The title of Douglas Adams’s Mostly Harmless could have easily been referring to the northern water snake (Nerodia sipedon). Spoiler alert: it isn’t. It’s about people. We’re way less harmless. since we’re mammals and wired with an instinctual mistrust for reptiles – snakes in particular – it’s understandable that many of us nonetheless have a visceral and negative reaction to the sight of them. I get it, and I feel it too. I promise if you encounter one it won’t end too badly. Sure, it’ll have a mouth, so it could bite you. But that’s extremely unlikely (unless you grab or otherwise harass the thing, in which case maybe you deserve it), and if it did you’d be faced with some mild pain and heavy bleeding while it slithered away. That’s not a license to go poking the creatures – they should remain as undisturbed as possible. I merely suggest that rather than screaming and/or running away the proper response to a sighting is to observe briefly and then move on.
The northern water snake is often mistaken for a copperhead (Agkistrodon contortrix) or water moccasin (aka cottonmouth, A. piscivorus), due to its brown, patterned body and similar overall shape. One way to clear up the confusion is to look for an “arrowhead” shaped head. However, the northern water snake may appear to have this head shape when in a defensive posture, so that can complicate things a bit. If you’re in Maryland, DC, or northern Virginia, you can be confident you’re not seeing a water moccasin because those don’t naturally occur here. However, the copperhead is fairly common throughout the mid-Atlantic and in my opinion looks a lot closer, too. It’s a good idea to be careful, especially if you can’t see the snake’s head.
I will admit that for most of my life northern water snakes hardly seemed worth my attention, with their dull, brown color and general snakeliness. When I’moved back to this area after college and started seeing them more regularly, I realized I’d been missing a treat. They’re one of the more easily found snakes and can often be seen basking near bodies of water, and their harmlessness makes them ideal candidates to study in the wild. I’ve come to see the beauty in their patterns of brown scales.
In this area I see them with some frequency around the ponds in Wheaton Regional Park and in various sections of Rock Creek Park. I believe, though, that they can be found near most natural bodies of water throughout the region. Like most snakes, they are accomplished at hiding, so investigating behind logs and in rocky crevices can be rewarding – but exercise caution when moving rocks, logs, stumps, etc. and always replace them as you found them.