95% of the time around our area if you see a snake in the water it's some subspecies of the common water snake...completely non-venomous.

As mentioned before there are several ways to differentiate a Water Moccasin from a common water snake - most easily identified attribute is the head shape. Common water snakes have no to a very slight head profile, where a water moccasin has a clearly spade and/or diamond profiled head shape. There are other identifying marks - see here:

http://ufwildlife.ifas.ufl.edu/water_moccasin_watersnake_comparison.shtml

Very beneficial read there if you're concerned. In the 30 years I've been around ponds in central and southern IL I've had a snake other than a common water snake or a garter snake show up twice.

And that'd be 2 times out of several hundred individual snakes.

Dale

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"When tempted to fight fire with fire, remember that the Fire Department usually uses water." - anonymous