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Thursday, Mar. 5, 2015

Grow with the flow: DRA hopes to keep water supplies adequate

Sunday, August 15, 2010

(Photo)
Raising the winter pool of Normandy Reservoir during the winter months is just one of the recommendations from a Comprehensive Regional Water Supply Plan that will be before the Duck River Agency's board in October. The public is invited to comment on the recommendations at Henry Horton State Park on Sept. 9.
(T-G Photo by Brian Mosely)
Recommendations to increase the capacity of Normandy Reservoir, along with other water saving ideas, are to be presented to the public next month by the Duck River Development Agency (DRA).

On Wednesday, DRA held its final workshop to work out a Comprehensive Regional Water Supply Plan for Bedford, Coffee, Marshall, Maury, and southern Williamson counties.

The DRA has been working on the plan for over a year now, according to executive director Doug Murphy, and the plan addresses water needs for a planning period of 50 years, while looking forward 100 years down the road.

The recommendations are:

*Raise the winter pool of Normandy Reservoir by five feet to increase water storage for use during droughts and boosting flood protection.

*Implement a water use efficiency program.

*Develop a regional drought management plan.

*Optimize the releases for Normandy to preserve storage in the reservoir for when its needed the most.

*Relocate Columbia's water withdrawal to a new intake approximately 25 miles downstream where an adequate flow exists during droughts to satisfy projected needs.

A public meeting is due to be held on Sept. 9 at Henry Horton State Park so citizens can comment on the recommendations, although the exact time has yet to be worked out.

Murphy said there will likely be two public sessions that day to allow time for all to participate. Comments from the public will be incorporated, as appropriate, into the plan, and the DRA board will then vote whether to endorse the plan in October.

More capacity

The first project would involve working with TVA to change the flood guide operation for Normandy Reservoir.

Currently, the winter pool level is 864 feet above sea level and the recommendation is to raise that by five feet. Murphy said that this could be done in increments or not even go up the full 5 feet. Summer pool level for Normandy is 875 feet.

However, filling the lake more in the winter means more space would be needed for seasonal flood storage, and that leads to having to raise the dam and the capacity of the reservoir.

Murphy said putting that much water into the winter pool would add five billion gallons of water to the reservoir, which would get the region through a multi-year drought and keep flows into the Duck River for a longer period of time.

Normandy does not fill every summer, and Murphy said that computer models showed that raising the level would give the region extra water.

Another option is to look how the reservoir is managed and if there isn't enough room to hold flood waters in the spring months, then factors downstream would have to be examined, looking at frequency and duration of flooding.

Raising the level during the winter months would also prevent impacting the shorelines of the lake, Murphy said, but added that the flooding frequency and properties around the reservoir would be impacted some in the spring.

"You'll have more flood events, they may be a little bit higher than they are now, so we've got to look at all the structures and all the impacts around Normandy Reservoir," Murphy said, such as roads, campgrounds, and personal water use facilities.

Managing water

Plans that would go into effect within the next fiscal year involve developing a drought management plan for the region, Murphy said.

The plan would only be used depending on how severe any future droughts are, but a good plan is needed for Normandy "to prolong our water supply to meet all needs," he said. He expected work on this would begin in the fall.

The water use efficiency program is another non-structural component of the plan, with Murphy commenting that "I'm not sure we know how we use our water, and if we're using it wisely."

This isn't just about how utilities use water and send it to your home, but also how residents and commercial customers use it and how they can use it more efficiently, he said.

Murphy even suggested that "it maybe will change our lifestyle a bit," adding that there would be a lot of education involved in this aspect of the plan.

The other "non-structural" part of the plan is to optimize the releases from Normandy Lake, which means making sure that TVA has the best tools, gauges and forecasts to operate the reservoir as efficiently as possible.

"We don't want to waste water, we want the water in the river to meet all needs, but TVA has to do a better job," Murphy said, adding that a lot of agencies will be involved in this part of the plan helping to develop the program to optimize the releases.

All of these programs would be implemented over the next three to five years, Murphy said, and "would serve our immediate focus."

Columbia intake

The third project looks downstream in Maury County, where the intakes for Columbia would be moved downstream some 25 miles where there is more water in the Duck River. About 17 miles of pipeline would be needed for this project.

Murphy said if the Normandy project could be done first within the next 10 years, this would help the region through an extended drought period and would meet the growth that is expected over the next 10 to 40 years.

By moving the intakes in Maury County downstream, "that increases their water capacity by a significant amount," Murphy said. Flow studies have not been done, but indications are that it could mean getting twice the amount of water from the river.

"When we see growth, that's when the intake should be moved downstream," he said, adding that this part of the plan may not happen for 10 or 20 years, depending on the housing market, the economy and how it will impact growth.

The cost

Multiple components of the plan will be addressed over the next 50 years, Murphy said, such as population growth and drought spells, adding that one plan won't fix all the long term needs of the region.

"When we mean a 100-year vision, we're really stretching it ... we're going to be working on this for a long time," Murphy said.

Murphy says that DRA is now in the implementation phase, and he says work needs to be done in completing a financial plan.

The estimated cost for the recommended plan is $62 million and more technical and environmental investigations are planned to refine the costs.

Murphy stressed that the financing approach is "growth pays for growth," where new customers would pay a one-time system development charge to offset the costs of the new infrastructure.

While rates and charges are still being developed, the proposed approach would cost current customers no more than $1.50 per household per month.

"Working together works" is another aspect of the plan Murphy stresses, saying that "as a Duck River region working together, we can make it affordable."

A year in the making

Close to 50 people from different agencies have participated in the meetings over the last year, reviewing the recommendations and providing comments from the various organizations involved.

The drought of 2007 highlighted the issue of the region's water needs, since citizens of the Duck River area depend primarily on Normandy Reservoir for much of their supply.

The drought caused record low levels in the reservoir that resulted in temporary changes in the operation of the dam to protect water uses. The weather, combined with regional growth projections, created the need for the water supply plan.

The first step of the plan was to learn what the area's water needs would be through the year 2060, using computer models of the operation of Normandy Reservoir and the Duck River's hydrology.

Population projections were used to determine what the water demands would be and the study indicated that there is a deficit of up to 32 mgd (million gallons a day.) Approximately 4 mgd of this deficit exists today and the remaining amount will result from the regions projected growth.

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.

Around 40 alternatives to addressing the water supply needs were examined, which were reduced to 26 that were considered worthy of consideration over a period of six months. Those options were studied extensively and narrowed to the final five recommendations.