NEW PORT RICHEY — A portion of the Duck Slough watershed that caused major flooding this summer in Trinity's Thousand Oaks neighborhood could soon be designated as a "basin of special concern."
County commissioners on Tuesday gave initial approval to such a designation for a 7.5-square-mile tract in the basin. The move would essentially require higher stormwater design standards for future development to avoid compounding the flooding problems.
"It does not solve the problem, but I believe it will keep it from getting worse," said county engineer Jim Widman.
Currently, developers must design drainage systems to handle the type of storm that occurs once every 25 years. The new rules would require designs for a two-year, 10-year, 25-year and 100-year storm.
Commissioners must still hold two public hearings in December before the "special concern" designation takes effect. In the meantime, county officials are devising a plan to improve the current flooding concerns.
The chief cause of the flooding, Widman said, is that heavy groundwater pumping left the water table artificially low when development in the area was approved in the 1980s.
Stormwater was routed to the development to refill wetlands that were severely dehydrated. Groundwater pumping has dramatically decreased since then, however, and the water table has risen. Combined with vegetation growth inside the wetlands, high flood waters now overwhelm weirs and other stormwater control devices.
An earlier plan called for dredging a canal through those wetlands to improve the drainage. County officials still plan to apply to state and federal officials for such a permit. But that would require the county to provide costly mitigation projects to offset damage to the wetlands.
Widman said he has devised five alternatives that would avoid cutting a canal through the wetlands. Officials will discuss the pros and cons of each plan at a neighborhood meeting Nov. 5. The options all involve building culverts from the wetlands in Thousand Oaks to take water to a system running west along Mitchell Boulevard. The plans are still conceptual and have not yet been fully designed.
Officials hope to select the best alternative by mid December. The county will match an $875,000 grant from the Southwest Florida Water Management District to design the project. The county would then seek grants for construction money.
Commissioner Jack Mariano pushed county staffers to try to override environmental concerns about the solution that relies on wetlands dredging. He called Widman's alternatives a "Band-Aid approach."
"I think we need to go to our federal people, get them to the table and get them to push this thing forward," he said.