The Miller Lake Lamprey was believed extinct after a chemical treatment in 1958 that targeted lamprey and tui chub. Both species were extirpated from Miller Lake. The lamprey population was later recognized to be a distinct species, Lampetra minima (Bond and Kan 1973). It was the smallest lamprey species in the world (maturing at less than 4 in), and at that time was known only from Miller Lake, where it was extinct. In 1992, a small lamprey captured in the Upper Williamson River was identified as a Miller Lake Lamprey, and subsequent investigations have identified six local populations of this lamprey in two small subdrainages of the Upper Klamath Basin, the upper Williamson River and the upper Sycan River above Sycan Marsh. The upper Williamson River contains four known populations (Miller Creek, Jack Creek, Klamath Marsh, and mainstem Williamson River above the marsh). Miller Creek, which drains Miller Lake, is within the upper Williamson Watershed, but it goes sub-surface in the pumice soils and does not reach the Klamath Marsh or Williamson River. Jack Creek, a small northern tributary to the upper Williamson River, is also generally disjunct from the mainstem Williamson River due to low, intermittent surface flows in its lower reaches. The Upper Sycan drainage contains two principal populations, Long Creek drainage and the upper Sycan River drainage above Sycan Marsh. Lamprey are also assumed present in the Sycan Marsh itself.

Miller Lake Lamprey feed on fish only as adults. Ammocoetes have no eyes or teeth and are purely filter feeders, burrowing in the sediment and feeding on suspended microorganisms and algae. The ammocoete phase lasts about five years, during which time the ammocoetes grow to around 150 mm. After transformation, adults enter a predatory phase that generally lasts for less than a year.  Adults feed primarily on flesh that is gouged and rasped out of a small wound under the sucking disk.   Adults apparently show little selectivity for prey. The adult lampreys in Miller Lake historically fed on both tui chubs and available salmonids in Miller Lake.

Following the extirpation of lampreys from Miller Lake in 1958, a lamprey barrier was constructed in Miller Creek to prevent recolonization of the lake from Miller Creek. The barrier was constructed by the State of Oregon Game Commission in 1959 at the upstream extent of a short, high-gradient cascade in Miller Creek approximately ½ mile downstream from the outlet of Miller Lake.  In efforts to conserve the Miller Creek population and to allow recolonization of the lake, the barrier was removed in 2005.

Recent baseline surveys (August 2004) of lamprey ammocoetes in the Miller drainage indicate that they are apparently limited to less than two miles of low-gradient stream in lower Miller Creek. Allowing lampreys to re-establish a population above the cascade in Miller Creek and Miller Lake will aid in creating an additional buffer against stochastic events that could otherwise eradicate this geographically limited population. Since the removal of the barrier efforts are being taken to monitor the population and its distribution.  In the summer of 2006 biologists from the Native Fish Investigations Project, ODFW, USFS, and Western Fishes electrofished Miller Creek above and below the barrier site to detect the presence of Miller Lake Lamprey and possibly indicate recolonization.  No lamprey were detected.

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