Two federally listed fishes, the Foskett speckled dace and Warner sucker, are endemic to Warner Basin in south central Oregon. The Foskett speckled dace is native only to a single spring in Coleman Valley. A nearby spring was stocked with dace in 1979 and 1980, and now provides a second population. The present numbers of dace probably are at their highest levels since settlement of the region. The Warner sucker historically occurred throughout much of the Warner Valley, but its distribution and abundance have been reduced by construction of reservoirs and irrigation dams and the introduction of predatory game fishes. Lentic habitats have become dominated by introduced fishes, particularly white crappie, black crappie, and brown bullhead. The largest remaining population of Warner suckers occurs in Hart Lake, where successful reproduction was documented but there is no evidence of recruitment to the adult population.
Williams, Jack E.; Stern, Mark A.; Munhall, Alan V.; and Anderson, Gary A.
"Conservation status of threatened fishes in Warner Basin, Oregon,"
Great Basin Naturalist: Vol. 50
, Article 5.
Available at: https://scholarsarchive.byu.edu/gbn/vol50/iss3/5