Tomball-area residents can expect to see the beginning construction phases of expanding the Cypress Rosehill stormwater detention basin by year's end, said Scott Elmer, the engineering department manager for the Harris County Flood Control District.

The current detention basin—located on the east side of Cypress Rosehill Road between Burkhardt and Seidel Cemetery roads—holds 44 acre-feet of stormwater storage, or roughly 14 million gallons, which run into the Willow Creek watershed. This basin was created to help mitigate the impact of widening Cypress Rosehill Road, said Michael Lacy, the project manager and vice president of KIT Professionals, at a June 27 HCFCD community engagement meeting.

Willow Creek at Hwy. 249 saw waters rise to nearly 3 and 4 feet above the top of the bank in the Tax Day and Hurricane Harvey floods, respectively, Community Impact Newspaper previously reported.

The proposed expansion, which is funded by the $2.5 billion HCFCD bond referendum passed in August 2018, will add about 25 acres of land to the east side of the current basin and provide a total of 140 acre-feet—about 46 million gallons—of stormwater storage. Lacy said this additional stormwater storage will reduce flooding risks in the Willow Creek watershed.

Elmer said the HCFCD expects to advertise for construction bids for the $3.4 million project in September, and construction will take about 180 days to complete, he said.