This 87.5-acre (35.4 ha) Set-Aside Area is comprised of Rainbow Bay, a 200-m forested buffer area that encircles the entire bay, and a wedge-shaped corridor extending to a tributary of Fourmile Creek. This corridor was established to maintain a forested connection between Rainbow Bay, Bullfrog and Pickerel Ponds, and the Fourmile Creek drainage. Rainbow Bay is a 2.4-acre (1 ha) relatively undisturbed, isolated, wetland depression similar to a true Carolina bay, lacking only the geomorphological characteristics of a true bay (i.e, the northwest/southeast orientation and a sand rim).
The Rainbow Bay Amphibian Reserve Area is a Set-Aside which represents a relatively undisturbed bay/pond/woodland system in which herpetofaunal research has been conducted for nearly 20 years. This area has been used as a control site for Defense Waste Processing Facility (DWPF) studies and has been censused daily since 1978 for amphibians--more than 333,000 amphibians have been captured and marked to date. These studies have continued in conjunction with SRELís DWPF assessment and refuge pond mitigation research. Research at Rainbow Bay, the longest such study in the world, has been recognized by a National Academy of Sciences workshop as unique and extremely important for addressing concerns on the global decline of amphibians. Within the nearly 20 years of daily monitoring of Rainbow Bayís drift fence by SREL personnel, less than 20 days have been missed in this one-of-a-kind census effort. Studies from this Set-Aside Area helped initiate the expansion of the SRS Set-Aside Program in 1989, primarily as a result of research that suggested that large buffer zones are necessary to preserve the terrestrial environments for amphibian species. In addition, Rainbow Bay represents the only Set-Aside bay that is surrounded in its entirety by a forested buffer zone; it also is the only Set-Aside bay whose buffer area has not been subjected to clear-cutting or prescribed fire for over twenty years. Historically, this Area has served as a control for other bays which may have been subjected to various impacts related to Site operations.