Harmless · Native to the United States

Northern water snake

Nerodia sipedon (Linnaeus, 1758)

Also called common water snake, banded water snake
Data updated October 2026

Northern water snake basking on a log at the water's edge, showing dark crossbands on a brown body
Fig. 1 — Adult basking at the water’s edge, showing dark crossbands that break into blotches toward the tail.
Underside of a northern water snake showing reddish half-moon markings on a cream belly
Fig. 2 — The cream belly is marked with reddish or dark half-moons.

At a glance

A common, nonvenomous snake of creeks, rivers, ponds and marshes across the eastern and central US. It is often killed after being mistaken for a cottonmouth. It will bite and musk if grabbed but is harmless to people.

01

Identification

Northern water snakes are gray, brown or tan with dark brown, reddish-brown or nearly black crossbands near the head that break into alternating blotches farther back. Adults are often fairly dark; young snakes and wet snakes show the pattern more clearly. The scales are keeled, so the skin feels rough. The belly is cream or yellow with orange, red or dark half-moon markings. Like other harmless snakes in its range, it has round pupils.

  1. 01Bands, then blotches. Crossbands on the front of the body give way to alternating blotches on the back and sides toward the tail.
  2. 02Half-moon belly. Reddish, orange or dark crescents scattered over a pale belly.
  3. 03No pit, round pupils. It lacks the heat-sensing pit between eye and nostril that cottonmouths have, and it has no light line from the eye to the corner of the mouth.

Commonly confused with

The cottonmouth is heavier-bodied, with a bigger, chunkier head, a darker body, and a pale line from each eye to the corner of the mouth. Across much of the water snake’s range there are no cottonmouths at all: in the Southeast they are largely limited to the Coastal Plain, and they are absent from New England.

02

Size

01 ft2 ft3 ft4 ft Typical adult · about 36 in (91 cm)

Most adults measure about 2 to 3.5 feet (61–107 cm). Sources give ranges up to about 55 inches, and Missouri reports occasional snakes up to 59 inches. Adult females grow larger and heavier than males.

03

Range & habitat

Northern water snake swimming in a shallow rocky stream
Fig. 3 — Streams, ponds and rocky shorelines are typical haunts.

Northern water snakes occur through much of eastern and central North America. In the Southeast they live mainly in the Piedmont and mountains rather than the Coastal Plain. They use almost any freshwater habitat — creeks, rivers, sloughs, ponds, lakes, marshes and swamps — and rarely stray far from water. The midland form favors clear, cool, gravel-bottomed streams. Rock riprap along banks and levees gives them good basking and hiding spots.

04

Diet & predators

Water snakes hunt in and along the water for small fish, frogs, tadpoles, toads and salamanders. Healthy game fish are usually too quick for them; they take mostly small, slow, injured or dead fish, and some even eat discarded fish carcasses. Wildlife agencies note that this helps anglers by removing dead and dying fish rather than hurting fisheries.

Feeds on

  • Small fish
  • Frogs, tadpoles and toads
  • Salamanders
  • Dead and dying fish

Preyed on by

  • Large fish and frogs (newborn snakes)
  • Other snakes (newborn snakes)
  • Predatory birds
  • Predatory mammals
Green frog sitting at the edge of a pond
Prey — frogs.
American bullfrog in shallow water
Predator — large frogs (young snakes).

05

Behavior & seasons

Northern water snakes are often seen basking on branches over the water or on logs and rocks at the edge. If grabbed they bite readily and smear a foul-smelling musk, but they are not venomous. In hot weather they shift to hunting at night.

In Missouri they are active from early April through October. They spend winter in rock dams, levees, stream-bank and crayfish burrows, old logs and stumps, rock crevices, or underwater.

06

Reproduction

Northern water snakes give birth to live young. Mating takes place mainly from April through June, and young are born from August to October after roughly 2 to 4 months. Litters usually hold 20 to 40 young, but Missouri records range from 6 to 99, averaging about 27; bigger females have more. Males mature within about two years and females within three. They can live more than nine years.

07

Conservation

The species is not federally listed and is one of the most common snakes where there is good habitat. One island subspecies, the Lake Erie water snake, was listed as threatened in 1999 and removed from the federal list in 2011 after it recovered; at that time Ohio still listed it as endangered under state law. Elsewhere the main threats are wetland loss, declines in the amphibians it eats, and people killing it in the belief that it is a cottonmouth or that it harms game fish.

Keep reading

Sources

Data updated October 2026 · How we build these pages