Alterations to surface and groundwater flows and volumes can have significant consequences for natural systems. Impervious surfaces that route rainfall and stormwater directly into brackish or saline environments can alter the salinity levels and corresponding vegetation communities at point discharges, while also limiting the capacity for groundwater recharge of the surficial aquifer. Water withdrawals from the surficial or deeper aquifers can result in reductions in the elevation of groundwater on a temporary or permanent basis. The lowering of the groundwater can result in saltwater intrusion into the surficial aquifer and the advent of detrimental salinity levels into historically freshwater systems. Lowered groundwater levels can also reduce the duration and elevation of inundation within freshwater systems through more rapid “leakage” of water from wetlands or lakes into the surficial aquifer. If extended over a long duration of time, the reduction in groundwater hydrology may result in the loss or significant degradation in wetland function. During cycles of drought, evidence of reduced hydrological function can be particularly apparent on the Island. This evidence includes lower pond levels, transitional and upland vegetation within historical wetland systems, and loss of canopy species. Regional influences, such as deep groundwater withdrawals for industrial uses on the mainland and potable water supplies, may impact groundwater levels on the Island although linkages between surficial aquifers and deep, confined aquifers such as the Floridan are not well understood in coastal Georgia. On an individual basis, surficial water wells used to irrigate lawns and other landscapes may have local scale impacts on surficial aquifer levels during drought. Historical infrastructure and development uses affect surface water routing, thereby influencing groundwater recharge as well as surface water inputs into wetland systems. From October 2012 through December 2013, the United States Geologic Survey (USGS) partnered with Jekyll Island Authority (JIA) to evaluate baseline conditions in the Island’s surficial aquifer. The resulting report is available here: https://doi.org/10.3133/ofr20161017. Additional studies would be beneficial to improve the understanding of the causes of the apparent reduced hydrological functions. Water saving conservation measures have been implemented on the Island, including low-flow appliances, cistern storage, and use of rainwater for flushing toilets (Hampton Inn and Convention Center) and irrigation (Convention Center). The golf courses, operated by the JIA, minimize water use through conservative irrigation management in accordance with the course-wide Audubon Cooperative Sanctuary certification. The 2018 Jekyll Island Carrying Capacity and Infrastructure Assessment concluded that the Island’s public water system, originating from five Floridan aquifer wells on the Island, is operating at under half of its permitted withdrawal capacity with year over year trends in use holding steady through 2017 (https://issuu.com/jekyllisland/docs/jekyll_island_carrying_capacity_and).
13 ENVIRONMENTAL SETTING
