STANLY, N.C — Despite some rain Tuesday, the Charlotte area is poised to enter the next phase of drought restrictions, this May, potentially imposing mandatory water conservation rules to protect our drinking water.
Nearly all the water we use in the Charlotte area comes from the Catawba River and makes its way through Duke Energy’s hydroelectric dams. That’s the same water we drink, that generates our power, that waters our lawns and runs our factories, so when that water gets scarce, Bryan Walsh, Duke Energy’s Vice President of Renewables and Lake Services says the system needs to prioritize its most important and most efficient uses.
“While hydro is a very cheap and efficient way to make electricity, it uses a lot of water,” he said.
It comes down to the drought response called the low inflow protocol. Walsh said it’s automatically triggered when the water system meets certain thresholds like low lake levels, high temperatures and low expected precipitation.
The Charlotte area is currently in the first stage of the low inflow protocol which calls for voluntary water restrictions. Should we hit stage 2, those restrictions become mandatory, recreational opportunities get limited and we even change the way we generate power.
“When we get to that point, then there’s mandatory conservation of water and definitely very large cutbacks in hydro generation to save water,” Walsh said.
That’s due to efforts to keep the water as clean as possible. When it gets churned up due to boating or large volumes moving through the hydro plant, that can stir up sediment and reduce the quality of the water in a way that wouldn’t be as much of a factor if the lake levels were higher.
To make up for the loss in hydropower, Walsh said we’ll likely rely more on the other stations around the Catawba Basin, like Marshall Steam Station or McGuire Nuclear.
“We’re always going to be able to provide electric generation which the majority of that can come from those thermal steam plants,” he said.
Those facilities use a substantial amount of water as well, but all of that water is recycled and returned to the lakes. During droughts however, Duke Energy has to work harder to make sure it’s not too warm.
“The more water you have in the lake the better it is to dampen the effects,” Walsh said.
When water levels drop, keeping that water cool requires more monitoring and attention to the plants’ outflows.
Yet, while hydro is taking a hit during this dry period, Walsh said one water-free generation source, solar, will likely get a lot of use this spring and summer.
“If you can pair solar with storage then you can try to save some of that energy to deploy during the highest demand periods,” he said.
The last time Charlotte imposed mandatory water restrictions was during the 2007-2008 drought. During that period, Walsh said the Catawba system entered stage 3 of its low inflow protocol for more than a year.