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Purple shade indicates vouchered specimens. Light blue (cyan) shade indicates photographic records. Yellow shade indicates verified sighting. Slanted hatch indicates pre-1980 records only

NOTE: Not all specimens upon which these maps are based have been verified.

Key Characters: Broad black bands or blotches on back; dark line from eye to corner of mouth; back scales strongly keeled; anal plate divided.

Similar Species: Northern water snake.

Subspecies: Broad-banded water snake, N. f. confluens.

Description: Large (up to 100 cm TL), stout snake. Back yellowish with 14-26 wide, black or dark brown blotches separated by narrow yellowish orange spaces. Sides marked with 20-35 black or brown blotches. Belly yellow, checkered with black or brown rectangular spots.

Habitat: Quiet backwaters and cypress swamps in extreme southwestern Illinois.

Natural History: A viviparous snake, it mates in April or May and gives birth to 15-20 young in late July or August. Newborn are 14-25 cm TL. Diet consists of fish and amphibians. Predators include other snakes and large shore birds.

Status: Endangered in Illinois. Threats include drainage of wetlands and removal of aquatic vegetation. May be extirpated from the only locality known in the state.