Iberia Parish presents $12.5 million recommendation of detention ponds and Far Canal cleaning to cut frequent T‑Bayou flooding

Iberia Parish officials and their engineering consultants on Monday presented a planning‑level drainage study for the T‑Bayou watershed that recommends a combined approach — upstream detention ponds plus cleaning of the Far Canal — estimated to cost about $12.5 million and to materially reduce frequent flooding in the watershed.

The parish president opened the forum by recalling last year’s damaging floods and saying the council chose a comprehensive analysis rather than short‑term fixes; he said the recommended package is “in the neighborhood of $12 million” and that the parish is pursuing CPA and GOMESA funding to pay most of the cost. The presentation then turned to consultant findings and next steps.

Consultants from FinsterMaker and Royal described the technical work that underpins the recommendation. Katie, a FinsterMaker engineer, said the team updated the watershed’s H&H (hydrology and hydraulics) model with new survey data, higher‑resolution LIDAR and the Atlas 14 rainfall curves, and performed a tailwater analysis. She said Atlas 14 increases the 100‑year rainfall depth by about an inch compared with older DOTD values, a change that matters for modern flood planning.

The team evaluated more than a dozen scenarios (channel widening, a diversion near Emil Veret, and upstream storage ponds among them). The recommended option combines storage ponds in the upstream T‑Bayou area with cleaning of the Far Canal. Consultants reported the pond scenarios provide roughly 200+ acre‑feet of storage across about 25 acres of surface area, remove roughly 500 acres of 10‑year inundation in the model, and lower water‑surface elevations at roadway crossings — with the maximum modeled reduction of about 14 inches at certain points along the channel.

Dax, a consultant who worked on the earlier T‑Bayou effort, provided historical context and cautioned about limits. He said previous modeling and field work showed dredging the downstream lake (referred to in the presentation as Lake Dotrief/Lake Do) moves downstream tailwater influence only about “a thousand or so feet” and is not a dominant factor for the broader watershed; he recommended focusing on upstream storage and on maintaining subdivision drainage systems. “Detention ponds work,” Dax said, noting municipalities and nearby parishes have seen local flood reductions where ponds have been put into service.

Residents and property owners used the open‑house format to press technical and local concerns. Multiple speakers pointed to a chokepoint at the Emil Veret bridge and to utility lines and built‑up banks that limit how much the parish can widen the channel without acquiring property or modifying bridges. Consultants said widening where right‑of‑way and utilities allow could show larger reductions (a model run noted up to about 19 inches in a constrained upstream reach), but that acquisition and utility relocation make such options less attainable, which is why ponds plus canal cleaning were recommended as the most practicable planning‑level solution.

The consultants and parish staff were explicit about limits. They said the recommended package is a planning‑level solution for more frequent events (the presentation focused on a modeled 10‑year storm) and that extreme ‘‘perfect storm’’ scenarios involving prolonged rainfall plus high coastal tailwater would require different, much larger measures (pumps, levees or coastal‑scale work) and are beyond the scope of this study.

Officials outlined the next steps: secure funding, complete a feasibility‑level analysis to optimize pond locations and control structures, proceed to design, and then to construction while continuing stakeholder engagement. The study authors also proposed updating FEMA maps and parish drainage ordinances to reflect the new modeling and to raise standards for future subdivisions so new development holds water on site.

Parish staff said land acquisition for ponds — often sugarcane or other open fields in the upstream watershed — will be a major hurdle, and speakers emphasized the project will not eliminate flood risk or remove the need for flood insurance. Organizers closed the session by making consultants and staff available for individual follow‑ups and by inviting residents to sign in for further outreach.

What’s next: the parish will pursue funding and move the study into a feasibility phase to test pond sizing, outfall control structures, downstream impacts and property/servitude needs before design or construction begins.