize that their storm drains drain directly into creeks, not into the sewer system. If you must lather up the Mustang with phosphate-filled suds, do it in the lawn, not in the driveway, where the chemicals can punch up the emerald on that green lawn. Fertilizers, too, can run off dangerously into our waters, as can any paint and oil and other chemicals that don't go to a designated disposal spot. Large-scale agricultural operations are at risk of fertilizer and waste runoff, but we also endanger our waters by not checking out failing septic and sewer systems and by not bagging up Fido's leavings at dog parks.

Sediment is the area's number-one pollutant, Arthur says. If a waterside development isn't sited properly, homeowners can actually lose part of their backyards to runoff and erosion, and if a contractor fails to secure materials on a job site, one good rain can take soil and rocks into the water. Longterm consequences include fish and aquatic populations that are choked out by stream fill, particularly those, such as the region's singular salamanders, that inhabit the crevices and cracks around rock.

Native vegetation can hold the soil in place, preventing sediment deposit and shading streams. Scientists have been taking a new look at the marvelously efficient way that trees and crops process stormwater, with one mature oak processing tens of thousands of gallons a year. Natural landscaping also helps your lawn absorb stormwater slowly, an essential part of the water cycle that gets short-shrifted around asphalt or hard-clay soil.

Mingling more of these plants into your regular landscaping—whether through a formal rain garden or not—will also benefit our waters, Arthur says. (The state-sponsored Tennessee Yards & Neighborhoods program gives nods to lawns that abide by these principles by recognizing "Tennessee Yards Done Right," a slogan that expresses green principles in a very down-home way.)

A paint-the-rain-barrel workshop won't put repurposed water back into your lawn, but taking one home with you makes it much likelier that you will eventually use it to irrigate your lawn and wash your car. Conserving rainwater in barrels for the driest months (typically September through November) and having gardens positioned to take advantage of stormwater runoff is something our grandparents did. While the actual shape of our waters has changed since their day, their common-sense solutions can be "retrofit" to our world, Arthur says, citing that as one of the popular environmental buzzwords of the day.

"We can't put them back the way they were—that's not even desirable," Arthur says of our waters. Instead, he says, protecting and rehabilitating area waters requires a mix of understanding and action. It's about figuring out what we do wrong and what we do right, then doing less of the first and more of the second.

It's also about talking about it, which is where our normally taciturn region has started to change. When people originally began looking at the region in terms of watersheds, which was about 15 years ago, Arthur says there were some segments of the public who reacted with "Don't tell me what they do in North Carolina." Today, though, Tennesseans managing Tennessee waterways have helped us equal if not surpass our neighbors across the mountain. Many also see a renewed spirit of cooperation among official authorities like TVA, data-rich knowledge bases like the UT, and ordinary business and homeowners.

Along with official state and county programs that bring everyone together to talk about reducing pollutants and monitoring hot-spots, there are also numerous community organizations devoted to sharing their knowledge of and love for our waters, including the Fort Loudoun Lake Association, the Harvey Broome Group of the local Sierra Club, and the Little River Watershed Association, which brings experts and the public together quarterly to cover everything you ever wanted to know about water and were hesitant to ask.

As befits the volunteers of the volunteer state, this area has also shown a great willingness to help our waters. Working through the organizations above and countless others, including church and school groups, volunteers fill the creeks and waterways in the spring and summer to capture and bag trash. While there may never be a shortage of refuse, particularly in a rain-soaked season like this one, it would be nice to be short a trash bag or several at the next such gathering.

"Everybody lives downstream of somebody," says Roy Arthur. "Everyone needs to understand how their actions affect our water."


51: average inches of rainfall per year in the Tennessee Valley

40-plus: inches of rainfall in the Tennessee Valley by the first week of July 2013

65: official record inches of rainfall in the Tennessee Valley, set in 1973

44: percentage of average rainfall that ends up as runoff

10: percentage of expected reduction in late-summer utility bills, thanks to extra hydropower

$2.4 billion: estimated cost in infrastructure to process runoff as efficiently as current vegetation on area ridgetops

$240 million: estimated TVA-prevented flood damage, annually

30: percentage of area waterways whose fish are not considered fit to eat

40: percentage of area waterways not considered safe for children to splash or eat in