Watch this site, when salinity rises the fishing picks up. when salinity reaches 7 is when specs show up in numbers. but that is usually not till late summer as mentioned earlier.
http://waterdata.usgs.gov/nwis/uv?07387040
Also watch this one, when the river is at 9 or below is when the salinity in the bay starts to rise.
http://water.weather.gov/ahps2/hydro...lch&gage=blrl1
as you can see the river is at 15ft, which explains why salinity is so low.