6 Salinity timeseries

Salinity has been monitored at multiple sites in Gilbert Bay approximately every 4-6 weeks under consistent field and analytical methods by USGS since 2010. A deep brine layer (DBL) was present from 2010-2014 (Figure 6.1). The DBL was observable at two sites with the northern site (2601) showing higher salinity than the southern site (5601). Following culvert closure (2014-2017), the DBL dissipated, and surface salinities in Gilbert Bay increased. The DBL reformed in summer/fall 2017 following the opening of the causeway breach. Surface salinities in Gilbert Bay decreased by about 40 g/L (4 percent) following the causeway breach opening.

Figure 6.1: Gilbert Bay salinity for surface (<=1 m) and bottom (>=4 m) samples for all USGS monitoring locations in Gilbert Bay. Data from USGS NWIS.