The Central Everglades Planning Project (CEPP) serves as a framework for improving the quantity, quality, timing and distribution of flows within the South Florida ecosystem while also improving the water supplies available for irrigation and urban water use. One objective of the CEPP is to improve the distribution of inflows into northern Water Conservation Area (WCA) 3A, a regional wetland system within the remnant Florida Everglades. This requires major revisions to the hydraulic design of the L-4 levee and adjacent borrow canal located along the northern boundary of WCA-3A. Hydraulic modeling with HEC-RAS Version 6.1.0 was performed to evaluate the performances of four design alternatives: (i) a full levee degrade (to existing land surface) with the existing canal cross section intact; (ii) a full levee degrade with the L-4 canal cross section improved; (iii) conversion of the L-4 levee to a compound lateral weir along with the improved canal cross section; and (iv) the improved canal cross section with diversion culvert structures connecting it to a series of adjacent spreader canals. The performances of these four design alternatives were evaluated with respect to constraints imposed on the upstream canal stage along with selected performance measures used to assess the uniformity of lateral inflows along the northern boundary of WCA-3A. This process was repeated for a range of discharges into the L-4 canal at its upstream end. It was found that the design option 4 provided the most favorable distribution of lateral outflows into WCA-3A for all canal discharge rates evaluated, with spatial variations that did not exceed 10% along the length of the canal. Additionally, this option yielded the most favorable velocity distribution within the wetlands and was selected for final design.
