Sodom and Shearer Dam Removal Effectiveness Monitoring

Transcription

1 Sodom Dam Site: pre-removal Shearer Dam ( Sodom and Shearer Dam Removal Effectiveness Monitoring Sodom Dam Site: post-removal Final Report: OWEB Grant # February 1, 2013 Shearer Dam Site: pre-removal Prepared by: Desiree Tullos, Ph.D., PE Matt Cox Cara Walter Biological and Ecological Engineering Oregon State University 116 Gilmore Hall Corvallis, OR Shearer Dam Site: post-removal

2 Table of Contents List of Figures Introduction and Project Objectives Background and project objectives General site descriptions Methods Dispersed Sites Fish Habitat Temperature Intensive Sites Sodom Dam Shearer Dam Streamflow gauging Summary of Results Dispersed sites Temperature Temperature monitoring was used, in part, to investigate effects of potential ecological impacts of changes in the flow split. Lower flow in a reach may lead to warming due to lower volume of water Longitudinal temperature trends in Sodom Channel: Pre- and post-removal Fish Fish Cover Canopy cover Sreambank conditions Longitudinal profiles Vegetation Historical Calapooia In-channel wood Intensive sites

3 4.2.1 Sodom Dam Shearer Dam Discharge and flow splits Summary and future work Literature Cited Appendix A: Discharge gaging... Error! Bookmark not defined. Appendix B: Intensive site cross sections... Error! Bookmark not defined. Sodom Dam site... Error! Bookmark not defined. Shearer Dam site... Error! Bookmark not defined. Appendix C: Photo points... Error! Bookmark not defined. Appendix D: Visual Inspection Checklist Appendix E: Temperature monitoring locations on the Sodom Channel and Calapooia River. 84 3

4 List of Figures Figure 1: Site map, including extents of intensive monitoring sites and locations of dispersed sites. S1 and S2 sites are located in the Sodom channel and C1-C5 sites are all located on this historical Calapooia River. C0 and C6 is located on the mainstem Calapooia River Figure 2: The Sodom 1 dispersed site (map on left, photo on right). Site is located to the north of Linn West Drive, 2.5 km north of the bifurcation Figure 3: The Sodom 2 dispersed site (map on left, photo on right). Site is located directly to the north of Boston Mill Rd, 6.4 km north of the bifurcation... 9 Figure 4: The Calapooia 1 dispersed site (map on left, photo on right). Site is located east of I-5, 2.8 km downstream of the bifurcation Figure 5: The Calapooia 2 dispersed site (map on left, photo on right). Site is located alongside Roberts Rd, 6.35 km downstream of the bifurcation Figure 6: The Calapooia 3 dispersed site (map on left, photo on right). Site is downstream of the former location of Shearer Dam, 9.25 km downstream of the bifurcation Figure 7: The Calapooia 4 dispersed site (map on left, photo on right). The site is located just upstream of the confluence between the Calapooia and the millrace at Thompson s Mill State Historical Park, 12.2 km downstream of the bifurcation. The two red locations are approximate (GPS waypoints not taken due to lack of signal under dense vegetation) Figure 8: The Calapooia 5 dispersed site (map on left, photo on right). Site is located downstream of Thompson s Mill, km downstream of the bifurcation Figure 9: Pre-removal daily maximum temperatures collected in two Sodom Channel locations, 0.55km and 2.5km below the bifurcation in Sodom 1 corresponds to S1 in Figure Figure 10: Post removal daily maximum temperatures collected in 3 Sodom Channel dispersed site locations located at 0.55km, 2.5km and 6.4km below the bifurcation in Figure 11: Pre removal daily maximum temperatures observed at 5 dispersed sites in the Calapooia River in Calapooia 1- Calapooia 5 correspond to C1-C5 in Figure Figure 12: Post removal daily maximum temperatures observed at 2 dispersed sites and 1 winter temperature monitoring site in the Calapooia River after the removal of Sodom and Shearer Dams in These sites are located 4.1km, 6.35km and 12.2km downstream of the bifurcation Figure 13: The percent of native fish during the sampling period in 2010 and Figure 14: Breakdown of fish species, by location Figure 15: Fish cover changes in the Sodom Channel, 2010 to Figure 16: Fish cover changes in the Calapooia River, 2010 to Figure 17: Canopy cover measured at five units per site, on two dispersed sites along the Sodom Channel Figure 18: Canopy cover measured at five units per site, on five dispersed sites along the historical Calapooia River Figure 19: Channel longitudinal profiles at dispersed sites (S1 and S2) on the Sodom Channel.27 4

5 Figure 20: Channel longitudinal profiles measured in 2010 and 2012 at dispersed sites (C1-C5) on the Calapooia River Figure 22: Riparian vegetation observed at the Sodom 1 dispersed site in 2010 and Figure 23: Riparian vegetation observed at the Sodom 2 dispersed site in 2010 and Figure 24: Riparian vegetation observed at the Calapooia 1 dispersed site in 2010 and Figure 25: Riparian vegetation observed at the Calapooia 2 dispersed site in 2010 and Figure 26: Riparian vegetation observed at the Calapooia 3 dispersed site in 2010 and Figure 27: Riparian vegetation observed at the Calapooia 4 dispersed site in 2010 and Figure 28: Riparian vegetation observed at the Calapooia 5 dispersed site in 2010 and Figure 29: Volume of wood measured in Sodom Channel dispersed sites Figure 30: Volume of wood measured in Calapooia River dispersed sites. Note that the y axes vary in size, so that columns representing wood volume are not obscured due to scaling effects Figure 31: Longitudinal profile for Sodom Figure 32: Net change in area at cross sections in the area around Sodom Dam Figure 33: Longitudinal profile for the Calapooia River at Shearer Dam Figure 34: Net change in cross sectional area from as-built to 2012 for cross sections in the former Shearer Dam reservoir and downstream Figure 35: Calculated and measured discharge on the Calapooia River at Brownsville, the Calapooia River at Linn West Drive, and Sodom Channel at Linn West Drive Figure 36: Calculated discharge on the Calapooia River at Brownsville and Sodom Channel at Linn West Drive with the ratio of discharges for Sodom Channel at Linn West Drive and the Calapooia River at Linn West Drive relative to the Calapooia River at Brownsville Figure 37: Discharge on the Calapooia River at Brownsville Bridge... Error! Bookmark not defined. Figure 38: Rating Curve for the Calapooia River at Brownsville Error! Bookmark not defined. Figure 39: Discharge on Sodom Channel at Linn West Drive... Error! Bookmark not defined. Figure 40: Rating Curve for Sodom Channel at Linn West DriveError! Bookmark not defined. 5

6 1. Introduction and Project Objectives 1.1.Background and project objectives This report presents the results of geomorphic and biological monitoring around the removal of Sodom and Shearer dams on the Calapooia River and Sodom Channel. The overarching objectives od this effort were to 1) evaluate the effectiveness of the project in meeting objectives to inform maintenance and modification, and 2) investigate the spatial and temporal effects of the split flows, sediment dynamics, and channel reconfiguration associated with removing Sodom and Shearer Dams on habitat and fish of the Calapooia River. All data are disseminated via the project website : 2. General site descriptions The Calapooia River travels 121 km from its source in the Western Cascades before meeting the Willamette River near Albany, Oregon. Its drainage area of 947 km 2 consists of steep terrain managed for forestry in the upper watershed transitioning to low gradient agricultural and rural residential lands below the community of Holley (Runyon et. al 2004). The Calapooia is a winter rain-dominated system, with majority of annual runoff occurring from November to April. Average monthly flows at the Holley gauge (records from 1936 to 1990) ranged from 24.3 m 3 /s in January to 1.2 m 3 /s in August. The Sodom Channel was created in the 19 th century to divert flow for milling and to reduce flooding impacts in the lower Calapooia basin. The Channel leaves the main channel of Calapooia just downstream of RM 19, and carries the majority of the annual flow of the river. Sodom Dam was originally constructed in 1890 because the Channel had diverted the entire volume of the river. The most recent (concrete) Sodom Dam was constructed in the 1950s near the upstream end of the Sodom Channel in order to maintain flow in the historical Calapooia channel for use at Thompson s Mill (OPRD 2006). The dam measured 3.4m high and 25.9m wide (Calapooia Watershed Council, 2013). The pool behind Sodom Dam contained approximately 4600m 3 of sediment (Tetra Tech, 2008). Sodom Dam was removed in July of Various structures have historically been in place to divert water from the historical Calapooia channel near RM 23 into the millrace used by Thompson s Mill. The most recent concrete structure at Shearer Dam was built in 1956 at a location about 46 m below the millrace. This structure measured 2.2m high and 12.2m wide. Shearer Dam was removed in August of

7 Table 1: Characteristics of dispersed sites in the Sodom Channel (S1, S2) and Calapooia River (C1-C5). Site Name Dist DS of bifurcation (km) Low Flow Wetted Width (m) Top of Bank Width (m) Water Surface Slope S % S % C % C % C % C % C % 3. Methods Study design included both intensive monitoring at the sites of dam removal and at dispersed sites (Figure 1). Seven dispersed sites (2 in the Sodom Channel and 5 in the historical Calapooia) were selected to represent a sample of the entire system for detailed study of bank characteristics, habitat features and temperature (Figures 2-8). Goals and methods varied between the intensive and dispersed sites, as described in the following sections. 7

8 Figure 1: Site map, including extents of intensive monitoring sites and locations of dispersed sites. S1 and S2 sites are located in the Sodom channel and C1-C5 sites are all located on this historical Calapooia River. C0 and C6 is located on the mainstem Calapooia River. 8

9 Figure 2: The Sodom 1 dispersed site (map on left, photo on right). Site is located to the north of Linn West Drive, 2.5 km north of the bifurcation. Figure 3: The Sodom 2 dispersed site (map on left, photo on right). Site is located directly to the north of Boston Mill Rd, 6.4 km north of the bifurcation. 9

10 Figure 4: The Calapooia 1 dispersed site (map on left, photo on right). Site is located east of I-5, 2.8 km downstream of the bifurcation. Figure 5: The Calapooia 2 dispersed site (map on left, photo on right). Site is located alongside Roberts Rd, 6.35 km downstream of the bifurcation. 10

11 Figure 6: The Calapooia 3 dispersed site (map on left, photo on right). Site is downstream of the former location of Shearer Dam, 9.25 km downstream of the bifurcation. Figure 7: The Calapooia 4 dispersed site (map on left, photo on right). The site is located just upstream of the confluence between the Calapooia and the millrace at Thompson s Mill State Historical Park, 12.2 km downstream of the bifurcation. The two red locations are approximate (GPS waypoints not taken due to lack of signal under dense vegetation). 11

12 Figure 8: The Calapooia 5 dispersed site (map on left, photo on right). Site is located downstream of Thompson s Mill, km downstream of the bifurcation. 3.1 Dispersed Sites Fish Consistent with the surveys collected for pre-removal characterization and with USEPA s protocols for wadeable streams (Peck et al. 2006), fish sampling was performed by a contractor for this study using a backpack electroshocker and hand nets. Four of the dispersed sites were sampled annually (Figure 1): S2) Sodom Channel downstream of Boston Mill Road; C2) Calapooia River upstream of the mill, Shearer and Spillway Dams but downstream of I5; C4) Calapooia River upstream of the mill but downstream of Shearer and Spillway Dams; and C5) Calapooia River downstream of the mill but upstream of the confluence with Sodom Channel. This sampling supplements fish sampling being performed by the USEPA for a wider study upstream of Sodom Dam on the Calapooia River, and downstream of the Sodom Channel and Calapooia River confluence Habitat We evaluated changes in habitat at the seven dispersed sites on the Calapooia River and Sodom Channel. Each site consists of five contiguous transects, each of which are four activechannel widths long, as determined at the downstream end of the each site. Sites were sampled downstream to upstream. We modified USEPA s EMAP procedure (Kaufmann et al. 1999), as described below, to measure in-stream wood, canopy density, fish cover, thalweg depth, bed sediment, water surface velocity, channel width, slope, shade angle, and bank vegetation either along the transect or at cross sections situated at the midpoint of the transects. Along the transects, we sampled the following features: 12

13 Wood - All pieces in the active channel greater than 5 feet long or 0.5 feet in diameter were tallied. The positioning (in or out of water), stability (fixed or loose), and racking (individual or part of an accumulation) was documented for each piece of wood. In the case of larger accumulations, we estimated the overall dimensions and porosity (e.g. streamwise length, width, height, and volume filled with wood) as well as whether or not the accumulation was channel spanning or the dominant side of the channel if not channel-spanning. Vegetation Each bank was evaluated in two parts: downstream of the cross section and upstream of the cross section. For each part of the bank evaluated, the species or class of vegetation (vine, shrub, grass, mature tree) and percent of the bank covered by vegetation class were recorded. Bed slope and water depth - Water depth was measured with a stadia rod in the thalweg at an interval equal to the section length divided by 12. Bed slope was determined with a hand level and stadia rod for either half of each section or the whole section, depending on visibility. Substrate - Substrate was measured visually or with the bottom of the stadia rod (to differentiate sand and silt/clay) on the left, center and right of the wetted channel at four streamwise locations within each section: 1) the start; 2) ¼ of the length; 3) ½ of the length (at the cross section); 4) ¾ of the length. Percent embedded was visually estimated for substrate determined to be gravel and larger. At cross sections, we sampled the following features: Bank parameters - Bank slope in percent was determined by laying the stadia rod down with the clinometer on top of it for all discrete slopes (e.g. toe, bench, to terrace) along each bank. Bank material was identified as the dominant material and determined by pinching for fines or visual assessment for gravels or larger. Bank height was defined as the height above the water surface. Channel parameters - Velocity was estimated three times by extending the stadia rod to 13 feet, laying it streamwise on the surface of the water, and timing a dogwood leaf floating the length next to the rod. Channel width was measured from top-of-bank to topof-bank. Bottom width was measured as the wetted width. Shade angle was measured from the middle of the active channel looking up to the top of the vegetation on each side with the clinometer. Canopy Canopy density was measured four times at each cross section facing downstream, upstream, river right (oriented looking downstream), and river left using a densitometer with 17 intersections showing on the densiometer. The densiometer was 13

14 held level approximately one foot above the water surface, and each intersection that covered by vegetation was counted. Fish cover Perfect aerial coverage of ten types of potential fish cover was assessed in each unit of each site : Macrophytes, Large and small wood, live trees/roots, overhanging vegetation, undercut banks, boulders, artificial structures and bryophytes. We found no artificial structures or bryophytes at any of the dispersed sites. 3.2 Temperature Temperature was measured hourly at dispersed and intensive monitoring sites using ibutton sensors (model DS1921G). According to the manufacturer, these sensors are accurate to +/- 1 C and water resistant (IP 56). Additional water resistance was gained by placing the ibutton within two plastic layers and then within a sealed, galvanized pipe housing. The original sampling design called for three sensors at each dispersed site, placed at various depths to examine possible temperature stratification and locations of thermal refugia. In addition, sensors were placed above and below the intensive monitoring sites in order to understand the magnitude of heating enabled by the impoundment of flow behind the both dams. In the winter, a single sensor at each site was left in place, and in some cases moved to location that is accessible year round (e.g a nearby bridge abutment). Our experience with these particular sensors has been that they are very unreliable (Appendix F, Tables F1 and F2) when placed in a submerged environment for extended amounts of time. Even with a well-sealed case, water vapor caused unit failures in well over 60% of our placements overall. Thus, we were unable to complete the temperature analysis as originally envisioned. Longitudinal trends where simultaneous measurements do exist are presented here. 3.3 Intensive Sites Sodom Dam Spatial extent for the intensive monitoring near Sodom Dam is approximately 300 feet upstream of the bifurcation (River Design Group-RDG station 22+00) to 200 feet downstream on the historical Calapooia and 2000 feet downstream on Sodom Channel (RDG station 42+00). A combination of RTK GPS and total station field surveys were conducted annually at low water. Surveys were conducted as a longitudinal profile and cross sections at a) each engineered riffle crest, b) each pool that occurred between the engineered riffle structures, c) upstream of the bifurcation to Station 22+00, d) at the bifurcation, Station 26+00, e) downstream of the bifurcation in the historical Calapooia River (approximately 200 ). Additional survey points were collected in areas that greatly deviated from design both during the low flow survey, and soon after changes in the channel. Surveys at the completion of dam removal and channel construction, hereafter referred to as as-built surveys, were conducted by River Design Group (RDG). Subsequent surveys were conducted by the River lab at Oregon State University (OSU). 14

15 During summer baseflows, we completed a visual inspection checklist, developed by OPRD (See example, Appendix E), and field surveys of the following locations: engineered riffles, engineered log jams, vegetated soil lifts, channel reconstruction, specifically noting areas of erosion or deposition, and the bifurcation. Surveys and inspections specifically noted areas of sediment accumulation, discontinuous flow through coarse sediment that could lead to fish passage barriers, and lack of flow into either of the downstream channels. We revisited photo points during summer baseflow and for 1-2 storm events to document the performance of the structures during higher flows. Photos were taken at multiple angles per point. Locations established based on Federal Energy Regulatory Commission (FERC) permit requirements for effectiveness evaluation of the structures include: 2 photo points per engineered riffle: 1 looking upstream, 1 looking downstream 1 photo point per engineered log jam 1 photo point per vegetated soil lift at each associate engineered structure 5 Representative photo points for vegetative plantings 3 photo points at the bifurcation: 1) Looking downstream, 2) Looking upstream from Calapooia River below the bifurcation, and 3) Looking upstream from Sodom Channel below the bifurcation Shearer Dam Intensive monitoring around Shearer Dam extended from approximately 250 feet upstream of the Shearer Dam to 250 feet downstream. A combination of RTK GPS and total station field surveys were conducted at low water documenting the longitudinal profile and cross sections upstream and downstream of the Shearer Dam site. Surveys at the completion of dam removal and channel construction, hereafter referred to as as-built surveys, were conducted by RDG. Subsequent surveys were conducted by the River lab at Oregon State University (OSU). Photo points were established prior to dam removal at points of interest and were revisited during summer baseflow. 3.4 Streamflow gauging For the purpose of monitoring flow allocation between the two channels, two gages were utilized: 1. An existing OSU gauging station on the Calapooia River upstream of the bifurcation near Brownsville. Effort for this gage was focused on continuing to develop the rating curve, and downloading and processing flow data. 15

16 2. A new OSU gauging station on Sodom Channel at the Linn West Drive bridge. Effort for this telemetry-based gauging station was focused on extending the rating curve and providing hourly water level and discharge measurements to interested parties through a website. Discharge measurements on the Sodom Channel were subtracted from discharge on the Calapooia River to estimate flows through the historical Calapooia channel. On a time available basis, discharge measurements were also taken on the Calapooia River at Linn West Drive. All discharge measurements were taken according to USGS protocols (Rantz et al. 1982, Mueller et al. 2009) with a Price AA current meter either wading or using a crane from a bridge, or with a Teledyne RD Instruments StreamPro. Rating curves were developed using USGS protocols (Rantz et al. 1982, Kennedy et al. 1983, Kennedy et al. 1984). All data were published online at the project website: Rating curves and equations are presented in Appendix A. 4. Summary of Results 4.1 Dispersed sites Temperature Temperature monitoring was used, in part, to investigate effects of potential ecological impacts of changes in the flow split. Lower flow in a reach may lead to warming due to lower volume of water. Longitudinal temperature trends in Sodom Channel: Pre- and post-removal. Longitudinal trends are represented as the difference in maximum daily temperature between two sensors located in Sodom Channel. Due to damaged sensors, no pre-removal data is available from S2, which is located 6.4 km downstream of the bifurcation, but was functioning in 2012 for post-removal analysis. In addition, the upstream temperature sensor for the upstream Sodom Intensive site also failed. Thus, for the pre-removal condition, we compare (Figure 9) temperature from the sensors installed a) in the Sodom Intensive site, located 0.55 km downstream of the former dam site, to b) at the S1 dispersed site, located at Linn-West in the Sodom Channel, 2.5km downstream of the former dam site. From these data, we see no evidence of longitudinal trend in maximum daily temperature between the downstream Sodom Intensive monitoring site and S1 between early June and early July of

17 Figure 9: Pre-removal daily maximum temperatures collected in two Sodom Channel locations, 0.55km and 2.5km below the bifurcation in Sodom 1 corresponds to S1 in Figure 1. Comparing post removal temperature trends (Figure 10), daily maximum temperatures remain similar at the Sodom DS intensive and S1 sites. No evidence is seen of a longitudinal trend between the Sodom DS intensive and S1 sites, similar to pre removal observations. The daily maximum temperatures at the Sodom 2 site are occasionally cooler, but the relationships between the sites become less predictable after July 1 st. 17

18 Figure 10: Post removal daily maximum temperatures collected in 3 Sodom Channel dispersed site locations located at 0.55km, 2.5km and 6.4km below the bifurcation in Longitudinal temperature trends in the historical Calapooia River: Pre- and post-removal For the pre-removal condition (Figure 11), we compare daily maximum temperatures at 5 dispersed locations: 1) C1, located 2.8 km downstream of the bifurcation 2) C2, located 6.35 km downstream of the bifurcation 3) C3, located 9.3 km downstream of the bifurcation 4) C4, located 12.2 km downstream of the bifurcation, and 5) C5, located 13.3 km downstream of the bifurcation. Daily maximum temperatures do not show a consistent downstream warming pattern during this time period. In fact, maximum temperatures are generally cooler farther downstream from the bifurcation after June 15th. This may in part be due to the dense riparian shading in the historical Calapooia channel. It also appears that warmer water in the upstream of portion of this channel (e.g. C1) takes about one day to travel the 10.5 km to the farthest DS site (C5). This is most clearly apparent in the maximum on July 6 th, where temperature peaks at 23 C for the C1 location, but peaks at 21 C on July 7 th at C5. 18

19 Figure 11: Pre removal daily maximum temperatures observed at 5 dispersed sites in the Calapooia River in Calapooia 1- Calapooia 5 correspond to C1-C5 in Figure 1. For the post-removal condition (Figure 12), we examine daily maximum temperatures at three locations in the historical Calapooia channel. Due to sensor loss, data at C1, C3 and C5 are not available. However, data from a winter temperature monitoring location (Calapooia River at Linn West Drive 4.1km downstream of the bifurcation) were available and are included. Downstream cooling is observed in daily maximum temperature values between April 1 st and early June. One pattern observed is the reduction in daily maximum temperatures in the downstream direction. This pattern, observed post removal, is similar to the pattern observed prior to removal in

20 Figure 12: Post removal daily maximum temperatures observed at 2 dispersed sites and 1 winter temperature monitoring site in the Calapooia River after the removal of Sodom and Shearer Dams in These sites are located 4.1km, 6.35km and 12.2km downstream of the bifurcation. In summary, we conclude that effects of daily maximum temperature patterns from either changes in flow regime or changes in riparian condition are small and likely beyond our ability to detect with this dataset Fish Results of fish monitoring are presented as percent natives and community composition by sampling location. Nearly 100% of the fish observed in the dispersed sites were native in both survey periods for all sites (Figure 13). Species composition was dominated by torrent sculpin, reticulate sculpin, redside shiner and speckled dace (Figure 14). Smallmouth bass (a non-native species) were observed both in the historical Calapooia and the Sodom Channel. From these limited surveys, we see no evidence of impact on species distribution or % natives associated with the dam removals. 20

21 Figure 13: The percent of native fish during the sampling period in 2010 and 2012 Figure 14: Breakdown of fish species, by location. 21

22 4.1.3 Fish Cover Fish cover in the Sodom Channel underwent little change over the study period, with the exception of a reduction in overhanging vegetation observed at the S2 site. Filamentous algae declined in four of five historical Calapooia sites in Small woody debris also decreased at the same four sites. These changes likely represent the effects of increased flow in the historical Calapooia. No clear trends were observed in the presence of large woody debris or live trees in the channel. Figure 15: Fish cover changes in the Sodom Channel, 2010 to

23 Figure 16: Fish cover changes in the Calapooia River, 2010 to Canopy cover Along the Sodom Channel (Figure 17), canopy cover increased in four of the five units at the S1 site. Slight changes within units were observed at the S2 site, but overall, canopy cover was similar in 2010 and On the historical Calapooia channel, canopy cover (Figure 18) either remained similar (C2 and C3) or increased slightly (C1, C4, C5). Riparian disturbances large enough to reduce canopy cover were not observed at any of the dispersed sites. Figure 17: Canopy cover measured at five units per site, on two dispersed sites along the Sodom Channel. 23

24 Figure 18: Canopy cover measured at five units per site, on five dispersed sites along the historical Calapooia River. 24

25 4.1.5 Sreambank conditions Bank slopes changes were grouped into five discrete categories (Table 2). The accuracy of the clinometers is /- 5, so any change less than this is considered not measureable. Bank slope values were averaged when more than one measurement existed on the same bank. Channel width values were measured from the top of one bank to the top of the opposing bank. Table 2: Changes in bank slope, bank height, channel width following dam removal. Results are presented for individual cross sections in dispersed sites between 2010 and Slope change categories are represented as follows: >+15%(++), +5% to +15%(+), +5% to -5% (n.c. no change), -5% to -15%(-), >-15%(--). Channel width in the table represents the difference in top-of-bank width. Site Name Bank Slope Changes Average Change in Average Change in Channel Width at Top of Unit 1 Unit 2 Unit 3 Unit 4 Unit 5 Bank Height (m) Bank (m) S1 LB ++ n.c RB n.c S2 C1 LB LB n.c RB RB n.c n.c. n.c C2 LB n.c RB - -- n.c C3 LB RB n.c C4 LB ++ n.c RB n.c C5 LB n.c RB n.c Across the period (September 27 to October 15) of the 2010 survey, the estimated stage and discharge in the Sodom Channel were 0.4 m (1.3 ft) and 3.3 cms (115 cfs), respectively. On the historical Calapooia, estimated stage and discharge were 0.3 m (0.9 ft) and 1.5 cms (53 cfs), respectively. In 2012, our survey dates spanned fewer days (September 12-14) and flows were very different. Stage and discharge were both much lower, 0.3 ft (0.1 m) and 0.3 cms (9 cfs) respectively, in the Sodom Channel. In contrast, stage and discharge in the historical Calapooia were both higher that pre-project conditions, 0.4 m (1.3 ft) and 3.3 cms (115 cfs), respectively. In the Sodom Channel, channels appear to have mostly steepened, narrowed, and lowered between 2010 and The only exceptions to this trend are the right banks of S2, where slopes flattened by S1 and S2 sites are located 2.5 and 6.4 m, respectively downstream of the sites. However, without analysis of the streambank stability, we are unable to confirm that the extensive changes in bank width are associated with dam removal. For example, it is possible that some of the estimated changes in top widths are unreliable due to difficulty in identifying the top of bank in the heavily vegetated channels under different flow conditions. Analysis of 25

26 streambank stability across the study periods, to be completed, will provide addition insight into the reliability of these observations and the mechanisms for changes in streambank geometry. Along the historical Calapooia River, units both narrowed (C1, C2, and C5) and widened (C3, C4). Change in bank height was low for most units. Patterns in bank steepening are mixed; both C1 and C2 steepened on the left bank while the slope steepened on the right bank, suggesting erosion on the left bank. Most of the left and right banks at C3 either steepen or become flatten simultaneously. Most banks steepen at site C4, where the channel width increases substantially. The change in channel width and slope at C4 corresponds with an increase in wood volume (Figure 30). Alternating banks steepen and become less steep at site C Longitudinal profiles Along the Sodom Channel, the locations of pools dramatically shift between the two periods for both S1 and S2 sites (Figure 19). Because these sites are so far downstream (Table 1), it is unlikely that these changes are associated with the dam removal. Without additional information on the background, natural variability of the bed profile, we also cannot conclude whether changes are associated with the changes in winter flows (See Section 4.3, Table 3, and Figure 36 for pre- and post-project flow splits between the historical Calapooia and Sodom Channel). Thus, based on maximum GPS error (+/- 3m) in reoccupying former survey locations, we can only conclude that these large shifts in the locations of these pools on the Sodom Channel are not surveying artifacts but are legitimate channel changes that occurred across the study period. 26

27 Figure 19: Channel longitudinal profiles at dispersed sites (S1 and S2) on the Sodom Channel. Patterns of incision and aggradation varied across the dispersed sites on the historical Calapooia between the two study periods (Figure 20). One site (C1) incised, two sites aggraded (C3, C5), and two sites (C2, C4) experienced local erosion and deposition. It is possible that channel changes are a result of the flow split (See Section 4.3 for pre- and post-project flow splits between the historical Calapooia and Sodom Channel), but again, without some evidence of baseline variability at these sites, conclusions cannot be drawn. 27

28 28

29 Figure 20: Channel longitudinal profiles measured in 2010 and 2012 at dispersed sites on the Calapooia River. 29

30 4.1.7 Vegetation For the purposes of this report, vegetation data has been lumped into four broad categories (woody, shrubs, grass/forbs and bare). In general, grass and forbs were most prevalent in locations where small bank failures had recently exposed sediment to plant colonization. In reaches with more mature vegetation, the understory was so dense that very few areas of grass/forbs were observed. The most commonly observed wood species in our vegetation surveys were red osier dogwood (Cornus Stolonifera) and Oregon ash (Fraxinus Latifolia). The most commonly observed shrub species included Himalayan blackberry (Rubus Discolor), snowberry (Symphoricarpus Albus), and red flowering currant (Ribes Sanguineum). By far the most commonly occurring plant in the forb/grass category was reed canary grass (Phalaris Arundinacea). Along the Sodom Channel, the presence of forbs decreased between 2010 and 2012 (Figure 22) for most units in S1 and S2. More woody vegetation was observed on the left bank at S1, while less was observed on the right bank, where woody vegetation was replaced primarily by shrubs. At S2, woody vegetation comprised more of the bank vegetation in 2012 than in Percent of the bank with no vegetation was lower in 2012 that 2010 for nearly all units in S1 and S2, replaced by a mixture of woody and shrubby vegetation. Figure 21: Riparian vegetation observed at the S1 dispersed site. 30

31 Figure 22: Riparian vegetation observed at the S2 dispersed site. Historical Calapooia Across most of the dispersed sites on the historical Calapooia, bare areas observed in 2010 were not present in 2012 (Figures 23-27). Grass and forbs were also reduced, with a few exceptions (C1, Unit 1, right bank; C5, Unit 1, right bank; C5, Unit 5, left bank). For these units where grasses and forbs were not lower in 2012, the opposite bank became much less steep and the bank where the grass/forbs were observed became steeper. This is consistent with initial observations in these units that area of bank failure tended to be colonized with reed canary grass. For many areas in C3, C4 and C5 (Figures 25-27), it appears that woody vegetation was replaced by shrubs in However, we do not believe this shift actually occurred. Instead, we believe the difference may be related to a classification discrepancy; Field technicians classified red osier dogwood as woody in 2010 and as a shrub in The banks of these sites are heavily overgrown, with very little undergrowth. 31

32 Figure 23: Riparian vegetation observed at the C1 dispersed site. Figure 24: Riparian vegetation observed at the C2 dispersed site. 32

33 Figure 25: Riparian vegetation observed at the C3 dispersed site. Figure 26: Riparian vegetation observed at the C4 dispersed site. 33

34 Figure 27: Riparian vegetation observed at the C5 dispersed site In-channel wood Very little wood was present at either of the dispersed sites on the Sodom Channel in 2010 and 2012 (Figure 28). At S2, one somewhat large accumulation (10 m 3 in Unit 4 of was associated with one large fallen tree. Figure 28: Volume of wood measured in Sodom Channel dispersed sites. Much more wood was observed in the historical Calapooia (Figure 29) than in the Sodom Channel, and the volume of wood varied more in the historical Calapooia than in the Sodom Channel between the two study periods. Both the import of smaller pieces of wood and the 34

35 export of both large individual pieces of wood and accumulations account for the differences between study periods, and indicate that wood movement was active in the historical Calapooia channel post dam removal. For example, several sites (C1, C3 and C5) had greater accumulation of wood in 2012 than in with 2010 (Figure 29). This increase in wood volume consisted mainly of numerous smaller pieces of wood. Both C2 and C4 lost wood between 2010 and 2012: Site C2 had a single large single piece of wood present in 2010 that was not present in 2012, while a large wood accumulation present in C4 in 2010 was not observed in However, wood volumes in the other units of C2 were similar or lower in 2012 than in 2010, while wood volume in C4 increased wood volume in the remaining four units by Figure 29: Volume of wood measured in Calapooia River dispersed sites. Note that the scales on the y-axes are not consistent. 35

36 4.2 Intensive sites Sodom Dam As can be seen from the longitudinal profile (Figure 30), change in channel area (Figure 31), and cross sections (Appendix C), the Sodom Channel above, within, and downstream of the influence of Sodom Dam greatly changed as a result of the channel reconstruction (pre-removal June 2011 to as-built November 2011), and from the changes in flows during the 2012 water year (as-built to post-removal June/July 2012). A maximum of approximately 10 feet of erosion occurred between the as-built and the June/July 2012 surveys for the pool (3300 m) above the former dam site. In contrast, the historical Calapooia River underwent few changes at the cross section 200 feet downstream of the bifurcation (Figure 31). There was little net change for cross sections outside of the reconstructed area, although the most upstream cross section at station changed in shape with a ~50 shift toward river right of a mid-channel bar (Appendix C). In cross-section, there were dramatic changes upstream of and within the middle riffle of the reconstructed area, starting at cross sections at and continuing through (Appendix C). At its maximum, the river right bank retreated 60 feet and the bed lowered up to 15 feet, resulting in erosion of a total volume of approximately 5,000 cubic yards of material. There were also moderate changes in the river left bank within the most upstream riffle between cross sections at and 30+40, including creation of a backwater channel and natural log jam. At the cross section at within the upstream riffle, the backwater channel visible in the 2012 survey appears to be a reversion to the pre-removal bed elevation for that cross section. In addition to the changes highlighted from the channel surveys, we identified several changes in 2012 relative to the as-built condition from the visual inspection (Appendix E) of the engineered riffles, log jams, and vegetated soil lifts. The primary change visually noted at the engineered riffles was the exposure of the large blocks of rocks making up the ribs for each riffle. The ribs were exposed for all three riffles: primarily on the banks for the middle and downstream riffles, and across the entire channel for the most upstream riffle. For the engineered log jams, all structures remained largely intact. We observed small amounts of upstream sediment accumulation at the most downstream river left and most upstream river right jams. Moderate amounts of erosion occurred upstream and adjacent to the other two river left jams and the river right jam immediately upstream of the bank failure, between and cross sections. Finally, five of the nine vegetated soil lift were completely intact and growing. Approximately 1/3 to all of the structure s length washed away from the remaining four lifts. 36

37 Figure 30: Longitudinal profile for Sodom Channel. Figure 31: Change in area at cross sections in the area around Sodom Dam. Positive values represent deposition and negative values represent erosion. 37

38 4.2.2 Shearer Dam There were few changes in the bed and banks of the former Shearer Dam reservoir area and immediately downstream between the as-builts and 2012 surveys (Figure 32, Appendix C). The largest changes in cross sectional area were on the river left bank of cross sections at and directly adjacent to the former dam location (Figure 33). Figure 32: Longitudinal profile for the Calapooia River at Shearer Dam Figure 33: Net change in cross sectional area from as-built to 2012 for cross sections in the former Shearer Dam reservoir and downstream 38

39 4.3 Discharge and flow splits The project sites experienced several moderately-sized storm events over the study period (Figure 35). Unfortunately, the range of the pressure transducer installed at Sodom Channel at Linn West Drive was insufficient to capture the peak for several storms as indicated by the dashed line in Figure 34. Thus, discharges above the dashed gray line was estimated based on relationships with nearby USGS-gaged streams (Mohawk River near Springfield: , South Santiam below Cascadia: ). However, we also note that peaks above the range of the pressure transducer were primarily those that overtopped banks upstream and downstream of the gaging station and therefore difficult to accurately capture anyway. Prior to project implementation, the gaging station at Sodom Channel at Linn West Drive captured several storm events, including the annual peak. We estimate that this event has a recurrence interval of 1.6 to 3.4 years. After the project, similarly sized and larger events occurred. The largest event in January of 2012, with a recurrence interval estimated to be between 1.8 and 5.6 years. The split of flow between the historical Calapooia River and Sodom Channel was highly unequal prior to the dam removal and did not appear to vary with discharge (Table 3, Figure 36). Post-project ratios varied more with discharge, such that more flow was conveyed down the historical Calapooia during moderate discharges (e.g. 12/22/11) and less flow was conveyed down the historical as discharge increased (Table 2). Thus, more higher flow events were conveyed down the historical Calapooia in 2012, both because 2012 was a wetter year and because the historical Calapooia conveys relatively more of the moderate flows than pre-project. Table 3. Percent of Brownsville flows that are conveyed down historical Calapooia River. Note that ratios are relative; At higher flows, more tributaries are activated and thus the flows at the Brownsville gage become less representative of flows just above the bifurcation. Results are sorted in increasing values of flow at Brownsville. Date Historical Calapooia at Linn West (cfs) Brownsville (cfs) Percent of Brownsville flow in historical Calapooia 2/8/ /8/ /7/ /18/ /16/ /22/ /4/ /24/ /22/ /22/

40 Figure 34: Calculated and measured discharge on the Calapooia River at Brownsville, the Calapooia River at Linn West Drive, and Sodom Channel at Linn West Drive. 40

41 Figure 35: Calculated discharge on the Calapooia River at Brownsville and Sodom Channel at Linn West Drive. The ratio of discharges for Sodom Channel at Linn West Drive and the Calapooia River at Linn West Drive relative to the Calapooia River at Brownsville are presented on the secondary y-axis. 5. Summary and future work The removal of Sodom and Shearer dams appears to have limited effects on the channel morphology or ecological of the Calapooia River system. The most obvious effects are those on the flow split; more of the low and moderate flows are conveyed through the historical Calapooia River (Figure 36, Table 3). Some morphological changes were observed, including variability in the longitudinal profiles (Figures 19 and 20) and streambank conditions (Table 2), but could not be conclusively linked to the dam removals or changes in flow splits. No clear evidence of effect from the projects on temperature, vegetation, fish, or various features of the channel habitat was observed. Further analysis, underway, is needed to a) link streambank changes to veg changes, and b) characterize streambank stability, using the USDA s Bank Stability and Toe Erosion Model (BSTEM) model, to identify mechanisms for observed changes in streambank geometry. 41

42 6. Literature Cited Calapooia Watershed Council Sodom Shearer Dams Fish Passage Improvement and Flow Management. Accessed January 17, Kaufmann, P.R, P. Levine, E.G. Robison, C. Seeliger, and D.V. Peck Quantifying Physical Habitat in Wadeable Streams. EPA/620/R-99/003. U.S. Environmental Protection Agency, Washington, D.C. Kennedy, E. J Computation of Continuous Records of streamflow. Techniques of Water- Resources Investigations of the United States Geological Society Chapter A13. Kennedy, E. J Discharge Ratings at Gaging Stations. Techniques of Water-Resources Investigations of the United States Geological Society Chapter A10. Mueller, David S., and Wagner, Chad R Measuring Discharge with Acoustic Doppler Current Profilers from a Moving Boat. U.S. Geological Survey Techniques and Methods 3A- 22. Oregon Parks and Recreation Department (OPRD) Thompson s Mills State Heritage Site, Master Plan. Peck, D. V., A. T. Herlihy, B. H. Hill, R. M. Hughes, P. R. Kaufmann, D. J. Klemm, J. M. Lazorchak, F. H. Mc Cormick, S. A. Peterson, P. L. Ringold, T. Magee, and M. R. Cappaert Environmental Monitoring and Assessment Program: Surface Waters Western Pilot Study-field operations manual for wadeable streams. EPA 620/R-06/003. US Environmental Protection Agency, Washington, DC. Rantz, S.E. and others, Measurement and Computation of Streamflow: Volume 1. Measurement of Stage and Discharge. Geological Survey Water Supply Paper Runyon J, Andrus C, Schwindt R Calapooia River Watershed Assessment. Calapooia Watershed Council: Brownsville, OR. Tetra Tech Preliminary Assessment and Conceptual Site Model: Sodom Dam Conversion Project, Calapooia River/Sodom Channel. Linn Country, OR. Prepared for Oregon Parks and Recreation Department and the Army Corps of Engineers. 42