OAR 635-412-0005


For the purposes of OAR 635-412-0010 (Fish Passage Task Force) through 635-412-0040 (Mitigation Criteria) the following definitions shall apply.


“Active channel width” means the stream width between the ordinary high water lines, or at the channel bankfull elevation if the ordinary high water lines are indeterminate.


“Artificial obstruction” means any dam, diversion, dike, berm, levee, tide or flood gate, road, culvert or other human-made device placed in the waters of this state that precludes or prevents the migration of native migratory fish.


“Attraction flow” means the flow that emanates from or near a fishway entrance in sufficient quantity, velocity, and location to attract upstream migrants into the fishway, which can consist of gravity flow from the fish ladder and auxiliary water system flow added in or near the lower ladder.


“Bankfull elevation” means the point on a stream bank at which overflow into a floodplain begins.


“Bed” or “bed and banks” means the physical container of the waters of this state, bounded on freshwater bodies by the ordinary high water line or bankfull stage, and on bays and estuaries by the limits of the highest measured tide.


“Channel” means a waterway that periodically or continuously contains moving waters of this state and has a definite bed and banks that serve to confine the water.


“Commission” means the Oregon Fish and Wildlife Commission.


“Construction” means:


Original construction;


Major replacement, which includes:


for dams and diversions, excavation or replacement of 30 percent by structure volume of the dam, including periodic or seasonal replacements, unless:
Only checkboards are replaced; or
Fish passage approval has already been obtained in writing from the Department for expected replacement.


For tide gates and flood gates:
Cumulative replacement of over 50 percent of the gate material; or
Cumulative removal, fill, replacement, or addition of over 50 percent of the structure supporting the gate, excluding road-stream crossing structures.


For dikes, berms, levees, roads, or other artificial obstructions that segment estuaries, floodplains, or wetlands:
Activities defined under OAR 635-412-0005 (Definitions)(9)(d) in all locations where current channels cross the artificial obstruction segmenting the estuary, floodplain, or wetland; or
The cumulative removal, fill, replacement, or addition of over 50 percent by volume of the existing material directly above an historic channel or historically-inundated area; and


For other artificial obstructions, the cumulative removal, fill, replacement, or addition of over 50 percent of the structure comprising the artificial obstruction to native migratory fish migration;


Structural modifications that increase storage or diversion capacity; or


For purposes of culverts, installation or replacement of a roadbed or culvert, further defined as:


Roadbed installation or replacement at culverts includes any activity that:
Creates a road which crosses a channel;
Widens a roadfill footprint within a channel; or
Fills or removes over 50 percent by volume of the existing roadbed material directly above a culvert, except when this volume is exclusively composed of the top 1 foot of roadbed material.


Culvert installation or replacement includes any activity that:
Installs or constructs a new culvert, overflow pipe, apron, or wingwall within a channel;
Extends existing culverts, aprons, or wingwalls within a channel, except one-time placements of culvert ends which do not extend greater than 1 foot beyond the adjacent road footprint in place prior to August 2001;
Cumulatively through time makes significant repairs or patches to over 50 percent of the linear length of a culvert;
Replaces any part of a culvert, except ends which become misaligned or eroded and which are replaced to their original configuration;
At any point along the linear length of a culvert, reduces the entire inside perimeter of the culvert; or
Makes replacements, repairs, patches, or modifications to an existing culvert that are different than the original configuration and which reduce any level of fish passage for native migratory fish with current access, as determined by the Department, to the culvert.


“Dam” means a structure, or group of structures with different functions, spanning or partially-spanning a stream in one location in order to pool water, facilitate the diversion of water, or raise the water surface elevation.


“Department” means the Oregon Department of Fish and Wildlife.


“Director” means the Director of the Oregon Department of Fish and Wildlife.


“Design streamflow range” means the range of flows within a stream, bracketed by the Low Fish Passage Design Flow and the High Fish Passage Design Flow, for which a fishway shall provide fish passage.


“Emergency” means unforeseen circumstances materially related to or affected by an artificial obstruction that, because of adverse impacts to a population of native migratory fish, requires immediate action.


“Estuary” means a body of water semi-enclosed by land and connected with the open ocean within which salt water is usually diluted by fresh water derived from the land. “Estuary” includes all estuarine waters, tidelands, tidal marshes and submerged lands extending upstream to the head of tidewater. However, for the purposes of these rules, the Columbia River Estuary extends to the western edge of Puget Island.


“Exclusion barrier” means a structure placed that prevents fish passage for the benefit of native migratory fish.


“Experimental fish passage structure" means a fish passage structure based on new ideas, new technology, or unique, site-specific conditions determined by the Department to not be covered by existing fish passage criteria but to have a reasonable possibility of providing fish passage.


“Fish passage” means the ability, by the weakest native migratory fish and life history stages determined by the Department to require passage at the site, to move volitionally, with minimal stress, and without physical or physiological injury upstream and downstream of an artificial obstruction.


“Fish passage structure” means any human-built structure that allows fish passage past an artificial obstruction, including, but not limited to, fishways and road-stream crossing structures such as culverts and bridges.


“Fishway” means the set of human-built and/or operated facilities, structures, devices, and measures that together constitute, are critical to the success of, and were created for the sole purpose of providing upstream fish passage at artificial or natural obstructions which create a discontinuity between upstream and downstream water or bed surface elevations.


“Fishway entrance” means the component of a fishway that discharges attraction flow into the tailrace and where upstream migrant fish enter the fishway.


“Fishway pools” means discrete sections within a fishway separated by overflow weirs or non-overflow walls that create incremental water surface elevation gains and dissipate energy.


“Floodplain” means that portion of a river valley, adjacent to the channel, which is built of sediments deposited during the present regimen of the stream and which is covered with water when the waterway overflows its banks at flood stage.


“Forebay” means the water impounded immediately upstream of an artificial obstruction.


“Fundamental change in permit status” means a change in regulatory approval for the operation of an artificial obstruction where the regulatory agency has discretion to impose additional conditions on the applicant, including but not limited to licensing, relicensing, reauthorization or the granting of new water rights, but not including water right transfers or routine maintenance permits unless they involve construction or abandonment of an artificial obstruction.


“High fish passage design flow” means the mean daily average stream discharge that is exceeded 5 percent of the time during the period when the Department determines that native migratory fish require fish passage.


“Historically” means prior to 1859 (statehood).


“Inflow” means surface movement of waters of this state from a lower ground surface elevation to a higher ground surface elevation or away from the ocean.


“In-proximity” means within the same watershed or water basin, as defined by the Oregon Water Resources Department, and having the highest likelihood of benefiting the native migratory fish populations, as defined by the Oregon Department of Fish and Wildlife, directly affected by an artificial obstruction.


“Low fish passage design flow” means the mean daily average stream discharge that is exceeded 95 percent of the time, excluding days with no flow, during the period when the Department determines that native migratory fish require fish passage.


“Mitigation” means alternatives to providing fish passage at an artificial obstruction as per ORS 509.585 (Fish passage required for artificial obstructions).


“Native migratory fish” means native fish (as defined under OAR 635-007-0501 (Definitions)) that migrate for their life cycle needs. These fish include all sub-species and life history patterns of the following species listed by scientific name in use as of 2005. Common names are provided for reference but are not intended to be a complete listing of common names, sub-species, or life history patterns for each species.


Acipenser medirostris — Green Sturgeon;


Acipenser transmontanus — White Sturgeon;


Amphistichus rhodoterus — Redtail surfperch;


Catostomus columbianus — Bridgelip sucker;


Catostomus luxatus/Deltistes luxatus — Lost River sucker;


Catostomus macrocheilus — Largescale sucker;


Catostomus microps — Modoc sucker;


Catostomus occidentalis — Goose Lake sucker;


Catostomus platyrhynchus — Mountain sucker;


Catostomus rimiculus — Klamath smallscale sucker;


Catostomus snyderi — Klamath largescale sucker;


Catostomus tahoensis — Tahoe sucker;


Catostomus warnerensis — Warner sucker;


Chasmistes brevirostris — Shortnose sucker;


Hypomesus pretiosus — Surf smelt;


Lampetra ayresi — River lamprey;


Lampetra lethophaga — Pit-Klamath lamprey;


Lampetra minima — Miller Lake lamprey;


Lampetra similes — Klamath River lamprey;


Lampetra tridentate — Pacific lamprey;


Oncorhynchus clarki — Coastal, Lahontan and West Slope cutthroat trout;
Oncorhynchus keta — Chum salmon;


Oncorhynchus kisutch — Coho salmon;
Oncorhynchus mykiss — Steelhead, Rainbow and Redband trout;


Oncorhynchus nerka — Sockeye/Kokanee salmon;


Oncorhynchus tshawytscha — Chinook salmon;


Prosopium williamsoni — Mountain whitefish;


Ptychocheilus oregonensis — Northern pikeminnow;


Ptychocheilus umpquae — Umpqua pikeminnow;


Salvelinus confluentus — Bull trout;


Spirinchus thaleichthys — Longfin smelt;


Thaleichthys pacificus — Eulachon.


“Net benefit” means an increase in the overall, in-proximity habitat quality or quantity that is biologically likely to lead to an increased number of native migratory fish after a development action and any subsequent mitigation measures have been completed.


“Ordinary high water line” (OHWL) means the line on the bank or shore to which the high water ordinarily rises annually in season.
NOTE: See OAR 141-085-0010 for physical characteristics that can be used to determine the OHWL in the field.


“Oregon Plan” means the guidance statement and framework described in ORS 541.405.


“Over-crowding” means fish density within a pool’s wetted volume is such that there is less than 0.25 cubic feet of water per pound of fish for the maximum number of fish expected to be present within the pool at the same time, as determined by the Department.


“Road” means a cleared or built surface, and associated materials or measures for support and safety, used for the purpose of motorized or non-motorized movement between different locations.


“Roadfill footprint” means the area occupied by soil, aggregate, and/or other materials or structures necessary to support a road, including, but not limited to, appurtenant features such as wing walls, retaining walls, or headwalls.


“Stream” means a body of running waters of this state moving over the surface of the land in a channel or bed including stream types classified as perennial or intermittent and channelized or relocated streams.


“Sub-basin” means a 4th-field hydrologic unit as defined by the U.S. Geological Survey.


“Tailrace” means the water immediately downstream of an instream structure.


“Temporary” means in place less than the in-water work period defined by the Department for a particular location.


“Trap” means the set of human-built and/or operated facilities, structures, devices, and measures that hold fish and prevent them from passing volitionally.


“Unforeseen circumstances” means:


An event that causes an existing human-made structure in the waters of the state which provides fish passage to become an artificial obstruction; or


New fish population information indicating that an existing artificial obstruction is placing a local native migratory fish population in jeopardy.


“Volitionally” means with minimal delay and without being trapped, transferred, or handled by any person, unless specifically allowed under OAR 635-412-0035 (Fish Passage Criteria)(6).


“Waters of this state” means natural waterways including all tidal and non-tidal bays, intermittent and perennial streams, constantly flowing streams, lakes, wetlands and other bodies of water in this state, navigable and non-navigable, including that portion of the Pacific Ocean that is within the boundaries of Oregon.


“Wetlands” means those areas that are inundated or saturated by surface or ground water at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions.
Last Updated

Jun. 8, 2021

Rule 635-412-0005’s source at or​.us