Big Creek 
Big Creek in Hardin County, Illinois, is a beautiful, rocky, 
spring-fed stream supporting populations of three rare crayfishes 
(one of which is endemic to Big Creek), uncommon fishes, and 
relict populations of northern fishes. These organisms inhabit 
Big Creek because of its unique characteristics, most notably 
the large influx of spring water. Rare species in other taxono- 
mic groups (e.g. aquatic insects and annelids) are almost cer- 
tainly present but as yet uninvestigated. 
Among the species in Big Creek of special interest and impor- 
tance are: 
Orconectes species--an undescribed crayfish restricted in 
total distribution to Big Creek. A rather thorough investi- 
gation of other streams in southeastern I]linois and adjacent 
Kentucky hae failed to produce any specimens of this large and 
colorful species. Common in downstream riffles, Orconectes 
species is replaced in upstream habitats in Big Creek by 
Orconecteds kentuckiensis. 
Onrconectes kentuckiensis--a rare crayfish found in I1]llinois 
only in Big Creek and Peters Creek in Hardin County, and else- 
where only in a few streams in Crittenden and Union counties, 
Retry This crayfish is common in upstream pools of Big 
reek. 
Cambanus Laevis--a crayfish restricted in Illinois to a few 
spring-fed streams in Hardin, Johnson, and Pope counties. 
C. Laevis is also found in Indiana, Ohio, Kentucky, and West 
Virginia. 
Etheostoma kennicotti--the stripetail darter is restriced in 
Illinois to rocky streams in the Shawnee Hills. 
Etheostoma squamiceps--the spcttail darter is restricted 
in Illinois to rocky streams in the Shawnee Hills. 
AmbLopkites nupestris--the rock bass is restricted in 
southern Illinois to Big Creek, where a population is able to 
survive in the cool spring water. 
Micropterus doLomieui--the smallmouth bass is restricted in 
southern Illinois to Big Creek. Like the rock bass, this 
important game fish persists in Big Creek as a result of the 
low water temperatures. 
