Magnolia Valley is located in Pasco County, Florida, within a 960-acre sub-watershed extending from Little Road to Rowan Road. Numerous small lakes are scattered throughout the area and receive runoff from local stormwater collection systems serving the surrounding residential neighborhoods. Past flooding in the area results from storage and conveyance deficiencies, and local streets are inundated with some frequency. Historically, under more severe storm conditions, area lakes have exceeded their banks and residential structures have been flooded.
DES developed a set of Best Management Practices (BMPs) designed to reduce the frequency, depth and duration of flooding in the community. BMPs consisting of conveyance improvements (e.g., pipe sizing) have been proposed to provide 10-year level of service for roadway flooding and 100-year level of service for structural (residential) flooding, where practicable. No significant opportunity to provide additional storage within headwater areas or in the immediate vicinity of existing flooding sites was identified.
The proposed conveyance improvements will result in some change in delivery of stormwater being passed downstream toward the Magnolia Valley Golf Course. Although flood durations on the golf course are not expected to increase significantly, assuming pump operations are not changed, the upstream improvements may cause small increases in peak water surface elevations on the golf course. While no specific sites have been identified for acquisition and conversion to retention ponds on the golf course, two candidate sites were evaluated and were shown to mitigate those minor stage increases.
With some refinement to address permitting requirements and ownership/easement constraints, the proposed drainage improvements comprise a stormwater management plan to mitigate flooding in Magnolia Valley. The plan could be taken forward to receive conceptual permitting approval through the Southwest Florida Water Management District.