FRANKLIN, Tenn. -- The city of Franklin wants people to voluntarily restrict water usage due to the drought, and some residents said the drought is highlighting another water concern.

Video: Drought Affecting Franklin Water Supply

Behind the Harpeth River Dam, Franklin collects 20 percent of its drinking water. The rest of the city’s water supply comes from the Cumberland River.

The city is awaiting permits to complete a $7 million expansion to its pumping facility at the Harpeth River.

Pam Davee with the Harpeth River Watershed Association said that will drain an already strained resource.

When the area is having a shortage of rain, the Harpeth has little water flow, causing stagnant, dirty water. This results in low water quality and the need for more treatment for the population's drinking supply.

Davee wants the city to start getting all of its water from the Cumberland River, which would keep the Harpeth River's water levels high and cleaner.

However, Franklin Mayor Tom Miller said relying on the Cumberland River for their water supply would cost more, and the city is in need of a reserve water supply.