We, NOAA Fisheries, announce a 90-day finding on a petition to list as threatened or endangered the Upper Klamath-Trinity Rivers (UKTR) Chinook salmon Evolutionarily Significant Unit (ESU) (Oncorhynchus tshawytscha) or, alternatively, create a new ESU to describe Klamath Spring Chinook salmon and list the new ESU as threatened or endangered under the Endangered Species Act (ESA). The petition also requests that we designate critical habitat concurrently with the listing. We find that the petition presents substantial scientific information indicating the petitioned actions may be warranted. We will conduct a status review of the Chinook salmon in the UKTR Basin to determine if the petitioned actions are warranted. To ensure that the status review is comprehensive, we are soliciting scientific and commercial information pertaining to this species from any interested party.