The response of water level, flow, and shallow groundwater salinity to coastal wetland restoration in Taylor Slough, Everglades National park.

Evaluation of efforts to restore and protect coastal wetlands from degradation due to saltwater intrusion is vital because of the critical ecosystem services they provide. Rehydration of Taylor Slough and its associated coastal wetlands in Everglades National Park from past over drainage provides a valuable example of ongoing large-scale ecosystem restoration. Restoration since 2010 consists of infrastructure construction and a revised regional water management plan that integrates new with existing infrastructure. This work assesses the impact of these restoration efforts on hydrologic conditions and saltwater intrusion in Taylor Slough using monitoring data from 2000 to 2024. Double mass curves indicate a significant change in the rainfall-runoff relationship after 2015, coincident with testing of the new water management plan. Annual total managed inflows into the headwaters and flow exiting the headwater into central Taylor Slough increased by 2.0- and 1.8-fold, respectively, between 2000-2015 and 2016-2024. Relative flow increases were greater for the dry season (∼4x) than the wet season (∼1.5x). Additional water eliminated late dry season periods where marine stage exceeded freshwater stage within the freshwater-to-saltwater transition zone, likely halting saltwater intrusion in the shallow groundwater. Prior to restoration, salinization was observed in a 3 m deep well located in Central Taylor Slough at a rate of 0.11 PSU yr-1. After restoration, freshening was observed at a rate of -0.03 PSU yr-1 at the same well. Additional flow into central Taylor Slough also increased water levels and inundation days (∼80 days yr-1) and delivered an average of 27 × 106 m3 yr-1 more water to Florida Bay. Monitoring data demonstrates that restoration since 2010 has slowed saltwater intrusion and improved hydrologic conditions in Taylor Slough.