The Foskett Spring speckled dace Rhinichthys osculus ssp. is represented by a single population that inhabits Foskett Spring on the west side of Coleman Lake in Lake County, Oregon. This species was listed as threatened under the federal Endangered Species Act in 1985. In 2005, the Native Fish Investigations Project initiated Foskett speckled dace investigations to monitor 1) population abundance, 2) age composition, and 3) habitat conditions.

Speckled dace are geographically widespread throughout the western United States and occur in many isolated subbasins and interior drainages in south-central Oregon. The Foskett speckled dace became isolated in Foskett Spring at the end of the pluvial period approximately 10,000 years ago. Foskett Spring is a natural spring that rises from a springhead pool, flows through a narrow springbrook into a series of shallow marshes, and then disappears into the soil of the normally dry Coleman Lake. A second population of Foskett dace was established in Dace Spring located approximately 0.8 kilometer south of Foskett Spring, from an introduction of 100 fish from Foskett Spring in 1979-1980; however recent surveys have failed to document their continued existence at this location.  In 1987, the U.S. Bureau of Land Management (BLM) acquired, through exchange, the 65 hectare parcel of land containing Foskett and Dace Springs. Both sites were fenced to exclude livestock.

The Recovery Plan for the Threatened and Rare Native Fishes of the Warner Basin and Alkali Subbasin states that this species will probably not be delisted in the near future because of its extremely isolated range and potential for degradation of its habitat from localized events. The primary recovery objective for this species is the long-term persistence through preservation of its native ecosystem.  The plan further states that the conservation and long term sustainability of this species will be met when: 1) long-term protection to its habitat, including spring source aquifers, springpools and outflow channels, and surrounding lands is assured; 2) long-term habitat management guidelines are developed and implemented to ensure the continued persistence of important habitat features and guidelines include monitoring of current habitat and investigation for and evaluation of new spring habitats; and 3) research into life-history, genetics, population trends, habitat use and preference, and other important parameters is conducted to assist in further developing or refining criteria 1) and 2), above. Actions needed to meet these criteria include protecting and rehabilitating fish populations and habitats, conserving genetic diversity of fish populations, ensuring adequate water supplies are available for recovery, monitoring population and habitat conditions, and evaluating long-term effects of climatic trends on recovery.