AQUATIC ECOSYSTEM RESTORATION PROJECT

Transcription

1 AQUATIC ECOSYSTEM RESTORATION PROJECT EFFECTS OF THE FLOODS OF 1996 QUARTZ CREEK WILLAMETTE NATIONAL FOREST Submitted by: Dr. Stan Gregory Randy Wildman Department of Fisheries and Wildlife Oregon State University Corvallis, Oregon December, 1998

2 TABLE OF CONTENTS I. Introduction...1 II. Review of the two flood events of Overview of Quartz Creek restoration project...4 III. Project site description...6 IV. Methods...8 V. Results Characteristics prior to project installation Project installation Installation of wood accumulations Responses after project installation Behavior of large wood accumulations Retention of water and particulate material Change in channel morphology Changes in trout populations VI. Discussion Performance of log structures Evaluation of log accumulations Ecological responses VII. Summary VIII. Suggestions IX. Literature Cited... 75

3 INTRODUCTION Quartz Creek is a major tributary on the south side of the McKenzie River in the western Cascades of Oregon and potentially supports populations of coastal cutthroat trout (Oncorhynchus clarki), rainbow trout (O. mykiss), chinook salmon (O. tshawytscha), and bull trout (Salvelinus confluentus). Past forest practices and possibly natural events have resulted in an almost total loss of wood from the Quartz Creek channel. The upper portion of the watershed is National Forest System land and the lower portion is private industrial forest. The U.S. Forest Service began restoration of the existing habitat on public land in 1988 by placing large wood accumulations back into the stream. From , the Department of Fisheries and Wildlife at Oregon State University conducted an inventory of physical habitat and fish populations to assist the U.S. Forest Service in developing appropriate wood accumulations to correct habitat deficiencies. Summer of 1993 marked the end of a five-year study period after ecological restoration of the stream and a report entitled Aquatic Ecosystem Restoration Project - Quartz Creek Five-Year Report was produced. OSU personnel conducted an abbreviated survey for wood recruitment of the Quartz Creek restoration site in 1994 and It was agreed upon that OSU would conduct detailed monitoring of the channel and ecological features in the event of a major flood. Two major floods in the 1996 calendar year dramatically altered stream ecosystems and adjacent riparian areas at Quartz Creek and river basins throughout the Pacific Northwest. Extraordinarily high stream flows and associated landslides and flows moved boulders, deposited sediment, and shifted channels along many streams in the McKenzie River basin while other streams in the basin exhibited little change. Evidence from Quartz Creek and the H.J. Andrews Experimental Forest indicates that the two major floods of 1996 behaved differently in basins on the south and north sides of the McKenzie River. The flood that occurred in February resulted in higher stream discharges on the north side of the McKenzie River. The flood in November resulted in higher stream flows on the south side of the McKenzie River. 1

4 DESCRIPTION OF THE TWO FLOOD EVENTS OF 1996 In 1996 the Pacific Northwest experienced not one but two very large storm events. The first flood event started with a series of intense surges of subtropical moisture during the period of February 5 9, Storms of this type from the western Pacific are not rare for Oregon but this storm was unusual in that the surge persisted with strong intensity for 4 days. Record amounts of precipitation were reported at locations in Oregon ( with the maximum occurring at Laurel Mountain in the Coast Range which received 70.8 cm (27.9 in) of rain in the 4- day period (Figure 1). A very large snow pack was present in the Cascade Mountain Range when this storm arrived. As of January 31 the Willamette basin snowpack was 112% of the long-term average for that date. Very warm temperatures accompanied this moist air mass and snow began to melt quickly. Throughout this storm event the freezing level remained at about 2,100 2,400 m (7,000 to 8,000 ft) in elevation. The combination of record-breaking rain, warm temperatures, and the deep snowpack in the Cascade Mountains led to severe flooding. This type of flood event is called a rain-on-snow event and occurs when a subtropical storm drops heavy rainfall onto a previously accumulated snowpack. During the middle of this 4-day storm event streams rose quickly. For example, the McKenzie River rose from 113 m 3 /s (4,000 ft 3 /s) to 566 m 3 /s (20,000 ft 3 /s) in one day at Vida. The McKenzie River reached a peak flow of 730 m 3 /s (25,800 ft 3 /s) at 10:00 P.M. on February 9th. The crest height for the McKenzie River at Vida is 2.7 m (8.8 ft) but this flood brought the flood stage up to 3.4 m (11.0 ft). River flood stages were comparable in magnitude to the December 1964 flood, the largest flood in Oregon since flood control reservoirs were built in the 1940 s and 1950 s. Examination of discharge records from streams at the H.J. Andrews Experimental Forest indicates that the 1996 storm was apparently a larger event than the 1964 flood at low elevations and a smaller event at higher elevations. Peak discharges at small low-elevation basins such as Watershed 1 in the H.J. Andrews Experimental Forest were up to 40% higher in 1996 than the 2

5 Figure 1. Total precipitation for Quartz Creek watershed, Oregon and surrounding states, February 5-9,

6 next highest storm, which occurred in December At small high-elevation basins, peak discharges were as much as 30% lower than the storm of 1964 (Figure 2) ( There is no discharge gauging station on Quartz Creek so exact flood discharge measurements are not available for this stream. A USGS gauging station does exist on Lookout Creek in the H.J. Andrews Experimental Forest, which is approximately 24 km (15 miles) away. Lookout Creek is a fifth-order stream but is somewhat comparable in size to Quartz Creek. Peak flows on Lookout Creek crested at 3.1 m (10.1 ft), which corresponds to a flow of 278 m 3 /s (9,800 ft 3 /s). Peak flows at the same site during the 1964 flood were 189 m 3 /s (6,660 ft 3 /s). Examination of the USGS gage site after the February 1996 flood revealed at least a meter of gravel deposited in the control section for the gage, suggesting that the rating curve may have overestimated the discharge. November brought a second major flood event to Oregon in The Pacific Northwest received record-breaking amounts of rainfall in a short period of time resulting in widespread flooding and numerous landslides. As in the February storm, this storm was created when a broad upper-air weather system of moist subtropical air originating over the tropical Pacific swept into Oregon. Heavy rainfall amounts were reported throughout the state with all-time one-day precipitation records being set at many locations. The City of Corvallis set an all-time one-day record of 10.9 cm (4.28 in) of precipitation. The main difference in this second storm compared to the storms of February 1996 and December 1964 was the reduced snowpack at higher elevations and the precipitation fell as rain onto bare ground in November. Overview of Quartz Creek Restoration Project A brief overview on the background of the Quartz Creek restoration project is presented in this report. For a detailed description of the study, the five-year report should be consulted. This report focuses on the results of monitoring conducted at the Quartz Creek restoration site in

7 and 1997 and the effects of the two major floods on geomorphology, wood, retention, and fish populations at the site. 5

8 Figure 2. Comparison of flood peaks for watershed 1 in the H.J. Andrews Experimental Forest for February 1996 and December

9 The project objective at Quartz Creek was to reestablish natural volumes of large wood to provide complex wood accumulations for salmonid habitat. The increase in wood in Quartz Creek would in turn increase the residence time of water, retention of nutrients, and availability of food resources, which potentially could increase fish populations. The project was designed to introduce and recruit large wood to restore the size classes and volumes that occur in undisturbed streams of similar size and gradient in the McKenzie River drainage. Larger size classes of wood (generally greater than 5 m (16.4 ft) in length and 0.50 m (1.64 ft) in diameter) were placed in the stream to create a matrix of large stable wood that would trap smaller material. This large wood was expected to create the channel structure and wood accumulations found in old-growth forest streams by forming a backbone to retain sediment and smaller wood. PROJECT SITE DESCRIPTION Quartz Creek is a 4th-order stream as defined by Strahler (1957) with a total drainage area of 10,927 ha (27,000 acres). The lower 14.5 km (9 miles) of the stream flow through private forest land (Rosboro Lumber Company) while the upper reaches of the watershed are public lands managed by the U.S. Forest Service. The habitat restoration site was located just upstream from the National Forest boundary approximately 14.5 km (9 miles) from the confluence with the McKenzie River (Figure 3). At the habitat restoration site, Quartz Creek is a 3rd-order stream with a drainage area of 3,440 ha (8,500 acres). Habitat structure was modified within a 1,100-m (3,609-ft) reach of Quartz Creek in Lower and upper sections of the project reach are located in a 400-yr old-growth forest. The middle section of the project site was clearcut down to the stream banks in The reach has an average slope of 4% with a streambed composed predominantly of small and large boulders. Long cascades with channel gradients of more than 8% occur within the study reach. Relatively low amounts of wood were present in the channel due to past disturbances and salvage logging operations. 7

10 Figure 3. Map of Quartz Creek and it s location within the Willamette National Forest. 8

11 METHODS The 1,100-m (3609-ft) reach of Quartz Creek was mapped in detail prior to log introduction. Locations of all existing wood and all boulders over 0.5 m (1.64 ft) in diameter were recorded. Boundaries of geomorphic surfaces (e.g., wetted channel, active channel, and floodplains) were indicated on the maps. Locations of all large trees (by species), snags, wood accumulations, undercut banks, and areas of bedrock outcrops along the stream channel also were recorded. The 1,100 m (3,609 ft) habitat restoration site was divided into discrete habitat units following the procedures developed by Hankin and Reeves (1988). Width and depth at three transects, length, maximum depth, slope, and percent bedrock were measured for each habitat unit. Number of boulders in each channel unit were counted and placed into two size classes m and >2.0 m ( ft and >6.56 ft). Monumented photographic stations were established through the project site. Photographic stations were installed at 20-m (65.6-ft) intervals along the channel margins and marked with white PVC stakes. Photographs were taken upstream and downstream of each station from both the stream margin and a point in the center of the channel. Compass bearing, time of day, exposure settings, camera and lens type, and film type for each exposure were recorded so that duplication of each photograph would be possible at future dates. Additional photographs were taken of all locations where habitat restoration structures were to be constructed. Three time-lapse cameras were installed at Quartz Creek in December Exposure intervals of 15 minutes were set initially on the Super-8 movie cameras at Quartz Creek to document long-term changes in the stream bed. Exposure intervals were lengthened to 30 minutes in August 1991 to allow for longer intervals between changing film. These cameras are currently being maintained to visually record long-term changes at Quartz Creek. Channel hydraulics were measured using the fluorescent dye tracer rhodamine WT. A dye solution was injected into the stream at a constant rate until concentrations of dye were uniform throughout the stream reach. Dye injection was then terminated and the gradual decrease in dye 9

12 amounts at a downstream sampling station was recorded using a field fluorometer. Relative hydraulic retention can be calculated from the rate at which dye concentration increases during dye addition and decreases after termination of dye addition. Particulate retention was measured by adding known numbers of presoaked, neutrally buoyant ginkgo leaves (Ginkgo biloba) (Speaker 1985). A total of 4,000 ginkgo leaves were released at the top of each reach. A seine was placed 50 m (164 ft) downstream, and all leaves captured in the seine during a 2-hr interval were counted. A retention coefficient was calculated using the number of leaves added initially and the number recovered in the seine after 2 hr: L d = L o. e -kd L d = Percent of leaves in transport at distance d from release point L o = Percent of leaves released (100%) k = Retention coefficient d = Distance from release point (m) The project site was divided into six release reaches with distinct geomorphic characteristics (Table 1). Locations of dye and leaf introductions and fluorometer sampling sites in these six reaches were located on site maps so that retention measurements can be duplicated in successive years. All wood 1.0 m (3.28 ft) in length and 10 cm (3.94 in) in diameter was measured for length and diameter (minimum and maximum). Volume of each piece was calculated using the formula for a frustum of a paraboloid: 2 2 V = (D 1 + D2 ). L 8 V = Volume (m 3 ) D 1 and D 2 = Diameters at each end (m) L = Length (m) Each piece was tagged with numbered aluminum tags and location in the channel was recorded. 10

13 Table 1. Characteristics of reference 50-m reaches used to measure leaf retention in Quartz Creek. Reach location refers to distance along monumented baseline in meters; downstream boundary is designated as 0 meters. Structure numbers are specific accumulations located in reaches where retention was measured. Reach Type Reach Location Structure Number Accumulations Forest Site Deflector Old growth 10 V-Deflector 11 Sill logs 12 Lateral deflector Site Lateral deflector Old growth 19 Full-channel jam Site Upstream V Clearcut 25 Upstream V 26 Upstream V Site V-Deflector Clearcut 36 Parallel bank log Site Upstream V Clearcut Site Full-channel jam Old growth Channel cross-sections around log accumulations were not established until after project completion because of possible disturbance by the excavator (cross-sections are on file at Oregon State University). A minimum of one cross-section was established through each structure, and two or three transects were installed at more complex log accumulations, such as upstream V- shaped accumulations and full jams. Metal fence posts were placed above the active channel to permanently monument cross-section end points for future use and subsequent measurements. Notches in the metal posts were used to mark level reference lines for each transect. Aquatic insects were collected for the Willamette National Forest before and after wood installation in Collections of invertebrates have continued each summer since Samples were collected with a modified Hess sampler (25-cm diameter, 250-um mesh size) in riffles with a gravel/cobble substrate. A total of nine samples were taken on each date; three from the lower old-growth area, three from the clearcut area and three from the upper old-growth area. All samples were placed in whirl-pack containers and preserved with 95% ethanol. Invertebrate 11

14 samples are stored at Oregon State University. Invertebrate analysis was not part of this study and is not described in this report. In 1988 and 1989, fish abundance and distribution were determined by the snorkeling method (Hankin and Reeves 1988). Each channel unit was inventoried for fish by one diver and reinventoried by a second diver approximately 30 minutes later. Species, size, and habitat location were recorded for each fish observed. The restoration reach and adjacent reference reaches were snorkeled for direct fish observation in August in , 1996, and 1997 and diver estimates were calibrated by population estimation by electroshocking (Armour et al. 1983). RESULTS Characteristics Prior to Project Installation Forty-two individual habitat units were identified within the study site. Before structure installation, cascades were the dominant channel unit type comprising over 46% of the study area (Table 2). Other relatively high gradient habitat units, rapids and riffles, made up 24% and 14% of the reach respectively. Pools, an important habitat for fish, comprised only 10% of the entire reach. Side-channels, important habitat for fry rearing accounted for only 6% of the stream channel. Prior to the structure installation, 212 pieces of wood were found in the 1,100-m (3,609-ft) reach. This amount is relatively low compared to natural amounts in similar streams in the McKenzie River drainage. Mack Creek, a third-order stream in the H.J. Andrews Experimental Forest, has over 1,666 pieces of wood in a 1,000-m (3,281-ft) reach. Volume of all existing wood at Quartz Creek was m 3 /m 2 (10.4 ft 3 /ft 2 ) of active stream channel while the volume of wood at Mack Creek was m 3 /m 2 (93.4 ft 3 /ft 2 ) of active stream channel. Areas above and below the restoration site contained higher amounts of wood, but all three reaches of Quartz Creek had similar amounts of wood after log installation in

15 Table 2. Channel unit distribution before and after wood installation at Quartz Creek restoration site in Pre-Installation Unit Type # Percent of Length Post-Installation # Percent of Length Pool Riffle Rapid Cascade Side-Channel Of the 212 pieces of pre-existing wood, only 70 pieces had >25% of their volume within the active channel. A large portion of the pieces of wood was located on the active channel terrace or perched above the active channel. These pieces of wood had little or no effect on the stream and provided little or no habitat for fish. The fish community at Quartz Creek restoration site includes cutthroat trout, rainbow and steelhead trout, and Paiute sculpins (Cottus beldingi). Cutthroat trout are the dominant salmonid in the restoration reach, making up 90% of total fish numbers. One adult steelhead was observed in a pool (Pool-25) located in the upper clearcut reach in August of 1988 and Bull trout were observed in lower Quartz Creek near the confluence with the McKenzie River, but none were found in the habitat restoration site. In the summer before structure installation, trout densities averaged 66 fish/100 m (20 fish/100 ft) of stream in the restoration reach. Densities of fish/100 m (15-46 fish/100 ft) have been recorded for similar streams in the H. J. Andrews Experimental Forest (Lookout Creek and Mack Creek). Pool habitats held the greatest densities of trout at 111 fish/100 m (34 fish/100 ft), while the lowest density of trout occurred in cascade habitats at 59 fish/100 m (18 fish/100 ft). Riffles and rapids contained intermediate densities with 75 fish /100 m (23 fish/100 ft) and 69 fish/100 m (21 fish/100 ft), respectively. 13

16 Size frequency distribution of fish in 1988 exhibited reduced proportions of fry and older fish and was dominated by 10.2 to 12.7 cm (4 to 5 in) fish (Figure 4). Rainbow trout in the system were slightly larger in size than the cutthroat. The largest individuals observed, other than the one steelhead, were several 28 cm (11 in) rainbow trout usually in deep pools associated with cover. The most numerous trout were in the cm (4-5 in) class corresponding to 1+ year age class. Project Installation Log and boulder accumulations were installed in October of Trees were felled in a section of old-growth forest (non-riparian) 0.8 km (0.5 miles) from the project site and transported by a D-8 Caterpillar to locations along the stream. Boulders used to stabilize log accumulations were obtained from the immediate channel area. Twenty-five root-wads from an adjacent quarry also were used in structure construction. A track-driven hydraulic excavator prepared the streambed for log introductions and placed individual logs in position. A "trash rack" was installed below the project site to minimize possible downstream movement of logs and potential risks to bridges lower in the system. Tree species used for log accumulations consisted of western red cedar (Thuja plicata), Douglas-fir (Pseudotsuga menziesii), western hemlock (Tsuga heterophylla), and bigleaf maple (Acer macrophyllum). Cedar logs (n = 105) were used extensively because of their slow decomposition rate and Douglas-fir logs (n = 77) were used when very large diameter logs were required. Western hemlock (n = 3) and big leaf maple (n = 1) were rarely used because of their faster decomposition rates. 14

17 QUARTZ CREEK REHABILITATION SITE SIZE FREQUENCY OF FISH - JULY NUMBER OF FISH (Hundreds) LENGTH (inches) Figure 4. Size distribution of cutthroat and rainbow trout in Quartz Creek restoration site, July

18 Installation of Wood Accumulations A total of 48 log accumulations were installed in Quartz Creek using 186 pieces of wood. The volume of wood installed was m 3 /m 2 (35.8 ft 3 /ft 2 ) of active stream channel. Two additional sites were modified by boulder placement alone. Various types of log accumulations and degrees of cabling were used to evaluate effectiveness and longevity of different types of material installations (Figures 5a-d and 6a-c). Seven types of log accumulations, some designed to resemble natural woody accumulations, were used in the project: Full-channel dams Lateral deflectors Lateral V-shaped deflectors Upstream V-shaped accumulations Sill logs Cover logs Parallel bank logs Three degrees of cabling (full cable, partial cable, and no cable) were applied to each type of structure in the project reach (Table 3). Table 3. Number of log accumulations of different types and cabling used in Quartz Creek in October Structure Full Cable Partial Cable No Cable Full-channel dam Lateral deflector Lateral V-shaped deflector Sill log Upstream V-shaped accumulation Cover log Parallel bank log Road log Full-channel dams consisted of accumulations of wood that spanned the entire bankfull channel. Lateral deflectors were small accumulations anchored on one bank and extending into the wetted channel. A lateral V-shaped deflector was similar to a lateral deflector but included a downstream log intersecting at the point of the V. A sill log spanned the channel and lay directly 16

19 Figure 5a-b. Single log accumulations installed at Quartz Creek restoration site, October Top: Sill log structure. Bottom: Pool cover log structure. 17

20 Figure 5 c-d. Single log accumulations installed at Quartz Creek restoration site, October Top: Parallel bank log. Bottom: Lateral deflector. 18

21 Figure 6 a-b. Multiple log accumulations installed at Quartz Creek restoration site, October Top: Upstream V accumulation. Bottom Lateral V shaped accumulation. 19

22 Figure 6 c. Full channel jam accumulation installed at Quartz Creek restoration site, October

23 on the surface of the streambed, creating a sill. An upstream V-shaped accumulation was two or more logs that spanned the channel and intersected at a point upstream of their base. Cover logs were generally small accumulations of logs placed in pools to create overhead cover for fish. Parallel bank logs were single logs placed on the edge of the wetted channel against the bank to create small amounts of lateral cover at low flow. Road logs were placed at the intersection of the temporary skid roads and the active stream channel to prevent encroachment of the stream onto the roadbed. Location and position of each structure were added to the maps of Quartz Creek. Changes in channel geomorphology and movements of boulders and pre-existing wood by the excavator were also recorded on the existing project maps to provide a final map. Addition of the 48 log accumulations trapped a large amount of wood within the active channel (Table 4). Table 4. Large wood characteristics at Quartz Creek before and after structure installation. Characteristic Prior to Project Installed by Project After Project Accumulations Full Channel dams Total Pieces of Logs in Channel (>25%) Logs 10 m long and 75 cm wide Logs 6 m long and 60 cm wide Several photographic stations were destroyed by machinery and required careful replacement. A complete set of photographs was retaken from each photopoint station. Photographs were taken every year of each specific structure site to document changes in substrate composition and channel hydraulics. All photographs are 35-mm slides and have been labeled and archived at Oregon State University. 21

24 Immediate changes in channel unit composition were observed when the 1,100-m (3,609-ft) reach was reinventoried in 1988 for habitat unit composition. Four additional pool habitat units were created in units that previously were cascades. Proportion of pool length over the entire reach increased from 10% to 16%, and length of stream in cascade habitat units decreased from 46% to 40%. Areas that originally were long, high velocity cascades were converted to a stair-stepped longitudinal profile by wood placement. Habitat unit lengths of riffles, rapids, and side channels remained relatively unchanged. Late installation of logs in 1988 because of fire danger minimized the time available to remeasure channel composition and fish abundance before high stream flows. Substantial increases in discharge in November terminated the fish survey and retention studies. Higher discharges in late fall prevented comparison with data collected at low discharges prior to log introduction. Responses after Project Installation ( ) The Quartz Creek habitat restoration site had detailed monitoring conducted each summer from 1989 to In 1994 and 1995 a reduced survey of the restoration reach was conducted measuring channel units and movement of wood. In the summers of 1996 and 1997 complete surveys were conducted again. The survey conducted in the summer of 1996 measured changes at the site as a result of the February 1996 flood and sampling in the summer of 1997 measured changes from the November 1996 flood. All geomorphic and biological parameters were remeasured in the same manner as in the pre-introduction data collection. Photographs were taken from all monumented photopoints. Time-lapse camera systems have been maintained throughout the period. Influences of high water discharges on three types of log accumulations have been recorded. Though quantitative measurements are difficult to derive from these time-lapse films and photopoint photographs, valuable qualitative information on relative movement of large wood has been obtained. 22

25 Starting in 1989, we surveyed additional distances of 400 m (1,312 ft) below and 1,500 m (4,922 ft) above the 1,100-m (3,609 ft) habitat restoration site with the Hankin-Reeves stream survey methodology. Length of pool habitat in the restoration site increased from 10% before structure installation to 21% by 1993 (Table 5). Pool habitat remained relatively stable in both 1994 and 1995 at 20% and 18% respectively. After the February 1996 flood, length of habitat in pools decreased to 15% in the summer of 1996 but increased to 16% after the November 1996 flood. Quality of pool habitat also increased with a mean maximum depth of 0.76 m (2.5 ft) before structure installation to 1.04 m (3.4 ft) in 1993, 0.98 m (3.2 ft) in 1994, and 1.10 m (3.6 ft) in After the February 1996 flood the mean maximum depth of pools was 0.92 m (3.0 ft) and after the November 1996 flood the mean maximum depth returned to 1.04 m (3.4 ft). Length of side-channel habitat changed significantly over the first 5-yr period. Before structure installation, 6% of channel length in the restoration site was in side-channels; but in 1993, 23% of the total length of stream channel was side-channel habitat. After the February 1996 flood, 34% of the total length of stream channel was side-channel habitat, but in 1997 side-channel habitat was reduced to 26%. Total area of side-channels accounted for 161 m 2 (1,732 ft 2 ) in 1988 (2.0% of total wetted channel) and 589 m 2 (6,338 ft 2 ) in 1993 (6.2% of total wetted channel). In both 1994 and 1995, side-channels accounted for 8.4% of the wetted channel. After the February 1996 flood, side-channels accounted for 1,331 m 2 (14,322 ft 2 ), (13.3% of total wetted channel); but after the November 1996 flood, side channels accounted for 752 m 2 (8,092 ft 2 ), (8.1% of total wetted channel). 23

26 Table 5. Total length of channel units (m) for the below restoration reach, restoration reach, and above restoration reach at Quartz Creek for 1988, Total length is the sum of main channel and side channel (SC) lengths. Percentage of total wetted channel length for each habitat unit type is included in parentheses. BELOW RESTORATION REACH Channel Unit 1989 (%) 1993 (%) 1994 (%) 1995 (%) 1996 (%) 1997 (%) Pool 40 (10) 84 (16) N/A N/A N/A N/A 73 (11) 100 (15) Glide 0 (0) 17 (3) N/A N/A N/A N/A 0 (0) 12 (2) Riffle 57 (15) 129 (25) N/A N/A N/A N/A 232 (36) 224 (33) Rapid 130 (33) 251 (48) N/A N/A N/A N/A 185 (28) 92 (14) Cascade 162 (41) 0 (0) N/A N/A N/A N/A 97 (15) 166 (24) SC 0 (0) 41 (8) N/A N/A N/A N/A 37 (6) 63 (9) Step 2 (1) 4 (<1) N/A N/A N/A N/A 23 (4) 21 (3) Total (m) RESTORATION REACH Channel Unit 1988 (%) 1993 (%) 1994 (%) 1995 (%) 1996 (%) 1997 (%) Pool 116 (10) 280 (21) 273 (20) 251 (18) 237 (15) 221 (16) Glide 0 (0) 17 (1) 16 (1) 12 (1) 17 (1) 0 (0) Riffle 157 (14) 201 (15) 195 (14) 180 (13) 252 (16) 216 (16) Rapid 264 (24) 329 (24) 271 (20) 262 (19) 234 (15) 262 (19) Cascade 509 (46) 197 (14) 249 (19) 289 (21) 259 (17) 275 (20) SC 69 (6) 315 (23) 313 (23) 351 (26) 531 (34) 367 (26) Step 0 (0) 30 (2) 37 (3) (26) (2) 32 (2) 43 (3) Total (m) 1,115 1,369 1,354 1,371 1,562 1,384 ABOVE RESTORATION REACH Channel Unit 1989 (%) 1993 (%) 1994 (%) 1995 (%) 1996 (%) 1997 (%) Pool 264 (17) 220 (13) N/A N/A N/A N/A 343 (18) 256 (15) Glide 0 (0) 39 (2) N/A N/A N/A N/A 0 (0) 0 (0) Riffle 65 (5) 127 (8) N/A N/A N/A N/A 206 (11) 127 (8) Rapid 459 (30) 294 (18) N/A N/A N/A N/A 199 (11) 204 (12) Cascade 725 (47) 965 (58) N/A N/A N/A N/A 1001 (54) 1028 (60) SC 0 (0) 21 (1) N/A N/A N/A N/A 85 (5) 59 (3) Step 15 (15) 9 (<1) N/A N/A N/A N/A 26 (1) 33 (2) Total (m) 1,528 1,675 1,860 1,707 24

27 Behavior of Large Wood Accumulations As of 1993 only 21 of the 186 pieces of wood originally installed (11.8%) had been transported out of the restoration reach. After the November 1996 flood, two additional pieces of introduced wood were transported out of the restoration reach. Of the 48 instream log accumulations installed in Quartz Creek, 22 log accumulations "moved" during flood discharges. Operationally, we defined "movement" of an accumulation as transport of pieces within a structure one meter or greater downstream. Logs used as road blocks were not included in the analyses but were reported in Table 6. The relative degree of cabling in the log accumulations did not affect tendency for structures to move. Of the 20 log accumulations (excluding road block logs) that moved more than 1 m (3.28 ft), nine were completely cabled, six were partially cabled, and five were not cabled. If a distance of 10 m (33 ft) or greater is used for classifying a structure as moving, only eight structures moved: two fully cabled, three partially cabled, and four non-cabled (Table 6). The distance logs moved downstream differed for the three degrees of cabling applied. Transported logs from fully cabled structures moved an average distance of 55 m or 180 ft (n = 18 logs; mean length = 10.5 m or 34.5 ft; mean diameter = 0.78 m or 2.6 ft). Logs in partially cabled structures that were transported moved an average distance of 93 m or 305 ft (n = 11 logs; mean length = 8.5 m or 27.9 ft; mean diameter = 0.76 m or 2.5 ft). Transported logs that were in accumulations with no cabling moved an average of 246 m or 807 ft (n = 27; mean length = 5.7 m or 18.7 ft; mean diameter = 0.69 m or 2.3 ft). The maximum distance a fully cabled log moved was 620 m or 2,034 ft (7.4 m or 24.3 ft long, 0.80 m or 2.6 ft diameter). The maximum distance a partially cabled log moved was 295 m or 968 ft (4.8 m or 15.7 ft long, 0.60 m or 2.0 ft diameter). The maximum distance an uncabled log moved was 1,000 m or 3,281 ft (2.3 m or 7.5 ft long, 0.45 m or 1.5 ft diameter). Most of the accumulations that moved or shifted less than 10 m (33 ft) downstream are still performing the original objectives they were designed to perform. Logs that moved downstream greater distances tended to function differently than the original planned objective. 25

28 The flood of February 1996 deposited an additional log accumulation in the middle of the restoration reach. A log 10.0 m (32.8 ft) long and 0.26 m (0.85 ft) in diameter was deposited perpendicular to the stream flow along with several other pieces at the 590 m (1,936 ft) position on the baseline maps. A large plunge pool was formed behind this new accumulation in 1996 and has deepened and enlarged in Table 6. Characteristics of log accumulations that moved 1 meter in Quartz Creek from September 1988 to 1993, 1996, and Logs used as road blocks were not included in analyses of movement. Structure Type and Number Degree of Cabling 1993 Distance Moved (m) 1996 Distance Moved (m) 1997Distance Moved (m) Full Jam (#2) Partial Lateral Deflector (#3) Full Upstream V (#5) None Parallel Bank (#6) None Pool Cover (#8) Partial Lateral Deflector (#9) Full Sill Log (#11) Full Pool Cover (#13) None Pool Cover (#20) None V Deflector (#23) None Upstream V (#24) Partial Upstream V (#25) Full Pool Cover (#29) Full V Deflector (#35) Partial Parallel Bank (#36) Full Parallel Bank (#40) Full Upstream V (#42) Partial Lateral Deflector (#46) Partial Upstream V (#48) Full Full Jam (#50) Full Road Block (#28) None Road Block (#30) None

29 Retention of Water and Particulate Material Dye releases performed before log introductions showed that hydraulic retention was relatively low in the high gradient single channel sections of the study site. Particulate retention was lowest in the bedrock chute area opposite the quarry. Hydraulic and particulate retention were somewhat higher in those reaches that contained side-channels or in areas where some wood was present in the channel. In reaches where dye concentrations rapidly approached a maximum asymptotic concentration, hydraulic retention was low. Hydraulic retention was greater when the time to reach asymptotic concentrations took longer. Measurements of channel hydraulics and retention were conducted again in 1996 and 1997 in the same six reaches that were analyzed before structure installation (Figures 7a-f). Though the same stock concentration of dye and rate of injection were used as in previous years, asymptotic concentrations varied from year to year due to changes in stream discharge. When constant dye injection rates are used during lower stream flows, observed concentrations of dye increase. Stream discharge (Q) is calculated using the rate of injection, the concentration of dye injected, and the measured concentration of dye in the stream at asymptotic concentration at the downstream sampling site (Kilpatrick 1967). Discharges in mid-summer ranged from m 3 /s ( ft 3 /s) during the first 5 years of the project, averaging 0.20 m 3 /s (6.9 ft 3 /s) (Table 7). In 1996 summer discharges were low with an average of 0.08 m 3 /s (2.66 ft 3 /s). Flows increased in the summer of 1997 with an average discharge of 0.14 m 3 /s (4.98 ft 3 /s). Table 7. Discharge rates (ft 3 /s) for Quartz Creek from 1988 to 1993, 1996, and Stream Reach Site # Site # Site # Site # Site # Site # Mean

30 QUARTZ CREEK DYE RELEASES RELEASE REACH # DYE CONC. (ppb) TIME (minutes) Figure 7a. Dye release curves for release reach 1 at Quartz Creek restoration site, 1988, 1993, 1996, and Arrow indicates maximum asymptotic concentration for dye release in

31 QUARTZ CREEK DYE RELEASES RELEASE REACH # DYE CONC. (ppb) TIME (minutes) Figure 7b. Dye release curves for release reach 2 at Quartz Creek restoration site, 1988, 1993, 1996, and

32 QUARTZ CREEK DYE RELEASES RELEASE REACH # DYE CONC. (ppb) TIME (minutes) Figure 7c. Dye release curves for release reach 3 at Quartz Creek restoration site, 1988, 1993, 1996, and

33 QUARTZ CREEK DYE RELEASES RELEASE REACH # DYE CONC. (ppb) TIME (minutes) Figure 7d. Dye release curves for release reach 4 at Quartz Creek restoration site, 1988, 1993, 1996, and

34 QUARTZ CREEK DYE RELEASES RELEASE REACH # DYE CONC. (ppb) TIME (minutes) Figure 7e. Dye release curves for release reach 5 at Quartz Creek restoration site, 1988, 1993, 1996, and

35 QUARTZ CREEK DYE RELEASES RELEASE REACH #6 25 DYE CONC. (ppb) TIME (minutes) Figure 7f. Dye release curves for release reach 6 at Quartz Creek restoration site, 1988, 1993, 1996, and

36 Particulate retention was measured each year by releasing 4,000 ginkgo leaves in the same reaches as in Particulate retention generally increased in the six reaches after the addition of the log accumulations (Table 8). Retention of particulate material is greater when the value of the retention coefficient (k) increases. Average leaf travel distance (1/k) decreased in all six reaches between 1988 and 1989 (Table 9). In 1988, the average leaf traveled approximately 83 m (272 ft); but the travel distances decreased to an average of less than 40 m (131 ft) from 1989 to In 1996 the average leaf travel distance was 24 m (79 ft) but increased to 33 m (108 ft) in 1997 (Figure 8). Table 8. Retention coefficient (k) for particulate retention releases at Quartz Creek restoration site from , 1996, and Stream Reach Site # Site # Site # Site # Site # Site # Mean Table 9. Average leaf travel distance (1/k) in meters in reference reaches of Quartz Creek restoration site from 1988 to 1993, 1996, and Stream Reach Site # Site # Site # Site # Site # Site # Mean

37 QUARTZ CREEK PARTICULATE RETENTION MEAN AVERAGE LEAF TRAVEL DISTANCE (m) YEAR Figure 8. Mean average leaf travel distance (1/k) in meters at Quartz Creek restoration site, , 1996, and

38 Wood that entered the study site continued to be retained by the log accumulations (Figure 9 and 10). By 1997, log accumulations had retained sufficient amounts of new wood to restore the size class distribution of wood in the Quartz Creek restoration site to levels observed in streams in oldgrowth forests in the basin. Using Mack Creek in the H.J. Andrews Experimental Forest as a reference, amounts of wood in Quartz Creek in 1997 were similar to the amounts of wood in Mack Creek (Figures 11a-c and 12a-c). A total of 526 new pieces of wood (mean length = 2.34 m or 7.68 ft; mean diameter = 0.24 m or 0.79 ft) were retained within the restoration site from the February 1996 flood. A total of 93 pieces of wood left the restoration reach (mean length = 2.29 m or 7.51 ft, mean diameter = 0.24 m or 0.79 ft) resulting in a net gain of 433 pieces of wood for In the winter of , with the large November flood, a total of 427 pieces of wood were deposited (mean length = 2.31 m or 7.60 ft, mean diameter = 0.26 m or 0.85 ft) within the restoration reach. A total of 379 pieces of wood left the restoration reach (mean length = 2.37 m or 7.78 ft, mean diameter = 0.24 m or 0.79 ft) resulting in a net gain of 48 pieces of wood for The most efficient structure to date that traps large wood is the non-cabled full jam (Structure #19) located in the middle of the restoration site. The jam was originally constructed with 20 pieces of wood. The jam contained 39 pieces in 1989, 97 pieces in 1990, 100 pieces in 1991, 130 pieces in 1992, 163 pieces in 1993, 162 pieces in 1994, 182 pieces in 1995, 280 pieces in 1996, and 311 pieces of large wood in Pieces of wood retained in the restoration reach were more likely to become incorporated into accumulations rather than to be deposited singly. In 1994, 68 pieces of wood entered the restoration reach; 50 pieces (74%) were incorporated into accumulations. In 1995, 160 pieces entered the reach with 121 pieces (76%) occurring in accumulations. In 1996, 526 pieces entered the reach and 455 pieces (87%) occurring stored in accumulations. In 1997, 427 pieces entered the reach and 362 pieces (85%) were incorporated into accumulations. The volume of wood in 1994 in Quartz Creek was m 3 /m 2 (44.83 ft 3 /ft 2 ) of active stream channel and in 1995, total volume of wood was m 3 /m 2 (41.57 ft 3 /ft 2 ) of active stream channel. In 1996, total volume of wood was m 3 /m 2 (48.05 ft 3 /ft 2 ) of active 36

39 stream channel, and in 1997 total volume of wood was m 3 /m 2 (51.67 ft 3 /ft 2 ) of active stream channel. 37

40 QUARTZ CREEK RESTORATION SITE RETENTION OF WOOD 400 NUMBER OF PIECES LENGTH (meters) Figure 9. Size class distribution (length) of wood retained in Quartz Creek restoration site,

41 QUARTZ CREEK RESTORATION SITE RETENTION OF WOOD 400 NUMBER OF PIECES DIAMETER (meters) Figure 10. Size class distribution (diameter) of wood retained in Quartz Creek restoration site,

42 LARGE WOOD LOADING LEVELS QUARTZ CREEK VS. MACK CREEK 6 NUMBER OF LOGS / 1000 m (Hundreds) LENGTH (m) MACK CREEK PRE-REHAB QUARTZ Figure 11a. Size class distribution (length) of wood at Mack Creek and Quartz Creek restoration site before structure installation. 40

43 LARGE WOOD LOADING LEVELS QUARTZ CREEK (OCT 1988) VS. MACK CREEK 6 NUMBER OF LOGS / 1000 m (Hundreds) LENGTH (m) MACK CREEK QUARTZ CREEK Figure 11b. Size class distribution (length) of wood at Mack Creek and Quartz Creek restoration site immediately after structure installation. 41

44 LARGE WOOD LOADING LEVELS QUARTZ CREEK AND MACK CREEK NUMBER OF LOGS / 1000 METERS (Hundreds) LENGTH (meters) MACK QUARTZ Figure 11c. Size class distribution (length) of wood at Mack Creek and Quartz Creek restoration site, October

45 LARGE WOOD LOADING LEVELS QUARTZ CREEK VS. MACK CREEK 4 NUMBER OF LOGS / 1000 m (Hundreds) DIAMETER (m) MACK CREEK PRE-REHAB QUARTZ Figure 12a. Size class distribution (diameter) of wood at Mack Creek and Quartz Creek restoration site before structure installation. 43

46 LARGE WOOD LOADING LEVELS QUARTZ CREEK (OCT 1988) VS. MACK CREEK 4 NUMBER OF LOGS / 1000 m (Hundreds) DIAMETER (m) MACK CREEK QUARTZ CREEK Figure 12b. Size class distribution (diameter) of wood at Mack Creek and Quartz Creek restoration site immediately after structure installation. 44

47 LARGE WOOD LOADING LEVELS QUARTZ CREEK AND MACK CREEK NUMBER OF LOGS / 1000 m (Hundreds) DIAMETER (m) MACK QUARTZ Figure 12c. Size class distribution (diameter) of wood at Mack Creek and Quartz Creek restoration site, October

48 Change in Channel Morphology Overall depth and composition of the streambed remained relatively stable, but fine gravel (smaller than the dominant cobble substrate) was deposited or scoured at several locations. Various log accumulations, such as upstream "V"s and some lateral deflectors, had deep pools scoured out below them. Sediments have continued to accumulate above the sill logs in the reach dominated by bedrock before restoration and above the full channel jam located in the middle of the restoration reach. In the 47 channel cross-sections, depth was monitored at 1,818 individual points (Table 10). In 1996, the maximum scour that occurred at any point was 1.62 m (5.32 ft) at a lateral deflector and in 1997 the maximum scour of 1.76 m (5.77 ft) occurred at another lateral deflector near the top of the restoration reach. The greatest amount of deposition in 1996 at any monitored point was 2.12 m (6.96 ft) above a full channel jam and in 1997 the maximum deposition of 2.35 m (7.71 ft) occurred at the same full channel jam. Maximum net scour in 1996 for an entire transect was 0.61 m (2.00 ft) at a V-deflector, and the greatest net deposition for a transect was 0.70 m (2.30 ft) above a full channel jam. Maximum net scour in 1997 for an entire transect was 0.42 m (1.38 ft) at a V- deflector, and the greatest net deposition for a transect was 0.75 m (2.46 ft) above a full channel jam. In 1996, maximum scour of more than 1.0 m (3.28 ft) occurred at 11 of the 47 total transects, and maximum deposition of more than 1.0 m occurred at 8 transects. In 1997, maximum scour of more than 1.0 m occurred at 12 transects, and maximum deposition of more than 1.0 m occurred at 8 transects. More than 10 cm (3.94 in) was scoured (net for entire transect) at 11 transects by 1996, and 12 transects experienced a net deposition of more than 10 cm (3.94 in). More than 10 cm (3.94 in) was scoured (net for entire transect) at 11 transects by 1997, and 17 transects experienced a net deposition of more than 10 cm (3.94 in). The average change in streambed height for all transects by 1996 was a deposition of m (0.043 ft). The average change in streambed height for all transects by 1997 was a deposition of m (0.092 ft). 46

49 Table 10. Scour and deposition of substrates at 47 cross-sections in the restoration reach at Quartz Creek for 1996 and All values are in meters. Cross Section 1996 Maximum Scour 1996 Maximum Deposition 1996 Net Change 1997 Maximum Scour 1997 Maximum Deposition 1997 Net Change n

50 Overall streambed height did not change substantially. However, net changes of more than 10 cm (3.94 in) occurred at 51% of the transects in 1996, and maximum changes of more than 1.0 m 3.28 ft) were observed at 38% of the monitored transects. Net changes of more than 10 cm (3.94 in) occurred at 60% of the transects in 1997 with maximum changes of more than 1.0 m (3.28 ft) observed at 35% of the monitored transects. Changes in Trout Populations In both 1996 and 1997 fish abundance and distribution were analyzed in the restoration site. The 1,500-m (4,922-ft) section immediately above and the 400-m (1,312-ft) section immediately below the restoration site also were analyzed. Based on snorkel data, average fish densities before structure installation within the restoration site were 66 fish/100 m (20 fish/100 ft) (Table 11, Figure 13). Fish densities in the restoration reach moderated from 1988 to 1993 with the highest density occurring in 1991 with 127 fish/100 m (39 fish/100 ft). Fish densities from snorkel data in 1996 were 109 fish/100 m (33 fish/100 ft) and in 1997 fish densities increased to 135 fish/100 m (41 fish/100 ft), the highest density thus recorded in the restoration site. Over the first five years since structure installation, fish densities were usually highest in the 400-m (1312-ft) section below the restoration site. Densities were lowest in the section above the restoration site for the same time interval. In both 1996 and 1997, fish densities were highest in the restoration reach, next highest in the reach below the restoration reach, and lowest in the 1,500- m (4,922-ft) reach above the restoration reach. Fish densities were the highest in pool habitats in all years for all reaches with the exception of the below restoration reach in 1989 and the above restoration reach in 1996 (Table 12). 48

51 QUARTZ CREEK TROUT OBSERVED BY DIVERS TROUT/100 m YEAR BELOW RESTORATION RESTORATION ABOVE RESTORATION Figure 13. Cutthroat and rainbow trout densities based on snorkel counts in the above restoration site, restoration site, and the below restoration site, , 1996, and

52 Table 11. Number of trout/100 meters of stream (based on snorkel counts) for three sites at Quartz Creek from 1988 to 1993, and 1996 to Study Site Below Restoration Site NA Restoration Site Above Restoration Site NA Size frequency distributions were developed from data on visual estimates of fish size during snorkeling observations. Size frequency of trout in 1993 (Figure 14) resembled those observed prior to restoration. Larger numbers of fry were observed in 1996 (Figure 15) and fry numbers increased in 1997 (Figure 16). The largest fish observed by snorkeling was seen in Ten fish over 12 inches (30 cm) were observed in the restoration reach in August Fish of this size have not been seen in the restoration site in all previous observations. 50

53 Table 12. Number of cutthroat and rainbow trout/100 m in different habitat types observed by snorkeling at Quartz Creek from 1988 to 1993, 1996 to BELOW RESTORATION REACH Channel Unit Type Pool N/A Glide N/A Riffle N/A Rapid N/A Cascade N/A Side-Channel N/A 4.9 Step N/A RESTORATION REACH Channel Unit Type Pool Glide Riffle Rapid Cascade Side-Channel Step ABOVE RESTORATION REACH Channel Unit Type Pool N/A Glide N/A Riffle N/A Rapid N/A Cascade N/A Side-Channel N/A Step N/A

54 QUARTZ CREEK RESTORATION SITE SIZE FREQUENCY OF FISH - AUGUST NUMBER OF FISH (Hundreds) LENGTH (inches) Figure 14. Size frequency distribution of cutthroat and rainbow trout in Quartz Creek restoration site based on diver observations, August

55 QUARTZ CREEK RESTORATION SITE SIZE FREQUENCY OF FISH - AUGUST NUMBER OF FISH (Hundreds) LENGTH (inches) Figure 15. Size frequency distribution of cutthroat and rainbow trout in Quartz Creek restoration site based on diver observations, August

56 QUARTZ CREEK RESTORATION SITE SIZE FREQUENCY OF FISH - AUGUST NUMBER OF FISH (Hundreds) LENGTH (inches) Figure 16. Size frequency distribution of cutthroat and rainbow trout in Quartz Creek restoration site based on diver observations, August

57 The restoration site was electroshocked to validate the accuracy of snorkel counts by divers in 1990, 1991, 1992, 1993, 1996, and Pass-removal method was used as the fish population estimator. The ratio of population estimates from snorkeling to those derived from electroshocking provided correction factors for each habitat type for each year (Table 13). A correction factor of <1.0 indicates that divers observed more fish than were estimated by electroshocking; values >1.0 indicate that electroshocking estimated more fish, and a value of 1.0 indicates that both methods estimated the exact same population. With the exception of cascades and steps, correction factors for 1996 and 1997 were lower than in Table 13. Factors for correcting diver counts to fish populations (as determined by electrofishing estimates) for habitat types in Quartz Creek for , 1996, Unit Type Pool Glide Riffle Rapid Cascade Side-Channel Step Total fish populations for the entire restoration reach were estimated by applying the correction factors to snorkel counts obtained in the three study sites. In 1991, trout populations were highest in the section immediately below the restoration site, and populations within the restoration site were only slightly greater than those upstream (Table 14, Figure 17). In 1992, trout populations declined in all three sites, especially in the site below the restoration reach. In 1993, trout populations decreased at all three sites but the decline in the restoration site was proportionately less than in adjacent reaches (6% in the restoration reach versus 20% above and 26% below). In 1996, large increases in trout populations were observed in the restoration site, 55

58 slight increases in the reach below the restoration site, and decreases in the section immediately above the restoration site. In 1997, trout populations increased in all three sites with the largest increase occurring in the section immediately above the restoration reach. The restoration reach had the highest density of trout in 1992, 1993, 1996, and Table 14. Number of fish/100 meters corrected for diver observation efficiencies at Quartz Creek for 1990, 1991, 1992, 1993, 1996, and Study Reach Below Restoration Restoration Site Above Restoration The density of fish increased in all habitat types in both 1996 and 1997 from 1993 densities with the exception of side-channels and steps (Table 15). Pool habitat held the highest density fish with 330 fish/100 m (101 fish/100 ft) of pool habitat in 1996 and 264 fish/100 m (80 fish/100 ft) in The next highest density of fish was in riffle habitat, followed by rapids. Table 15. Numbers of fish/100 meters of each habitat type in Quartz Creek restoration site corrected from electroshocking data for 1990, 1991, 1992, 1993, 1996, and Habitat Type Pool Glide Riffle Rapid Cascade Side-Channel Step

59 QUARTZ CREEK CORRECTED DIVER ESTIMATES TROUT / 100 m (Hundreds) YEAR BELOW RESTORATION RESTORATION ABOVE RESTORATION Figure 17. Corrected diver estimates of trout densities at Quartz Creek in the above restoration site, restoration site, and below restoration site, *Values for 1988 and 1989 restoration site derived from applying mean correction values obtained in

60 The narrow width of side-channels can make the density of fish appear to be low when using number of fish/100 m. Density of fish expressed as number/m 2 of wetted channel can be very high in narrow habitats such as side-channels. Side-channels held the highest density of fish in 1991 with 0.38 fish/m 2 (4.09 fish/ft 2 ); 0.76 fish/m 2 (8.16 fish/ft 2 ) in 1993; and 0.43 fish/m 2 (4.67 fish/ft 2 ) in Table 16. Numbers of fish/m 2 of each habitat type in Quartz Creek restoration site corrected from electroshocking data for 1990, 1991, 1992, 1993, 1996, and Habitat Type Pool Glide Riffle Rapid Cascade Side-Channel Step

61 DISCUSSION Performance of Log Structures Time-lapse photography of wood accumulations during high winter flows on Mack Creek (H.J. Andrews Experimental Forest) shows that natural wood dams rise and fall with changing stream discharge. During high discharges, these log accumulations float up and the majority of water passes underneath. On the falling limb of the hydrograph, the pieces fall back into place, and it is often difficult to discern any changes. Logs inundated by higher flows naturally tend to float, and any logs that are artificially bound to the streambed are subjected to high flotation forces. Structures that are not cabled or partially cabled can move and adjust to the directions and intensity of the force of flowing water. The upstream-v log accumulations installed at Quartz Creek effectively created a step-pool profile in long cascades, but they had to take the full force of high winter discharges because of their design. Five of the 21 log accumulations that moved were of this type. The V configuration focused the force of the flow to the middle of the channel and quickly scoured sediments. In most cases, this scour cuts back under the structure and caused upstream sediment deposits to give way under the structure and changed the arrangement of wood in the accumulation. In one instance a secondary or flood channel formed during high flows around an upstream "V". Flows down these secondary channel take some pressure off log accumulations in the main channel during high water events. The structures that the highest tendency to move or shift were the upstream-v accumulations (5 of 6), followed by full jams (2 of 3), sill logs (1 of 2), and cover logs (4 of 8). Large amounts of spawning gravel continue to accumulate in association with installed structures. The upstream-v log accumulations had large amounts of potential spawning gravel deposited below them on the sides of the stream during winter discharges (Figure 18a-d). Directly below the tip of the upstream-v log accumulations, deep plunge pools were scoured. The full channel jam in the middle of the restoration reach had over 2 m (6.56 ft) of sand and gravel 59

62 Figure 18 a - b. Top: Site of proposed upstream V structure at Quartz Creek, July Bottom: Same site with upstream V structure installed, October

63 Figure 18 c - d. Top: Upstream V structure at Quartz Creek, September Bottom: Upstream V structure at Quartz Creek, September

64 deposited directly upstream of the jam. Spawning gravel was deposited for a distance of 20 m (66 ft) upstream of this jam. Lateral deflectors had spawning gravel deposited below them for various distances. The retention of large amounts of wood by the non-cabled full channel jam (Structure #19) in the middle of the restoration site continues to be encouraging (Figure 19a-f). The number of logs increased more than fifteen-fold in nine years. In appropriate reach locations, these types of jams provide more natural habitat than heavily cabled "trash racks" and still effectively capture floating wood during high flows. The non-cabled full channel jam grew from 20 logs to 311 logs in nine years, while the trash rack of nine logs accumulated 38 logs. Accumulations of a few large logs will not capture wood from transport as effectively and will not create complex habitats as quickly as more complex accumulation of logs. The sill log structure (Structure #11) has preformed well in trapping sediment on top of the bedrock substrate that was present at this location in 1988 (Figure 20a-b). A large deep pool has been formed behind this sill log structure. In 1988, a total of three trout were present at this bedrock dominated site but the trout density increased at this site to 67 trout by The maximum distance that a piece of wood from the Quartz Creek restoration site has moved is at least 40 km (25 miles). The Leaburg hatchery manager on the McKenzie River found a tagged piece of wood (#1013) during a class field trip he was conducting in the summer of This log #1013 was 1.20 m (3.94 ft) long and 0.15 m (0.49 ft) in diameter and was deposited in an alder dominated riparian area directly below Leaburg dam on the McKenzie River. Although this is the longest documented movement of any piece of tagged wood from the Quartz Creek restoration project, other pieces may have moved greater distances. There is evidence that some pieces of wood from the Quartz Creek restoration site have been removed from the stream area. Aluminum tags used for tagging each log in Quartz Creek were found in blackened campfire pits along the Quartz Creek road. One log on the trash-rack was removed and presumably used for firewood as well. 62

65 Figure 19 a - b. Top: Looking downstream at full channel jam (Structure 19) at Quartz Creek, October, Bottom: Full channel jam (Structure 19) at Quartz Creek, October

66 Figure 19 c - d. Top: Full channel jam (Structure 19) at Quartz Creek, October Bottom: Full channel jam (Structure 19) at Quartz Creek, October

67 Figure 19 e - f. Top: Full channel jam (Structure 19) at Quartz Creek, October Bottom: Full channel jam (Structure 19) at Quartz Creek, October

68 Figure 20 a - b. Top: Proposed site for sill log structure at Quartz Creek, July Bottom: Same site with sill log structure installed, September Upstream sill log was partially moved by flood discharges in