Thanks for all the great info. I am quite a distance upstream from what could possibly be brackish water. One possibility is salt(brine) contamination in the gully. The site is on top of a once sulfur producing salt dome. They now preform solution mining to produce brine water for local industry.
Here is a link to the spot where the traps are being set. (Green arrow)
GPS:
30.248827, -93.405845‎
+30° 14' 55.78", -93° 24' 21.04"
https://maps.google.com/maps?hl=en&q=30.248827,-93.405845&ie=UTF-8&hq=&hnear=0x863b8cdeb034b5ed:0x8cd2e59f8fe5b369,%2B30%C2%B0+14'+54.24%22,+-93%C2%B0+24'+14.20%22&gl=us&ei=SvFpUIb8JsfNqQHo_YCwDg&ved=0CB4Q8gEwAA
My main pond is to the east of the green arrow and the livestock pond is to the south. If you zoom out a little, you can see the large ponds that drain through this gully to the north and west.
I was mainly interested in adding them because they were there and free. I currently have an abundance of Gambusia, which entered the pond naturally, my CNBG seem to be growing great and I recently stocked FHM along with RES and things are looking good for the stocking of Florida LMB this spring.
