Clean water on Tennessee River.JPG

Huntsville Utilities' new treatment plant on the Tennessee River in Marshall County will initially produce 24 million gallons of clean water daily. (Eric Schultz | eschultz@al.com)

Huntsville Utilities is about to embark on the most expensive construction project in its 75-year history.

At its meeting Thursday night, the Huntsville City Council gave utility officials permission to build an $83.5 million water treatment plant on the Tennessee River in Marshall County.

Birmingham-based Brasfield & Gorrie has already been selected as the general contractor.

Scheduled to open in the summer of 2018, the new plant near Guntersville Dam will initially treat 24 million gallons of river water daily. As Madison County's thirst for water grows, it can be expanded to churn out as much as 96 million gallons.

Huntsville Utilities President and CEO Jay Stowe. (File photo)

Getting the clean water back to Madison County via new underground pipes - about eight miles worth -- will also be expensive. Huntsville Utilities President and CEO Jay Stowe said the total project cost rises to $115 million when related water system improvements are included.

Most of that money will be borrowed.

But the huge capital outlay is necessary to quench the Huntsville area's long-term water demands, Stowe told council members.

Even with two large water plants on the Tennessee River and several wells, the city-owned utility reaches 80 percent of its treatment capacity at times during the summer.

Councilwoman Jennie Robinson applauded the utility for building the plant now, before Huntsville is faced with water shortages like Atlanta and some other growing cities.

"It's a tremendous investment in our future," said Robinson.

Huntsville Utilities raised water rates in January 2013 to help pay for the mammoth construction project. The rate increase is adding $9.71 to the average residential customer's monthly water bill over a period of about four years.

Council President Mark Russell seemed a little uncomfortable that the new treatment plant, located south of New Hope in rural Marshall County, would rely on small volunteer fire departments for protection. Referencing the $50 million-over-budget Madison County Jail, he also asked Stowe to provide the council with monthly construction updates.

"So we'll know if it's not going so well," said Russell.

Stowe said the $83.5 million construction pricetag actually came as a pleasant surprise; utility officials had estimated the plant would cost $95 million.

This will be Huntsville Utilities' third large treatment plant on the Tennessee River, but the first outside of Madison County. The others are in Triana and near Whitesburg Bridge in south Huntsville.

Stowe said water system officials looked east to Marshall County because it offered the best combination of affordable land and excellent water quality.

Updated March 13 at 10:10 a.m. to correct that the treatment plant will be built south of New Hope, rather than east.