Could a small dam on Dry Creek ease flooding in Modesto area? Here are some options
A new report examines how erecting a small dam on Dry Creek might reduce its role in Modesto-area flooding.
Stanislaus County Public Works will hold a Jan. 18 open house on the idea. It does not have funding yet for the project, which could cost as much as $48 million based on the consultant’s work.
The report looks at 11 possible sites where Dry Creek might be impounded, generally in the Waterford area. It recommends four of them for further study, which the county Board of Supervisors could consider in the spring, Public Works Director David Leamon said in an email Friday.
The creek rises near the Stanislaus-Tuolumne county line, winds through rural stretches and enters Modesto near Briggsmore Avenue. It traverses Dry Creek Regional Park before joining the Tuolumne River near downtown.
At times, the creek is truly dry, a result of below-average rainfall years. It can reappear quickly, as with the late October storms. The stream contributed to the disastrous flood of 1997, which mainly involved the Tuolumne River.
The Modesto area has otherwise been safe from major flooding because of the vast size of Don Pedro Reservoir, completed on the Tuolumne in 1971.
Dry Creek is downstream from Don Pedro and has no flood control structures of its own. The four sites recommended in the report would have embankments 41 to 48 feet in height, tiny compared with the 585-foot Don Pedro Dam.
The 46-page report was done by the firm of GeoSystems Analysis Inc., based in Tucson, Arizona. The $250,000 cost was covered by a grant from the California Department of Water Resources, Leamon said.
The county could seek other grants for detailed engineering and construction, he said. There is no timeline yet for completion.
The project also could provide for recharge of the nearby aquifer, as the impounded water seeps into the ground in flood years. Stanislaus and other counties are under a state mandate to make groundwater supplies sustainable by about 2040.
The Jan. 18 open house will start at 6 p.m. in Harvest Hall at the Stanislaus County Agricultural Center, 3800 Cornucopia Way, off Crows Landing Road west of Ceres.
Details on the four sites recommended for further study:
- A 41-foot-tall dam near North Hopeton Road, about four miles east of Modesto. It would cost an estimated $47.9 million to build and could capture 746 acre-feet of water for recharge during a flood expected every 25 years on average.
- A 45-foot structure near Tim Bell Road, about four miles northeast of Waterford. It could cost $31.2 million and capture 423 acre-feet during a 25-year flood.
- A 47-foot dam about two miles northeast of the Tim Bell option. It could cost $20.9 million and capture 178 acre-feet during a 25-year flood.
- A 48-foot dam also about two miles northeast of Tim Bell. It could cost $18 million and capture 201 acre-feet during a 25-year flood.
More information is at www.stancounty.com/publicworks/storm/.
