Hillsborough water customers, please continue to try to reduce water use by 10 percent. Voluntary water restrictions, which were established in September, are still in place.
Despite recent rains, the West Fork Eno Reservoir remains several feet below the water level set to allow construction to expand the reservoir.
“It will take a lot of rainfall to fully fill the reservoir to its pre-Phase II construction condition,” Hillsborough Utilities Director Marie Strandwitz said. “Imagine trying to fill up a swimming pool that is equivalent to 171 football fields in surface area. But this pool leaks, so you have to include extra water to see an increase.”
To maintain a minimum flow in the Eno River for water quality and aquatic life purposes, the town is required to regularly release water from the reservoir. The reservoir covers 227 acres, and its Phase I depth is 43 feet. It will be 53 feet after the expansion project is complete.
Before construction started in April 2018, the reservoir’s water level was lowered about 4 to 5 feet, an estimated 88 fewer days of supply, to allow the expansion work. It is currently about 8 feet below its normal level. When at its full Phase I depth, the reservoir has nearly 365 days of storage with a typical daily use of 1.1 million gallons and with minimum releases to support the Eno’s flow.
The West Fork Eno Reservoir now can be refilled to its Phase I depth as construction on a new spillway is complete. A related roads project still needs to be completed before the reservoir can be filled to its Phase II depth. The town is accepting bids through 2 p.m. Jan. 10 for that project to raise Carr Store and Mill Creek roads, which includes a bridge on Carr Store Road and a new culvert on Mill Creek Road. The reservoir is expected to be allowed to start filling to its new depth, about 10 additional feet, by the end of 2020.
The first phase of the reservoir was completed in 2000, and the permit included plans to expand the reservoir. Additional information is available on the project page on the town’s website: West Fork Eno Reservoir Expansion: Phase II.
Background on water restrictions
The reservoir expansion project and the lack of significant rain during the summer and fall are factors in the reservoir’s current lower water level. Below is a timeline of actions:
Early September ― Because the Eno River’s average flow had fallen below 10 cubic feet per second for seven consecutive days, a Stage 1 water withdrawal restriction was implemented, per voluntary agreement with the state and neighboring water providers. This meant the town could not freely withdraw as much water from the Eno as the town needed to support its operations and customer use. The Eno is the source of the town’s raw water, which is treated and distributed for drinking. The town managed the restriction internally by adjusting its water tank storage and by delaying its hydrant flushing program, which was to have started on Sept. 9.
Sept. 25 ― Due to continued lack of rain, the town implemented voluntary water restrictions for customers with the issuance of a proclamation. The fall hydrant flushing, which helps maintain the water system’s circulation and water quality by removing sediment from lines, was then canceled. Practices similar to those established in early September remained in place.
Early December ― The Eno withdrawal restriction for the town was removed due to more significant rainfall since mid-October, which has improved the river’s average flow. The town opted to continue voluntary use restrictions for water customers as the reservoir is still significantly below its Phase I depth. Water conservation and rainfall are both needed to replenish the supply. The rainfall to date has provided a net increase of approximately 1.5 feet to the reservoir’s water level.