Water demand may outstrip supply within Duck River Watershed

Wednesday, October 14, 2009
James Smithey and his daughter Ashley enjoy fishing together on the Duck River near Halls Mill, a section of the river that, according to a TVA study, might not be able to meet future water demands from area residents.

A recent TVA study anticipates demand for water on the Duck River between Shelbyville and Columbia could outgrow supply.

However, a needs assessment study to be released next month by the Duck River Watershed Agency may help to address water supply issues that could develop in the future.

The agency already is working on a comprehensive water supply plan to address shortage concerns caused by drought conditions and how to meet future demands for Marshall and other counties in the Duck River watershed.

The TVA study, "Water Supply and Demand in Tennessee River Watershed Streams Below Reservoirs," was released in July. River agency executive director Doug Murphy says it's an examination of the tail water areas below the reservoirs that supply water to the region.

"The Duck River region from Shelbyville to Columbia was the only area in the Tennessee Valley that TVA highlighted as an area to expect future demand to exceed its current supply," Murphy said.

This study reiterated what was said in 2000 by another TVA report, "Future Water Supply Needs in the Upper Duck River Basin," Murphy said.

Recent projections by TVA and the U.S. Geological Survey indicate the Tennessee River watershed will add about 1.2 million more residents to the existing 4.7 million by 2030.

TVA also says that municipal growth in the region will increase pressure on the Tennessee Valley's water resources. Some already face water-supply challenges.

TVA first made water demand projections in 1979, Murphy said, and additional projections have been made by the University of Tennessee Center for Business and Economic Research (CBER) and the U.S. Geological Survey (USGS).

CBER used population projections and data on industrial growth, but when combined with the study from USGS, the region could see water shortages by 2010 to 2015 in a worst-case scenario.

"If we had a drought like we had in 2007, yeah, we could possibly start seeing some issues," Murphy said.

In that type of shortage, "we would really have to tighten down and do some mandatory restrictions for water use, operate the reservoir differently," Murphy said.

However, he stressed that computer models are still being run and that it's not possible to set a date and say "this is when we're going to run out of water." But, as demand for water grows and more water is drawn from the river without more supply provided, "then you have issues."

Also, the state mandates that a certain amount of water, measured in cubic feet per second, must keep flowing through the Duck to meet environmental needs. It's to accommodate wastewater treatment plants' effluent that's to be diluted by sufficient river water.

"We've got to prepare for future demand either by coming up with ways to manage the river different or to offering alternative supplies," Murphy said.

Murphy said they are looking "at about 30 to 40 alternatives," right now to boost the water supply -- "everything from pipelines to storing water in rock quarries or tributary reservoirs and storage facilities."

The 2000 TVA report presented several options for supplying more water to the Duck River, including:

* Transfer of water from Tims Ford Reservoir to Normandy Reservoir by pipe;

* Building another reservoir in part of the Fountain Creek watershed southeast of Columbia;

* Constructing a water supply intake on the Duck River downstream from the mouth of Catheys Creek northwest of Columbia; or,

* Raising the pool level of Normandy Lake.

At a river agency workshop set for Dec. 2, agency leaders hope to "weed out" some of the alternatives that are currently under consideration, Murphy said. The agency has traditionally met in the restaurant at Henry Horton State Park.