I know where they come from, so already pretty dated. A snake being listed in a county isn't particularly exciting. It is handy to know they are recorded in the county, but then you have to know their habitat.
Take Dallas County--Rat snakes and copperheads are a dime a dozen, and they can be reported anywhere in the county. Go to anywhere around Joe Pool/Cedar Hill SP, rattlesnakes may be about the most commonly spotted snakes (Cedar Hill SP has a crap ton of rattlesnakes). But outside that escarpment zone area of southwest Dallas County, you don't find rattlers. There are some legit Cottonmouths throughout PARTS southern Dallas County. I get tons of cottonmouth sightings around White Rock Lake, we'll just say they are as legit at the mountain lions.