Generalized fish distribution is "areas of suitable habitat currently believed to be used by wild, hatchery, or naturalized fish populations, based on sampling and/or best biological judgment." ("Current" is defined by each data-providing agency according to their own policies.) This table is for where species are found, but does not address where species are not found -- lack of a record does not imply that the species does not exist in a given reach. More technical information is available for this data category's database structure.