Low Water Dam study: consultants estimate $95–115 million range; bridge alone could cost $15–20 million

City staff and consultants updated the Jenks City Council on Aug. 19 about the Low Water Dam and pedestrian bridge study. Two technical workshops with partner jurisdictions, the consulting team and stakeholders have focused on construction methodology, gate types and bridge options.

Consultants recommended a construction‑manager‑at‑risk delivery to reduce unforeseen costs and said their review compared gate systems: rubber bladder systems (approximately a 30‑year lifespan) versus mechanical gates (estimated 75‑year lifespan). The group is analyzing lifecycle and maintenance costs as part of a longer‑term evaluation.

The pedestrian bridge concept discussed would span roughly 1,850 feet and be 20 feet wide; preliminary cost ranges for the bridge alone were estimated at $15–20 million depending on materials and configuration. The consulting team noted that soil borings needed for final design could not be taken immediately because river levels were currently too high.

Cost estimates for the overall concept have risen since the 2015 conceptual plan. Staff presented historical conceptual estimates of about $67 million (2015) and nearly $80 million (2017) and said preliminary assessments now place total conceptual costs near $95–115 million, including engineering and administration. The consultants plan a third workshop in late September and expect to deliver findings, recommendations and a 10‑percent design and cost estimate by February of next year.

Next steps: Additional workshops, geotechnical investigation when river levels permit, and a consultant report with cost estimates and recommendations due in February.