Understanding the ups and downs: application of hydrologic restoration measures for a large subtropical lake

Abstract

Hydrologic regimes in shallow lakes strongly in uence the system's function and ecology. Changes in water levels can have nonlinear, disproportionate effects in these low gradient systems. High water levels can submerge upper elevation littoral areas, degrade benthic habitats, and redistribute sediments and nutrients throughout the lake. When water levels are low, wetland littoral areas are dried out, prompting shifts in plant communities. Lake Okeechobee, a large shallow lake, is a diverse and complex ecosystem managed for multiple purposes. Currently, water levels within the lake are managed based on the Lake Okeechobee Regulation Schedule of 2008, which is being replaced due to the completion of key restoration projects. The new regulation schedule, Lake Okeechobee System Operating Manual (LOSOM), updates water management rules while attempting to balance the needs of downstream systems; salinity and water quality in the Caloosahatchee and Saint Lucie estuaries, and more water for the southern Everglades. This study evaluates LOSOM relative to ecologically signi cant performance measures for the lake. Overall, the proposed regulation schedule is expected to cause deeper average lake levels, increased occurrence of damaging high-stage events, and reduced frequency of low-stage events. While decreases in the severity and frequency of low stages will be bene cial, increases in high stages may impact the long-term ecology of the system. As lake management shifts to optimize restoration efforts around and downstream of Lake Okeechobee, restoration projects upstream of the lake become critical to building and improving resilience in this central South Florida ecosystem.