Interim Guidance Fish Presence Absence

Transcription

1 Interim Guidance Fish Presence Absence Source: Forest Practices Act Guidance for Division 635 of the forest practices act dealing with stream classification when no fish surveys have been done (referenced below). WATER CLASSIFICATION OAR (11) (b) (B) The department will approximate the upstream extent of fish use in a watershed by considering the connection of the water with downstream waters where fish use is known. Fish use will be assumed to occur upstream of the known fish use until the first natural barrier to fish use is encountered. The intent of this paragraph is to allow the department to classify fish use for streams with unknown fish use in the interim (until a physical survey for fish presence/absence is conducted). The "approximation" process can be applied when a notification is received or prior to receiving a notification on a broader mapping scale so long as the proper process is applied. In applying the approximation process, it was the intent of this paragraph to assume fish use in streams that have connection with a stream with known fish use (any stream that was previously classified as Class I and any stream where a survey has confirmed fish presence) up to the first natural barrier. A natural barrier is defined by OAR (39) as: "Natural barrier to fish use" is a natural feature such as a waterfall, increase in stream gradient, channel constriction, or other natural channel blockage that prevents upstream fish passage. Applying "upstream of the known fish use until the first natural barrier to fish use is encountered" will result in not classifying some fish use that can occur above a natural barrier to fish use. However, the intent was to provide an equitable process that could be applied on short timelines until the comprehensive survey is done. The conservative results of the interim process will help ensure that landowners will not be required to apply Type F protection on streams that in reality do not have fish use. In addition, this approach was also intended to maintain incentives to complete the comprehensive survey for actual fish use. More accurate classification will result when the comprehensive fish use survey is completed. Even when fish use has been surveyed, and fish use has been verified up to a man-made barrier, the following policies apply. When a crossing structure that creates an upstream Type N stream segment is replaced, it is required to provide fish passage. When this allows fish to occupy the upstream segment, the classification will be changed from Type N to Type F. [REVISED this paragraph added.] The most important consideration in applying the interim process is that Forest Practices Foresters are not experts about barriers to fish passage. The department has final authority to make decisions about barriers. Apply your best judgment based upon the Rev. 7/31/2007 Page 1 of 6

2 information available to you about barriers, but recognize that this is an interim process. Fish use will be assumed up to the first natural barrier. Natural barriers include waterfalls or other natural channel features. Natural barriers do not include beaver dams, log jams, or woody debris piles. Such "organic" obstructions are temporary and in most cases do not block fish. Culverts do not count as natural barriers unless located at a natural barrier. A falls, chute, channel gradient change, or lack of livable space should be considered a barrier if it is more likely that fish could not pass above the channel feature than pass the feature. The rule very clearly states we assume fish use only up to the first barrier. In order of priority, a barrier to fish use can be determined two ways. First, the stream channel from its confluence with fish use waters can be physically surveyed up to the first natural barrier. This approach can be applied if an actual fish presence survey cannot be conducted due to timing issues; that is, fish may be there at other times of the year, but due to such factors as seasonality of flow, they are not likely to be there at the time the survey must be conducted. Generally, the stream channel should be observed for falls, chutes, and steep channel sections that are likely to prevent upstream fish passage. A map can be examined to prioritize sections of stream to observe in the field for barriers. If barriers are found above confirmed fish use, fish use should be assumed to end there unless fish are observed above the barrier. The second method is to determine barriers to fish use based upon a map analysis. This method may be applied on a broad scale (in a manner unrelated to receipt of a notification) or on an operation-specific basis. One advantage of the broader scale approach is that landowners and other interested parties will be able to know ahead of time where we will assume fish use if a fish presence or channel survey is not conducted. Therefore, districts are encouraged on a broad scale to map assumed fish on the district maps following the guidance in the mapping section. The map method is to be applied in the context of "barriers" and not in the context of "the probability of fish use". That is, the channel should be analyzed on the map from its confluence with known fish use to find the first channel feature on the map that is likely to block fish passage. The notion of probability of fish use can be used in selecting the methodology to determine fish use; that is, whether to do a fish survey, a channel survey, or use the map process. However, if physical fish presence surveys cannot be conducted, the only criterion for determining the upstream extent of fish use is the location of the first natural barrier to fish use. The following criteria are established to define natural barriers that are more likely to not pass fish than to pass fish for either field and/or map application. In applying the criteria, if there are no known waterfalls or chutes, then channel gradient and physical habitat (lack of livable space due to no pools or inadequate water volume) should be considered in determining barriers. Rev. 7/31/2007 Page 2 of 6

3 In applying these factors, we should again be assuming a barrier when it is more likely that fish cannot move through a steep channel segment or that the lack of livable space is a barrier. When evaluating a potential barrier, the expected flows during high spring or winter flows should be considered. Conditions for fish passage at a site during low summer flow can be very different from what occurs during high flows. For example, a falls that appears five feet high during low summer flows may be less than three feet high during higher flows. Stream levels based upon bankfull width should be used as points of reference in measuring channel drops. Barriers to fish use: a. Falls - physical survey For salmon and steelhead streams, any falls or steep bedrock chute with eight feet or greater vertical drop is a barrier. For resident trout streams, any falls or steep bedrock chute with four feet or greater vertical drop is a barrier. Any falls or steep bedrock chute with less than a two-foot vertical drop is not a barrier. For falls or steep chutes with vertical drops between those described above, if the falls or chute is without a jump pool or the jump pool depth (estimated to be there during high flow periods) is less than 1.25 times the height of the falls or chute, a barrier exists. For example, a fish can jump a two-foot vertical falls if there is a pool 2.5 feet deep at the bottom of the falls, and the falls would not be considered a barrier in this case. b. Falls - map survey Any waterfall marked on a map should be considered a barrier. c. Channel Steepness - physical survey Any channel segment (30 feet or longer on salmon/steelhead streams and 20 feet or longer for resident trout streams) with a gradient that exceeds 20 percent is a barrier. Any channel segment (using same length segments as above) with a gradient that exceeds 12 percent should be considered a barrier if the channel is bedrock without pools or low velocity areas, or otherwise does not have pools. This can vary between 12 and 20 percent depending upon channel form (frequency of step pools versus bedrock channel without pools). One advantage of the physical channel survey is that judgment and local experience can be applied in determining whether or not channel steepness is reasonably likely to prevent fish Rev. 7/31/2007 Page 3 of 6

4 passage. In the map approach, decisions will be based solely upon gradient and not channel form. d. Channel steepness - map survey Any channel segment with a gradient that exceeds 20 percent is a barrier to fish use. Not all steep channel segments will be apparent on a map. Local knowledge should be applied in appropriate situations. For example, if side streams to a main stream with fish characteristically drop steeply to the main stream and these drops have been found to be barriers to fish use even though they may not show on a map, this information should be used to establish a barrier. However, in this situation it is recommended that the expected drop be confirmed by a field visit. e. Lack of livable space - physical survey A channel has inadequate livable space to pass fish if it does not contain pools that are approximately a foot or more in depth during spring spawning season or other periods of high flow when fish would normally be expected. During low water periods the channel can be observed for indications that such pools exist during higher spring flows. f. Lack of livable space - map survey Coast Range Geographic Region: Basins with a drainage area of 60 acres or less are barriers to fish. South Coast Geographic Region: Basins with a drainage area of 80 acres or less are barriers to fish. Interior, and West Cascade Geographic Regions: Basins with a drainage area of 100 acres or less are barriers to fish. Siskiyou Geographic Region: Basins with a drainage area of 300 acres or less are barriers to fish. Blue Mountain and East Cascade Geographic Regions: Basins with a drainage area of 350 acres or less are barriers to fish. Streams with known perennial stream flow in these geographic regions, regardless of basin size, should be a high priority for fish surveys. The criteria related to lack of livable space were developed using limited fish presence survey data. These criteria should be used until additional fish presence survey data are locally available. However, as such data are developed locally, districts in coordination with local ODFW biologists may adjust these criteria. Such adjustments must be Rev. 7/31/2007 Page 4 of 6

5 supported by local data and be consistent with the policies in this guidance related to fish presence. For example, if SWO District and the ODFW district fish biologist agree that actual fish presence data indicates that basins of 400 acres are more likely to prevent fish passage than allow fish passage in areas of the district with less than 20 inches of rainfall, then that criteria may be used in place of the criteria in this guidance. Rev. 7/31/2007 Page 5 of 6

6 Table 1: Summary Of Interim Process For Determining Approximate Upstream Extent of Fish Use Type of Barrier Physical Survey Map Analysis Falls & Chutes Channel Steepness With Pools W/O Pools Lack of Livable Space Salmon & Steelhead 8'+ Resident Trout 4'+ 2'+ require a jump pool 1.25 times the fall or chute height. 30' or 20%+ 30' or 12%+ Any waterfall marked on a map. 20' or 20%+ 20%+ 20' or 12%+ No pools approximately 12" or more in depth during spring spawning. 60 Acres or Less (Coast 80 Acres or Less (South Coast) 100 Acres or Less (Interior) 300 Acres or Less (Siskiyou) 350 Acres or Less (Blue Mountain and East Cascade) Rev. 7/31/2007 Page 6 of 6