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

Abstract

Hydrologic regimes in shallow lakes strongly influence 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 significant 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 beneficial, 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.

Upstream Water Management and its Role in Estuary Health, Evaluation of Freshwater Management and Subtropical Estuary Function

“…While discharge volumes did not change signi cantly between baseline conditions and the preferred alternatives for the CRE, the combined effect of the C-43 reservoir and changes to operational rules helped modulate discharges to the estuary reducing stress and damaging discharge while improving optimal conditions. This change in discharge regime for the preferred alternative is a combined result of water management rules (when and where) and restoration infrastructure (how) such as the C-43 reservoir for the CRE (Julian and Welch 2022).…”