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Transport reaches (3 to 30 percent gradient) dominate the perennial stream networks, with inclusions ofresponse reaches (less than 3% gradient). Field observations in North Fork Pistol and upper Hunter Creekhave found these characterizations to be accurate. Hunter Creek has large inner gorge landslides in theperidotite canyon; North Fork Pistol has localized areas of inner gorge instability.In the project area, the locations of all intermittent streams, and the few perennial streams adjacent toproposed treatment units, were located and mapped with GPS equipment (Figure 1). Channelcharacteristics were noted during this process. Larger streams downstream of the project area were spotchecked; the watershed analyses incorporated stream survey data on fish-bearing reaches.The geomorphology of the area has irregular slopes, in both steepness and aspect. Intermittent streamchannels characteristically form in steeper areas, disperse and disappear in flatter topography, then formagain as slopes increase. Where channels are well-developed, they tend to be downcutting in deep soilsand shallow in rocky areas. The inner gorges that slope down to the stream banks appear stable and wellvegetated.Riparian ReservesReference ConditionsRiver valley morphology for nearly all channel segments in the Pistol River and Hunter Creek watershedsis classified as confined. This confinement limited floodplain development. Consequently, riparianspecies (willows, sedges etc.) that depend on fine fluvial sediment deposits for establishment were fewand limited to the stream margins. Based on 1940 aerial photographs and field visits to undisturbedriparian zones in the North Fork Pistol and Hunter Creek, riparian zones on perennial streams weredominated by conifer species which provided a full canopy. Many of these stands had an understorycomponent of hardwood species. Due to a dominant component of conifers and a full canopy reducingsolar radiation input, streamside shade and large woody debris (LWD) recruitment potential were high.The inner gorge area along the mainstem of Hunter Creek, near Pine Point, had a reduced conifer andvegetative component. Low productivity soil of peridotites along the inner gorge of Hunter Creeksupported a minimal canopy cover (less than 30 percent) with an open understory. One reach of the innergorge is void of vegetation due to constant erosion.Management HistoryHarvest on National Forest land in the watersheds began in 1955. During the late 1950s and early 1960sharvest practices included clearcutting riparian areas. During the period from 1980 to 1989, narrowriparian buffers on perennial streams were usually left uncut or partially cut, but harvest practicesincluded stream cleanout, removing large wood from channels. The Northwest Forest Plan of 1994implemented Standards and Guidelines for Riparian Reserves, but no regeneration harvest has taken placeon National Forest land in these watersheds since then.Perennial StreamsPerennial streams and adjacent riparian areas are generally the most biologically diverse locations in thewatershed. Terrestrial species utilize the dense riparian vegetation as a travel and dispersal corridor. Thegrasses, shrubs, and hardwoods within the riparian zone provide an important food source for bothterrestrial and aquatic species. Due to relatively high moisture content and a multiple canopy ofhardwoods and conifers, these riparian areas provide thermal refuge in times of heat and drought. Thestreamside vegetation also provides a microclimate for riparian dependent species such as salamandersand frogs.Supplementary Analysis ReportPyramid Thin ProjectHydrology ReportPage 5

Perennial streams in the three sixth field watersheds lie outside the proposed treatment areas. The fewperennial streams in the vicinity of treatment areas are small and fed by ridgetop springs and seeps. Theriparian microsites associated with them tend to be narrow, some with dense undergrowth such as salal,and others with azalea and darlingtonia.Intermittent StreamsThe NWFP ROD defines intermittent channels as any nonpermanent flowing drainage feature having adefinable channel and evidence of annual scour or deposition. Intermittent channels often provide moistmicroclimates for amphibian species seeking shelter and nest sites, and for terrestrial species seekingthermal refuge and travel corridors. Intermittent channels also act as a conveyance system, deliveringsediment and nutrients to perennial fish bearing streams. Riparian zones play a major role in regulatingnutrient and energy flow in low-order streams.Streams in the vicinity of the proposed treatment areas usually begin as small, spatially intermittentephemeral channels. As they continue downhill they often vary in depth, first eroding a channel an inchor two in depth, then disappearing with no evidence of scour or deposition, then eroding a channel up toseveral feet deep, then dispersing over a flat area and disappearing again, before forming a continuouschannel.Vegetation adjacent to most segments of intermittent channels, as well as further out in their RiparianReserves, is indistinguishable from the upslope vegetation: Douglas fir, Jeffrey pine, knobcone pine,incense cedar, Port-Orford-cedar, hardwoods including tanoak, madrone, and canyon live oak, withscattered salal and swordfern. In summer and fall when channels are dry, banks and bottoms are also dry,with no cool or moist microsites. Rarely, a short stretch of intermittent stream channel is discovered withdamp banks, green grasses, or small puddles. Where these microsite locations are found, the cooler,moister conditions do not extend beyond the stream banks up into the inner gorge. These dry conditionslimit the extent to which intermittent streams around the treatment areas contribute to the processesdescribed above.Meadows are scattered throughout the general area. Intermittently flowing channels in these meadowsprovide nutrient diversity to the streams in this otherwise forested landscape.Hyporheic Areas and WetlandsBedrock and hillslope confinement limit the extent of hyporheic areas in most of the terrain in and aroundproposed treatment areas. However, irregular topography and ultramafic soils have created severalwetlands. Along the ridge separating Pistol from Hunter are several pond-like seasonally wet areascovered with azalea. Further down the slope in the North Fork Pistol, small poorly-defined intermittentstreams flow through flat, open meadowy areas. Rushes and willows indicate seasonally wet portions ofsome of these meadows. Where well-defined intermittent streams flow across flat areas, there areoccasional side channels, floodplains, well-developed riparian microsites, and opportunities for hyporheicflow.Canopy CoverThe Pistol River WA identified 38 percent mature and old-growth forest, 23 percent “young” and 38percent seed-sapling-pole sized trees within the North Fork Pistol Riparian Reserves (perennial streamsonly). In the vicinity of the Pyramid Thin proposed treatment areas, approximately 10 percent of the 515acres of intermittent stream Riparian Reserves (both Pistol and Hunter watersheds) are in previouslyharvested areas. The remaining 90 percent is primarily young to mature conifers, with open and sparselyvegetated serpentine areas.Supplementary Analysis ReportPyramid Thin ProjectHydrology ReportPage 6

The Hunter Creek Watershed Analysis found that the biggest concern within the riparian zone is the lackof large tree structure. The existing large tree structure does not, and is not expected to for the next 50years, provide adequate large wood recruitment into the channel environment. Lack of large treestructure has also reduced habitat connectivity and species diversity.Large Wood RecruitmentThe upper Hunter Creek channel is lacking large wood, probably because of prior timber harvest andchannel cleanout practices. Additionally, past riparian harvest has reduced the potential for large woodrecruitment. This reduction in large wood has removed the structure that would characteristically createpool-riffle morphology in channels with these gradients. The channel is left with a uniform gradient andlong, nearly continuous riffles. Downstream of the harvested area is the peridotite canyon, with rockyultramafic soils that support very little vegetation.In the North Fork Pistol, the steepness of the inner gorge made harvest of the trees immediately adjacentto the stream banks difficult. Although the strip of large trees is less than one site potential tree height inwidth in many areas, the quantity of future large wood has been only moderately diminished.Sediment Delivery ProcessesThe Pistol River WA and Hunter Creek WA identify mass movement as the primary source of sedimentdelivery to streams prior to management activities; with minor contributions from surface erosion andravel, primarily on ultramafic soils or after catastrophic fires. Pyramid Thin Project proposed treatmentareas lie over geologic formations where natural landslide activity tends to be small slides typicallyconcentrated in inner gorges and stream adjacent sideslopes and drainage headwalls (Refer to the Geologyand Soils Report for more details).Effects of prior management activitiesIncreases in mass failures following timber harvest and road construction were documented in the PistolRiver Study (Russell 1994, cited in Evans and Associates 2003). Early tractor harvest may have added tothe surface erosion. Contributions to sediment delivery have decreased following changes in forestpractices in the 1980s and 1990s. Surface erosion from road cuts and fillslopes continues to occur, as doroad related failures, but these are minor contributors to the sediment regime.Water QualitySeveral streams in the 6th field watersheds associated with the Pyramid Thin Project treatment areas andassociated actions are considered water quality limited by the Oregon Department of EnvironmentalQuality (ODEQ) and are on the 303(d) list in the 2004/2006 Integrated Report. Table 2 identifies thestreams that are listed as Category 5 water quality limited, the parameters for which they are listed, andthe beneficial uses that are protected by the pollutant standard.Supplementary Analysis ReportPyramid Thin ProjectHydrology ReportPage 7

Table 2. Water Quality Limited Streams. Includes streams within the North Fork Pistol River, UpperHunter Creek, and Lower Hunter Creek 6th field watersheds.Stream /ParameterSeasonBeneficial UsesRiver MileHunter Creek

The Pyramid Thin Project treatment areas are located within two 5th field and three 6th field watersheds in the Chetco River Sub-basin (Table 1). Watershed boundaries and acreages in this report are based upon the most up-to-date U.S. Geological