Understanding the ups and downs, application of hydrologic restoration measures for a large Subtropical Lake.

Abstract

Hydrologic regimes in shallow lakes have a strong influence on the ecology and function of the system, and changes in water levels can have nonlinear disproportionate effects in these low gradient systems. When water levels are high, upper elevation littoral areas are impacted by flooding effects, benthic habitats are degraded, and nutrients are redistributed 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 providing the needed balance of water to downstream systems. The objective of this study is to evaluate LOSOM relative to ecologically significant performance measures. Overall, the proposed regulation schedule is expected to have deeper average lake levels, increasing the occurrence of damaging high stage events and reducing the frequency of low stage events. While decreases in the severity and frequency of low stage events will be beneficial, increases in high stage conditions 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.