PBS&J was selected by Hillsborough County to perform a study of the 240-square-mile Little Manatee River basin and develop a watershed management plan that would protect human health and safety and preserve the watershed’s aquatic resources. The plan addressed flood control, water quality, habitat, natural systems, and water supply, resulting in recommendations, cost estimates, and a schedule for implementation.
 
Initial tasks of the study involved an inventory of flooding and water quality problems, field survey of the existing stormwater management system, development of a stormwater quantity and quality monitoring program, delineation of subbasin boundaries, and development and calibration of hydrologic and hydraulic models of the watershed using HEC-1/HEC-2 and EXTRAN. The watershed model included 716 basins, 1,318 nodes, and 2,042 reaches. Water quality models were also used to estimate pollutant loading for each subbasin and major National Pollutant Discharge Elimination System (NPDES) outfalls.

PBS&J then developed conceptual alternatives and cost estimates to meet the County’s water quantity and quality level of service goals, and evaluated projects that could increase the County’s water supply or further the County’s habitat preservation goals. In an effort to manage stormwater from development within the watershed, PBS&J plotted water surface profiles and mapped the 100-year, 24-hour floodplain for the primary stormwater system in the basin. Other PBS&J assignments included preparation of a stormwater operations and maintenance plan, negotiation of a memorandum of understanding with the Southwest Florida Water Management District, and the creation of a project website to facilitate public awareness of the study.