6.3 SUBSTRATE COMPOSITION AND QUALITY

Transcription

1 6.3 SUBSTRATE COMPOSITION AND QUALITY METHODS The Wolman pebble count procedure (Wolman, 1954) is used to measure the diameter of the intermediate axis of 100 randomly selected stones along transects located in pool tailouts (Figure 6.7). Pool tailouts, areas where stream water typically downwells into the gravel bed, are targeted since these habitats are preferred spawning sites for chinook salmon and several other salmonids (Kondolf, 2000). The pebble count method is modified to target the low flow, wetted channel width rather than bankfull width, since monitoring interest is in substrate conditions during the spawning period. Sampling is performed each year in early August prior to spawning activity. The resulting data yield a size distribution for the bed surface deposits. Each pool tailout in Phases I through IV is sampled. The observer walks perpendicularly across the wetted width of the stream and back again, in the downstream direction, until a minimum of 100 pebbles have been randomly selected, measured, and recorded. Sizes smaller than 2 mm are classified as sand or silt using the texture by feel technique. preferred spawning site riffle riffle pool tailout pool FLOW water flow Figure 6.7. Illustration of a pool tailout, a preferred spawning area for chinook salmon. The lower surface water elevation of the downstream riffle creates a hydraulic gradient that causes the stream water to flow into the gravel bed, a phenomenon known as downwelling. Water flow brings dissolved oxygen into and removes metabolic wastes from redds (adapted from Kondolf, 2000). The following characteristics are calculated for each transect, per phase, and overall (Phases I-IV combined): percent fines ( 6.0 mm and 2.0 mm) D16 or range in sizes of the cumulative 16% D50 or range in sizes of the cumulative D84 or the range of sizes of the cumulative 84% percent of particles ranging from mm The pebble count data are then combined according to the standard Wentworth size classes (Table 6.4) and converted into percentages by size class. Data are graphed to illustrate percentage of total for each size class, dominant size class, and cumulative distribution. Comparisons are made to previous years and to performance criteria. Temporal changes in the proportion of fine sediments ( 2.0 mm and 6.0 mm) are assessed using chi-square contingency table analyses (Alldredge, 2000) EFFECTIVENESS M ONITORING R EPORT 95

2 C HAPTER 6 Table 6.4. Pebble measurements are placed into Wentworth size classes 1 and converted to percentages for producing cumulative size distribution curves. GENERAL DESCRIPTION PARTICLE SIZE CLASS MILLIMETER INCHES SILT/CLAY SILT/ CLAY <.062 <.0024 SAND SAND GRAVEL COBBLE BOULDER VERY FINE FINE FINE MEDIUM MEDIUM COARSE COARSE VERY COARSE VERY COARSE SMALL SMALL LARGE LARGE SMALL SMALL MEDIUM LARGE - VERY LARGE Several size classes are divided into two to describe channel substrate in finer detail PERFORMANCE CRITERIA Substrate characteristics are expected to exhibit an improving trend toward the following conditions, described as being preferred by salmonids or conducive to salmonid growth and survival: 1) Percent fines ( 6.0 mm) 2 (NWPPC, 1994). 2) Percent fines ( 2.0 mm) 14% [modified from the <1mm standard, described by Kondolf (2000), due to field methods that preclude differentiating between single particles less than 2 mm in size]. 3) Greater than of the substrate particles are within mm [preferred (movable) spawning substrate size range for chinook salmon and other native salmonids (Bjornn and Reiser, 1991; Jody Brostrom, IDFG Regional Fishery Biologist, personal communication, 2001] RESULTS Pool tailout transect locations are described per phase in Table 6.5 and depicted in Figure 6.8. Sampling occurred on August 8-10, 2000 and August 8-9, Post-restoration baseline (2000) substrate characteristics are compared to one-year post-restoration (2001). All but one transect in Phase IV were resampled in 2001, providing one-year comparisons of substrate conditions in 22 tailouts (Tables 6.6 and 6.7). Four new tailouts were identified and sampled in Table 6.8 and Table 6.9 summarize one-year changes in spawning substrate characteristics per phase and overall for Phases I IV combined. The number and percentage of transects meeting all three performance criteria in 2000 versus 2001 are compared in Table Particle size distribution curves, comparing 2000 and 2001 data, for each phase are illustrated in Figures Figure 6.13 illustrates the one-year change in particle size distribution for the entire project reach, Phases I IV. Differences in particle size distribution in 2001 among phases are depicted in Figure L OWER R ED R IVER M EADOW R ESTORATION P ROJECT

3 Table 6.5. Substrate monitoring transect locations and descriptions, Phases I IV, Lower Red River Meadow Restoration Project (see Figure 6.8). TRANSECT # DESCRIPTION PHASE I Transect 1 classic1 pool tailout; non-constructed reach; between XS 1 and XS 2 Transect 2 classic pool tailout; non-constructed reach; between XS 2 and XS 3 Transect 3 classic pool tailout; non-constructed reach; between XS 3 and XS 4 Transect 4 classic pool tailout; modified reach Two Sill Bend; approx. 32 feet downstream of rock sill in high flow channel Transect 5 classic pool tailout; modified reach Hopeful Barb Bend (1996); approx. 28 feet downstream of rock sill Transect 6 Non 2 -classic pool tailout; modified reach Hopeful Barb Bend (1996); approx. 8 feet downstream of lone barb in outside bank Transect 7 non-classic pool tailout; reshaped point bar No Touch Bend (1996); approx. 77 feet downstream of rock sill Transect 8 non-classic pool tailout; constructed reach Big Bend (1996); downstream of rock sill, approx feet upstream of XS 12 Transect 9 classic pool tailout; reconnected historic reach Goose Island Bend (1996); approx. 79 feet downstream of XS 12 Transect 10 classic pool tailout; reconnected historic reach Goose Island Bend (1996); approx. 68 feet downstream of XS 14, downstream of rock sill PHASE II Transect 1 Transect 2 (new in 2001) Transect 3 (#2 in 2000) Transect 4 (#3 in 2000) PHASE III Transect 1 Transect 2 Transect 3 Transect 4 Transect 5 non-classic pool tailout; constructed reach Giant Bend (1997); approx. 142 feet downstream of exclosure located between Ninety Degree Bend and Giant Bend Classic pool tailout; constructed reach Giant Bend (1997); approx. 60 feet downstream of XS 20 non-classic pool tailout; reconnected historic reach Loop 2 of Historic S-Curve Loops (1997); approx. 35 feet upstream of XS 24 classic pool tailout; reconnected historic reach Loop 3 of Historic S-Curve Loops (1997); approx. 26 feet downstream of XS 25 classic pool tailout; non-constructed reach; approx. 23 feet downstream from rock sill below Transition Bend classic pool tailout; reconnected historic reach Mirror Bend (1999); approx. 40 feet downstream of upstream edge of reinforced bank classic pool tailout; modified reach Inside Out Bend (1999); approx feet upstream of RP37 classic pool tailout; non-constructed reach; transect runs between RP 38 and LP 38 within Muddy Bend non-classic pool tailout; modified reach downstream of rock sill between Muddy Bend and High Bank Bend (1999); approx feet downstream of sill Transect 6 classic pool tailout; modified reach High Bank Bend (1999); approx. one foot upstream of XS 40 Transect 7 classic pool tailout; modified reach High Bank Bend (1999); approx feet upstream of first boulder in outside back riprap PHASE IV Transect 1 classic pool tailout; constructed reach Little Ponderosa Bend (2000); approx. 150 feet downstream (new in 2001) of XS 42 Old Transect 1 classic pool tailout; constructed reach Heeyey Bend (2000); approx. 44 feet upstream of XS 74 (sampled in 2000 no longer evident in 2001) Transect 2 classic pool tailout; reconnected historic reach Camas Bend (2000); approx. 38 feet downstream of XS 76 Transect 3 classic pool tailout; constructed reach tie into existing alignment at outside bank of Saaslaqs Bend (new in 2001) (2000); approx. 70 feet upstream of XS 48 Transect 4 classic pool tailout; non-constructed reach; 25 feet downstream of XS 48 at apex of Took-pon-wahwum Bend (new in 2001) Transect 5 classic pool tailout; non-constructed reach; transect runs between RP 49 and LP 49 within Took-ponwah-wum Bend 1 Classic pool tailout = well-defined pool with distinct riffle downstream similar to Figure Non-classic tailout = any configuration other than classic, for example, a pool followed by a run downstream, rather than a riffle (#3 in 2000) or pool area is s comparatively shallow, slow-moving stretch and not well-defined, but with a distinct riffle downstream EFFECTIVENESS M ONITORING R EPORT 97

4 C HAPTER LOWER RED RIVER MEADOW RESTORATION PROJECT Phases I - IV Red River Wildlife Management Area 2 PHASE IV old PHASE III PHASE II PHASE I Figure 6.8. Location of pool tailout transects, monitored for substrate composition and quality, in Phases I-IV, Lower Red River Meadow Restoration Project. 98 L OWER R ED R IVER M EADOW R ESTORATION P ROJECT

5 Table 6.6. Comparison of D16, D50, D84, and dominant size class characteristics of substrate sampled during the 2000 and 2001 field seasons, per transect in each of the four phases, Lower Red River Meadow Restoration Project. D16 (mm) D50 (mm) D84 (mm) Dominant Size (mm) TRANSECT # Phase I Transect Transect Transect Transect Transect Transect Transect Transect Transect Transect Phase II Transect Transect 2 n/a 4 n/a 20 n/a 38 n/a Transect Transect Phase III Transect Transect Transect Transect Transect Transect Transect Phase IV Transect 1 n/a 15 n/a 27 n/a 45 n/a Transect 1 ( old ) 2 n/a 4 n/a 28 n/a 2 n/a Transect Transect 3 n/a 20 n/a 43 n/a 68 n/a 33-48, Transect 4 n/a 20 n/a 42 n/a 70 n/a Transect n/a = no data available because pool tailout did not exist in the 2000 field season or pool tailout existed in 2000 but was no longer evident in EFFECTIVENESS M ONITORING R EPORT 99

6 C HAPTER 6 Table 6.7. Comparison of percent fines ( 2mm and 6mm) and percent suitable size of substrate sampled during 2000 and 2001 field seasons per transect in each of the four phases, Lower Red River Meadow Restoration Project. % Fines ( 2 mm) % Fines ( 6 mm) % Suitable Size ( mm) TRANSECT # Phase I Transect Transect Transect Transect Transect Transect Transect Transect Transect Transect Phase II Transect Transect 2 n/a 12 n/a 20 n/a 61 Transect Transect Phase III Transect Transect Transect Transect Transect Transect Transect Phase IV Transect 1 n/a 3 n/a 3 n/a 89 Transect 1 ( old ) 39 n/a 65 n/a 28 n/a Transect Transect 3 n/a 4 n/a 8 n/a 90 Transect 4 n/a 2 n/a 5 n/a 92 Transect n/a = no data available because pool tailout did not exist in the 2000 field season or pool tailout existed in 2000 but was no longer evident in L OWER R ED R IVER M EADOW R ESTORATION P ROJECT

7 Table 6.8. D16, D50, and D84 changes in spawning substrate by restoration phase and overall (Phases I-IV combined), Lower Red River Meadow Restoration Project. Data collected in 2000 represent the post-restoration baseline; data collected in 2001 are compared to 2000, documenting one-year post-restoration changes. CHANNEL D16 (mm) One-year D50 (mm) One-year D84 (mm) One-year REACH change change change Phase I none none decrease Phase II increase increase decrease Phase III increase decrease decrease Phase IV increase 6 30 increase increase Overall increase increase decrease 1 based on all particles sampled from 10 tailouts in both 2000 and based on all particles sampled from 3 tailouts in 2000 and 4 tailouts in based on all particles sampled from 7 tailouts in both 2000 and based on all particles sampled from 3 tailouts in 2000 and 5 tailouts in based on all particles sampled from 23 tailouts in 2000 and 26 tailouts in 20 Table 6.9. Percent fines ( 2 mm and 6 mm) and percent suitable size changes in spawning substrate by restoration phase and overall (Phases I-IV combined), Lower Red River Meadow Restoration Project. Data collected in 2000 represent the post-restoration baseline; data collected in 2001 are compared to 2000, documenting one-year post-restoration changes. CHANNEL % Fines ( 2 mm) One-year % Fines ( 6 mm) One-year % Suitable Size ( mm) One-year REACH change change change Phase I decrease decrease increase Phase II decrease decrease increase Phase III decrease decrease increase Phase IV decrease decrease increase Overall decrease decrease increase 1 proportion of fines below the 2 mm criterion significantly decreased (p < 0.05) in 2001 compared to 2000 for all phases combined and all individual phases, except Phase III. 2 proportion of fines below the 6 mm criterion significantly decreased (p < 0.05) in 2001 compared to 2000 for all phases combined and all individual phases. 3 based on all particles sampled from 10 tailouts in both 2000 and based on all particles sampled from 3 tailouts in 2000 and 4 tailouts in based on all particles sampled from 7 tailouts in both 2000 and based on all particles sampled from 3 tailouts in 2000 and 5 tailouts in based on all particles sampled from 23 tailouts in 2000 and 26 tailouts in 2001 Table Number and percent of total substrate transects that met all three performance criteria in year 2000 versus year 2001 per phase and overall, Lower Red River Meadow Restoration Project. TRANSECTS MEETING PERFORMANCE CRITERIA: Fines ( 6 mm) 2 Fines ( 2 mm) 14% Suitable Substrate ( mm) > CHANNEL REACH # % # % One-year change Phase I 4 of of none Phase II 1 of of 4 75 increase Phase III 5 of of 7 86 increase Phase IV 1 of of 5 80 increase Phases I-IV 11 of of increase EFFECTIVENESS M ONITORING R EPORT 101

8 C HAPTER 6 Substrate Particle Size Distribution, 2000 vs Phase I, Lower Red River Meadow Restoration Project % of Total 2001 % of Total 2000 Cum. % Finer 2001 Cum. % Finer Figure 6.9. Substrate particle size distribution for all pool tailouts combined in Phase I, Lower Red River Restoration Project, comparing 2000 and 2001 survey results. Substrate Particle Size Distribution, 2000 vs Phase II, Lower Red River Meadow Restoration Project % of Total 2001 % of Total 2000 Cum. % Finer 2001 Cum. % Finer Figure Substrate particle size distribution for all pool tailouts combined in Phase II, Lower Red River Restoration Project, comparing 2000 and 2001 survey results. 102 L OWER R ED R IVER M EADOW R ESTORATION P ROJECT

9 Substrate Particle Size Distribution, 2000 vs Phase III, Lower Red River Meadow Restoration Project % of Total 2001 % of Total 2000 Cum. % Finer 2001 Cum. % Finer Figure Substrate particle size distribution for all pool tailouts combined in Phase III, Lower Red River Restoration Project, comparing 2000 and 2001 survey results. Substrate Particle Size Distribution, 2000 vs Phase IV, Lower Red River Meadow Restoration Project % of Total 2001 % of Total 2000 Cum. % Finer 2001 Cum. % Finer Figure Substrate particle size distribution for all pool tailouts combined in Phase IV, Lower Red River Restoration Project, comparing 2000 and 2001 survey results EFFECTIVENESS M ONITORING R EPORT 103

10 C HAPTER Substrate Particle Size Distribution, 2000 vs Phases I-IV, Lower Red River Meadow Restoration Project 2000 % of Total 2001 % of Total 2000 Cum. % Finer 2001 Cum. % Finer Figure Substrate particle size distribution for all pool tailouts combined, Phases I IV, Lower Red River Restoration Project, comparing 2000 and 2001 survey results Substrate Particle Size Distribution Per Phase Lower Red River Meadow Restoration Project % of Total - Ph I % of Total - Ph II % of Total - Ph III % of Total - Ph IV Cum. % Finer - Ph I Cum. % Finer - Ph II Cum. % Finer - Ph III Cum. % Finer - Ph IV Figure Substrate particle size distribution for all pool tailouts, comparing 2001 substrate composition and quality among the four restoration phases, Lower Red River Restoration Project. 104 L OWER R ED R IVER M EADOW R ESTORATION P ROJECT

11 6.3.4 DISCUSSION Changes in D16, D50, and D84 (Table 6.8): Overall for Phases I-IV combined, both the D16 and the D50 increased from year 2000 to year 2001 (Figure 6.13). Phase III was the only reach that experienced a decrease in the D50 from 28 mm to 24 mm; however, this D50 is still within the preferred spawning size range ( mm) (Figure 6.11). Overall, the D84 decreased from 58 mm to 52 mm (Figure 6.13). Phase IV was the only reach experiencing an increase in the D84 from 43 mm to 58 mm. Sizes are within the preferred spawning size range (Figure 6.12). Changes in percent fines and suitable substrate size (Table 6.9): The proportion of fines below the 2 mm criterion significantly decreased (p<0.05) in 2001 compared to 2000 for all phases combined, from 20 to 12 percent (Figure 6.13), and for each individual phase, except Phase III. Phase III experienced a decrease from 8 to 7 percent (Figure 6.11). The proportion of fines below the 6 mm criterion significantly decreased (p<0.05) in 2001 compared to 2000 for all phases combined, from 28 to 18 percent (Figure 6.13), and for each individual phase (Figures ). In each phase and overall for Phases I-IV combined, percent suitable spawning size increased from year 2000 to Phase IV experienced the largest improvement from 40 to 76 percent. In 2001, Phase I contained the largest percentage of fines, 2 mm (16%) and 6 mm (24%), compared to the other three phases; Phase III contained the smallest percentages ( 2 mm equaled 7% and 6 mm equaled 12%) (Figure 6.14). Changes in transects meeting performance criteria (Table 6.10): The proportion of transects meeting all three performance criteria increased from year 2000 to year 2001 for all phases combined, from 48 to 65 percent, and in each individual phase except Phase I, which experienced no change. Proportion of transects meeting the criteria in 2001 ranged from 40 percent in Phase I to 86 percent in Phase III. Summary of Initial Trends: Although data represent only one year of change, initial trends in percent fines and percent suitable spawning size indicate a shift toward the established performance criteria. Future data collection and analysis are expected to document a continued improvement in spawning habitat as the channel adjusts toward equilibrium conditions as a result of restoration work. 6.4 SUMMER WATER TEMPERATURES METHODS Four Optic StowAway temperature loggers (accurate to ± 0.4 o F) are placed underwater in weighted, PVC pipe and located in protected, pool habitat areas to avoid surface temperature fluctuations, exposure to solar radiation, and physical damage. Loggers are situated at specific locations along the length of the lower meadow stream (Figure 6.15) to record the following water temperatures: Upstream End of Meadow = water entering off-site near meadow s upper boundary (Gibler Bridge). Upstream of Restoration Work = water entering project reach above restoration activities (XS4). Mid-Meadow Below Restoration Work = water exiting restored reaches (variable locations depending location of restoration work each field season). Downstream End of Meadow = water exiting lower meadow and entering canyon reach (Cole Porter Bridge) EFFECTIVENESS M ONITORING R EPORT 105