I found an app called "realtide" that actually calculates the tide at your current location. You can even save locations like turners and look at it later. It seems to be pretty accurate.
Also go here
http://m.waterdata.usgs.gov/
You can zoom into biglake and there is a tide station right in the middle of the upper portion of the lake. You can can compare it to other stations and get a reading too.
The data location number is 08017095 Calcasieu pass is 08017118