Island Park reservoir is an Irrigation storage reservoir that?s on the Henry Fork of the Snake River. Two small creeks, Sheridan Creek and Icehouse Creek enter the reservoir on the west end. Surrounding habitat varies from coniferous forest to shrub-steppe. Draw-down during summer exposes extensive mud flats that support good numbersof migrating shorebirds and other waders. Large numbers of waterfowl also stage on the reservoir and some species gather in large numbers for post breeding (prealternate/eclipse) molt (e.g., Gadwall).
During the fall, this site is used by 2000+ ducks and geese, over 1500 Franklin?s Gulls, and large flocks of migrant songbirds that use the willows on the west end of the reservoir. During the breeding season, Goose Island is used by a variety of colonial waterbirds, including Ring-billed and California Gulls, Caspian Terns, Great Blue Herons, Double-crested Cormorants, and Black-crowned Night-herons. Other Species of Concern that breed here include Sandhill Crane, Boreal Owl, Lesser Scaup, Western Grebe, Wilson?s Phalarope, and Forster?s Tern. In addition, the following Species of Concern are suspected to breed here: Swainson?s Hawk, American Avocet, Long-billed Curlew, Franklin?s Gull, Short-eared Owl, and Brewer?s Sparrow
The most serious threat to this site is recreational and residential development.
Noxious weed invasion has increased along reservoir edge roads. Increased recreational use (e.g., dispersed camping and ATV use) contribute to the invasive plant problem, as well as increasing disturbance to nesting birds. To combat the weed problem, the U.S. Forest Service has initiated noxious weed control. While not a serious habitat threat at this time, grazing along the reservoir edge is a concern, and is being monitored by the Forest Service. An increase in recreational and off road vehicle use around the reservoir and below high water mark during dry periods is a significant threat to habitat security and quality. Some diversions leading into the reservoir have been altered to protect these habitats along the source streams.
Irrigation storage reservoir. Two small creeks, Sheridan Creek and Icehouse Creek enter the reservoir on the west end. Surrounding habitat varies from coniferous forest (doug-fir/lodgepole/aspen) to shrub-steppe. Draw down during summer exposes extensive mudflats.
Island Park Reservoir is a very popular fishing and recreational site. Wildlife watching opportunities are abundant but under-exploited.