SOME IMPACTS FROM THE USE OF A HOVERCRAFT ON THE ISKUT RIVER
ACKNOWLEDGEMENTS
Funding for the background research and field trip upon which this report is based was provided in large part by the Environmental Dispute Resolution Fund and West Coast Environmental Law Association. Project coordination was provided by the Board of Directors of Friends of theStikine Society, and field logistics were provided by Bill Sampson of Telegraph Creek, BC and by Dave Ellis of Petersburg, Alaska. Jean Ellis provided us with delicious meals. Patricia Houlihan of WCELA provided project assistance. To all of you I extend my sincere thanks.
G.F. Hartman Nanaimo, BC June 1996 Copyright, Friends of the Stikine Society, 1996 @ 1405 Doran Road North Vancouver, BC V7N 1K1 604-301-1238 - M. Paquet 604-323-9017 - P. Rowlands 604-985-4659 - M. Murray
TABLE OF CONTENTS
Acknowledgements ii
Introduction 1
Description of Field Work 1
Riparian Vegetation Removal 4
Removal of Large Woody Debris from the Iskut River 4
Travel of the AP.1-88 Hovercraft Over Shallow Side-Channels 6
Stranding of Fry by the Hovercraft 6
Scale of Loss of Fry 8
References 10
Appendix 1. Date, location, shore features, numbers and lengths of fish found 12
Photos 1-52 taken by G.F. Hartman during the period 3-8 May 1996 16-41
Figure 1. Map of area of field work 2
Table 1. Discharge in the Iskut River, May 1 to May 16, 1996 3
SOME IMPACTS FROM THE USE OF A HOVERCRAFT ON THE ISKUT RIVER
INTRODUCTION
Since 1990, there has been concern about the impacts arising from the operation of a hovercraft on the Iskut and Stikine rivers (Paquet 1995). The hovercraft, an AP.1-88 Hovercraft, has been used to service Cominco Ltd.'s Snip mine near Bronson Creek, a tributary of the Iskut River (Figure 1). In 1995, a review (Chilibeck 1995) was initiated with the primary objectives of determining "the extent, if any, to which the operation of the hovercraft CH-COM may: (a) constitute harmful alteration, disruption, or destruction of fish habitat in the Iskut River, BC, having regard to the definition of "fish habitat" as set out in the Fisheries Act, and (b) otherwise adversely affect fish in the Iskut River."
In this process, 26 documents were reviewed by T.J. Brown, on behalf of the Department of Fisheries and Oceans (DFO), and B. Lister, on behalf of Cominco Ltd. (Chilibeck 1995). After the review process was started, two additional reports (Sampson 1994, 1995a) were submitted and reviewed. Although the review commissioned by DFO called for examination of papers for evidence of destruction of fish habitat or adverse effects on fish, most of the reports in the list (Chilibeck 1995) did not contain studies that would demonstrate such effects. Reports by Sampson (1994, 1995a) and his videotapes demonstrated some of the problems. Sampson (1994, 1995a) documented erosion and collapse of river banks and made reference to fish being washed up on the river shore. Hay & Company (1995) reported hovercraft-induced erosion of the river banks at a lower rate than that found by Sampson (1994, 1995a).
The purpose of this study was to examine sites where destruction of riparian vegetation had been reported, to examine sites where alteration of fish habitat by snag removal operations had been recorded (Sampson 1995b), and to determine whether or not fish were being affected directly by the passage of the hovercraft.
DESCRIPTION OF FIELD WORK
Observations were made with regard to the following matters:
1. Riparian vegetation removal
2. Removal of large woody debris from the Iskut River
3. Travel of the AP.1-88 hovercraft over shallow side-channels
4. Stranding of fish by the hovercraft
The area in which field work was conducted is shown in the map in Figure 1 on the following page.
[This space contains a map of the Iskut obtained from the BC Ministry
of Forests Recreation Map of the Lower Stikine River. Map to be scanned
and placed into this document in the near future. In other words, hold
this space.]
Figure 1. Area in which field work took place, 2-8 May 1996, by G.F. Hartman and W.T. Sampson. The locations of camps are approximate. Observations were made from May 2 to May 8, 1996, between the Stikine-Iskut confluence and upriver on the Iskut River to the Verrett River (Figure 1) by Gordon F. Hartman and William Sampson, assisted on May 3 by David Ellis. Discharge in the Iskut River, May 1 to May 16, 1996, below Johnson River, ranged from 229.4m3/s to 362.5 m3/s (Table 1).
Table 1. Discharge in the Iskut River 1-16 May 1996. Data from Inland Waters Directorate, Nanaimo office. * indicates days when field work was performed.
Date - 1996 Discharge in m3/s
May 1 276.6
May 2 268.0*
May 3 266.1*
May 4 278.6*
May 5 306.5*
May 6 315.5*
May 7 282.7*
May 8 261.0*
May 9 250.5
May 10 236.2
May 11 229.4
May 12 233.7
May 13 245.4
May 14 253.2
May 15 310.2
May 16 362.5
Weather conditions between 2-8 May 1996 were dominated by a large high pressure area. It was mostly clear, almost entirely rain-free, but occasionally windy during the work. Locations where some observations were made were determined by use of Global Positioning equipment (Garmin GPS 55). Other locations were established in relation to major geographic features, such as tributary entrance points.
RIPARIAN VEGETATION REMOVAL
Sites where riparian trees were reported as being felled (Sampson 1995b) were visited and photographed. The felling of healthy, old-growth, streambank trees was listed as one part of the "snagging problem" carried out for Cominco Ltd. (Sampson 1995b). It was not possible to examine the entire riparian area along the Iskut River between its confluence with the Stikine River to the hovercraft launch site for removal of riparian vegetation. Standing cottonwood trees were felled at one location, and cottonwood and spruce were felled at another. At GPS coordinates 56-43.74 (N); 131-36.78 (W), three cottonwoods were cut down (photos 1 and 2). These trees all fell inward from the river. The stumps remained near the river edge. No jack marks were seen on the stumps. About 20 m from this location, one large cottonwood had fallen inland with its root mass attached (photo 3). The river bank had eroded from under this tree. The fact that this tree fell inward after erosion from under its root base indicates that there was no certainty that cottonwoods would fall toward the river and become a hazard even if the bank did erode away. Five cottonwoods and one spruce were felled at GPS coordinates 56-42.15 (N); 131-23.46 (W). The stumps from two of these trees are shown in photo 4. Four of the five trees fell inland. No jack marks were seen on the three stumps that were examined. It is unclear why these trees should have been considered a hazard.
DFO "did not object" to the removal of snags or overhanging trees (Von Finster 1993). However, it is clear that trees that were not "overhanging" were cut down. Presumably DFO would not have agreed to their being felled. The wording of Von Finster's letter (1993) also suggests that DFO may not have had the authority to permit cutting trees, but rather only exercised the option of not objecting.
We did not examine the whole shoreline for riparian cutting. The two above cases are presented as evidence that riparian trees were felled. I do not believe that eight out of nine of these were a "hazard," or they would not have fallen inland when cut. The cottonwood and spruce trees cut down were a part of the riparian environment. As such, they contributed to fish habitat.
REMOVAL OF LARGE WOODY DEBRIS FROM THE ISKUT RIVER
There was extensive evidence of cutting of instream large woody debris in the Iskut River. There were pieces of cut wood out on the floodplain, cut ends of trees in the river, blocks of cut trees along the river edge, and intensive debris removal at log jams. These things were evident at dozens of locations. However, in this report, I will describe four situations where larger amounts of woody debris were removed.
1. There was old evidence of removal of woody debris on the north side of a remnant island on the "Coho Overland" route. There were 32 cut ends visible in this one collection of woody debris. The end sizes ranged from 8 cm to 60 cm.
2. There was evidence of removal of woody debris from a debris pile between the "White Snag" log jam (GPS 56-43.8 (N); 131-34.73 (W)) and the "Hoodoo" log jam (GPS 56-42.81 (N); 131-26.96 (W)). There were 17 or more cut ends at this debris pile. Three logs were cut at the waterline.
3. The White Snag log jam (photo 5) once extended across the channel in which it was located (Sampson 1995b). During my visit (May 3 and 4, 1996), there were many cut ends (>30) at this log jam (photos 6, 7, and 8). It was not safe to walk on the jam and count cut ends on the right side of the channel. Much of the cutting at this site was done at or near water level (photos 6, 7, and 8). The material that was cut would have constituted fish habitat before it was removed. A much more detailed description of removal of woody debris at the White Snag log jam (Sampson 1995b) has been prepared and a copy was submitted to DFO. If the White Snag log jam extended across the river and blocked the passage of the hovercraft, it could not have been a "hazard." It was cut through in order to permit the route of the hovercraft to be changed, not to remove any danger that it presented.
The location where this woody debris removal has occurred is fish habitat. We sampled in the area where woody debris was cut and up to 30 metres downstream from it. We collected one chinook juvenile (90 mm) and one sculpin (92 mm) in the debris jam. We collected three chinook juveniles and one sculpin in the back-channel behind the debris jam (collection license CL96-05).
4. There were many cut ends (>30) at the Hoodoo log jam (photos 9, 10, and 11). A substantial amount of cutting has occurred at the Hoodoo log jam, with many pieces being cut at or near the water line (photos 12, 13, and 14). There was evidence of recent cutting at this location, e.g., fresh sawdust on some logs (photo 16). Many pieces of the cut material still remained floating in the jam (photos 14 and 15). There were cuts at and near the water line (photos 12 to 17). The material cut off would have constituted fish habitat. A more full description of alteration of the Hoodoo log jam is given by Sampson (1995b).
The locations where this woody debris removal occurred are fish habitat. We collected one juvenile chinook at the downstream side of the Hoodoo log jam (photo 17) and eight juvenile salmonids in woody debris in a channel not used by the hovercraft (photo 18). We sampled fish and caught two chinook (78 mm and 85 mm in size), one steelhead (145 mm), and one coho (65 mm). These fish were caught within the part of the jam that had cut ends in it.
Fish habitat has been altered and reduced by the "snag removal" work done in the White Snag and Hoodoo log jams. The GEE type minnow traps used would not have held the smaller fish -- 30 to 50 mm -- that were in the river, so our catches represent minimal numbers.
The snagging operations in the Iskut River were not authorised pursuant to section 35(2) of the federal Fisheries Act (Griggs 1996). They were carried out under conditions in which DFO "did not object." It is unclear to me how an agency can prosecute people for doing a particular thing under part of an Act, but agree to such inactivity "not pursuant" to such an Act. DFO was not prepared to authorise use of explosives to remove snags, or to allow heavy equipment to operate in the wetted perimeter of the river (Von Finster 1993). Cominco's concern about the fish may be indicated by their inclination to use explosives to remove woody debris and by their rationalisation of such action by use of unsupported statements about distribution of fish and DPW's use of the method (Elsdon 1993). It should be determined whether or not explosives were used to remove large woody debris. The amount of woody debris removed was not determined in the 2-8 May 1996 survey. It is, however, evident that sites that constituted good fish habitat were altered. DFO does not have any records of the numbers, location, or frequency of woody debris removed (Griggs 1996).
TRAVEL OF THE AP.1-88 HOVERCRAFT OVER SHALLOW SIDE-CHANNELS
The hovercraft travelled primarily along the main channel or major secondary channels where I observed it. Most fish that were found stranded (see next section) were located by such channels. However, in two cases, there was evidence that the hovercraft travelled over shallow side-channels (photos 19, 20, and 21). There were distinct grooves and ridges across the gravel bars and edges of the side-channels (photos 19 and 21). We saw fry in these channels (at locations 56-42.96 (N); 131-12.27 (W) and 56-41.53 (N); 131-06.94 (W)). Furthermore, the hovercraft did not always use the same route (photo 19). On May 5, 1996, about one kilometre upstream from the Craig River, the hovercraft travelled up through a small side-channel on one trip and, on May 6, 1996, through another larger channel on a second trip. If there is a regulatory requirement for the hovercraft to avoid shallow water, it is not always obeyed.
STRANDING OF FRY BY THE HOVERCRAFT
There were two reasons for examination of the river shore for stranded fry. Etherton (1994) found fry in the main channel of the Iskut River in sections used by the hovercraft. Etherton's data suggest there were fewer fish at main channel sites after the hovercraft had passed. Sampson (1994 and in videotape records) reports that fry were washed onto the beach by the hovercraft. Furthermore, the wake waves (B. Sampson videotape records) appear to have the potential to displace small, weak swimming fish up onto the shore. There are characteristics of the hovercraft wake waves and the beaches they cross that contribute to the stranding of small fish. The hovercraft creates a spray of water (photo 22) and a wake during and after its passage (photos 23 and 24). The spray clearly has the power to cast small fish onto the shore; we found evidence that this happened (photo 40). The wake wave occurs suddenly and strikes the shore almost directly (photo 23). These characteristics make wake waves quite different from natural wind-driven waves in the river. The waves produced in the wake of the hovercraft may travel many metres inward from the shore (photos 25 to 30). In some types of beach, part of the wave may be trapped as puddles (photo 25). In other beach areas, the waves may travel across wide stretches of sand (photo 27) or into small bays (photos 28 and 29). If the wake wave travels up a sand beach over a high point on the beach (photos 26 and 30) and then sinks into the sand, the risk of stranding fish may be high. In photo 31 a fry has been displaced and stranded on a beach where the water has percolated into the sand. Risk of stranding may also be high if there are depressions (photo 25) or coarse, loose gravel near the edge of the river. These considerations caused us to spend part of the field work time examining beach sections to see if fish were displaced onto the river shore.
At the sites of collections of large woody debris, e.g., Hoodoo log jam, the wake wave severely disrupted conditions along the edge of the jam (photo 32). It also passed through the debris, creating a strong surge in the water near shore. Beaches were examined in sections of channel where the hovercraft passed and in sections of channel that were not used by the hovercraft (photos 33 and 34). Search for stranded fry was carried out along 1,600 m of river shore, in channel sections where the hovercraft travelled, and in 2,200 m where it did not travel. Some sections of beach were examined several times. This was done in order to get information immediately before and after passage of the hovercraft. The total amount of shore examined, including such repeated searches of the same sections, was 3,000 m in sections used by the hovercraft and 3,275 m in sections not used by it.
Search of the shore was carried out by walking slowly and examining a two-to-three-metre strip of beach margin and any area adjacent to the shore that was depressed or appeared to be capable of isolating fry from the river. We turned sticks and stones over during this examination, however, we could not effectively examine sections where fry might be washed down among the deep, loose gravel and cobbles on the beach (photos 35 and 36). Immediately after wave passage in this type of location, fry would have a high probability of settling into the sand and remaining trapped. In such locations, they would be extremely difficult to find. Our counts of stranded fish on sandy sections (photo 37) that were easy to search, relative to those covered with loose gravel, may have been biased downward by bird-feeding activity. There were bird tracks (photo 38) present along the wave-wash lines at about one-quarter or more of the sections.
Invertebrates (photo 39) and small fish were found upon the beach. The invertebrates were not identified or counted. We found a total of 41 fish in the areas examined. Dates, times, locations, and abbreviated notes about the sites where fish were found are given in Appendix 1. The condition of fish found ranged from alive (L) to recently dead (D) to dried-out or decomposing (DD) (see Appendix 1). All of the fish found were in the sections of channel used by the hovercraft. We found no stranded fry in the sections not used by the hovercraft. Four of the fish found were sculpins, and 37 of them were salmon fry. Tentative identification indicated that the salmon fry stranded were sockeye, coho, and chinook. Twenty-one of the fish were found on sandy sections of shore, 15 were on sand-gravel-cobble sections, and 5 were found on gravel-cobble sections. Fish were found, on average, 6.46 m from the river's edge. The distances from the river's edge to where we found fry ranged from 1.2 m to 14 m. One fish was found 17 m from the edge of the river, but it may have been secondarily moved from an earlier location. The salmon fry and sculpins found were in various stages of decomposition (Appendix 1). Five were live or near dead, 11 were dead but not dry or decomposing, and 25 were dry or decomposing. The condition of one dead fry suggested that the hovercraft spray might displace and directly kill some fish. One fry was found dried out and stuck to the top of a stone (photo 40). I believe that this fish landed dead on the top of the stone and stayed there. A live wave-washed fish would have wiggled off the stone into the space beside it. At one site, 56-43.62 (N); 131-33.28 (W), we found fry in different stages of decomposition (photos 41 and 43). This indicated that fish were being stranded at different times there. Thirteen stranded fish were photographed (photos 40 to 51). In all but two instances, the fish were photographed where they were found, before they were moved. Eight fish, not photographed, were found at one location (photo 52). These fish appeared to have been swept out from around a small pile of woody debris (see right side of photograph for end of debris pile) through a low point in the beach, and then along a flat sand area for up to 17 m. Fish at the furthest point of travel were almost 10 m from shore in the shortest distance. These observations suggest that the waves that strand fish may, at some times, be very destructive.
There were four types of observations that caused me to conclude that the hovercraft caused the fish to be where we found them:
1. We found no fish in sections not used by the hovercraft.
2. I saw a salmon fry being tumbled back down the sand slope shore in the first or second wave after the hovercraft went by. This occurred at coordinates 56-44.03 (N); 131-37.44 (W). The beach had been dry, so a live fish could not have been resting there before the hovercraft passed.
3. We found a salmon fry stranded in a puddle after the hovercraft passed. The puddle had been examined carefully prior to the hovercraft passage and no fry were seen in it. A fry could not have survived in the dry puddle before the hovercraft came by. This fry was left in the puddle, which again became dry and uninhabitable for small fish. This occurred at coordinates 56-43.62 (N); 131-33.28 (W). We found another fry in another puddle with a clear wave-wash path to it. This fry would have perished as the puddle dried up.
4. On the sandy sections of shoreline where we found dead fry, all such fish were found within the part of the river shore where we could see wave-wash lines. In cases where we found very recently dead fry, in sections of shore that were covered with a mix of sand, gravel, and cobble, the fry were in locations that appeared to have been recently wetted.
In some types of shore sections, fish were extremely difficult to find. In two cases where we had seen fry in gravel-lined puddles, it took about five minutes to relocate them when the water level fell. In sections where there is deep loose gravel and cobble, it would be extremely difficult to find and enumerate stranded fry. Except on sandy sections of shoreline, I believe that we might find only one in one hundred fish. It is my opinion that the 41 fish we found indicate that very large numbers of small fish are stranded by the operation of the hovercraft.
SCALE OF LOSSES OF FRY
In this section I will try to provide some indication of scale of losses of fry. This task is difficult. Estimation of the numbers of fry stranded requires information on:
· numbers of fish found
· fraction of stranded fry that observers might actually find
· length of shore examined
· length of shore upon which fry may be stranded
· length of time a stranded fry would be available for location
· time period during which fry might be stranded by the hovercraft
The information and assumptions I will use to estimate losses are as follows:
A. In this study, 41 fish were found.
Regarding location effectiveness, I assumed one fish found for each 25 stranded in the area examined. This may be very conservative. Difficulty in finding fish that were known to be at a particular location, difficulty of seeing them among the small debris on the sand, the extreme difficulty of finding them among the gravel and cobble sections, and the likelihood that birds had eaten some of the fish that were stranded on the sand, governed this assumption.
B. I assumed that, on average, a fry would remain about five days before decomposing or being eaten by birds.
C. In this study, 1,600 metres of shore in channel sections where the hovercraft travelled were examined. The calculated length of shore in the Iskut River along which fry would be stranded was 41,660 metres. This was based on measurement of the amount of sand and gravel bar shoreline that bordered the main channel of the river from the mine to the confluence of the Iskut and Stikine rivers. Measurements were made with a map wheel on 1:15,000 scale air photos. This method is not precise, but it provides an indication of the length of shore involved. The air photos from which these measurements were taken were flown on July 19 and 31, 1992. Measurements were made on the following air photos:
30BCB-92060, #s 90 and 64
30BCB-92059, #s 143 and 167
30BCB-92064, #s 75, 77, 79, 81, 83, 195, 197, 198, 200, 201, 203, 218
Flows in the Iskut River on July 19 and 31, 1992, when the air photos were taken, were 1,110 m3/s and 978 m3/s, respectively. This was about three times greater than the flows during the May 2-8, 1996 period of the field trip, when they averaged 282.6 m3/s. During the relatively low flows of May 2-8, 1996, the area of exposed gravel and sand bars would be greater than it was during the period when the air photos were taken. Therefore, the length of river shore potentially available for stranding fish would have been greater than indicated by the measurements from the air photos. If I have erred in this regard, I believe that it is on the conservative side. During 1991, 1992, 1993, and 1996, after April 15, the durations of flows comparable to those that occurred when this survey was done, were 16, 16, 7, and 30 days, respectively. The estimated stranding of small fish during 1996 for a five-day period over 1,000 metres of shore is calculated as: 5/6 x 41 x 1000/1600 = 21.35 fish. Assuming we found one in 25 fish, this means that actual stranding was 539 fish per 1000 m of shore. From April 15 to May 15 (six 5-day periods), over 30,000 m of shoreline, stranding is estimated at 539 x 30 x 6 = 97,020 fish. During spring periods (when flow was about equal to when this study was done) after April 15 in 1991, 1992, and 1993, stranding is estimated at 52,920, 52,920, and 22,680, respectively. The durations in the August 1 to November 15 period in 1991, 1992, and 1993, when river flows and beach areas were comparable to those in this study, were 21, 46, and 25 days, respectively. I have made no extrapolation regarding late summer and autumn stranding. The estimates do not include losses during the autumn periods. The estimates of stranding during the spring periods are based on the assumption that stranding might occur along 30,000 m of shore rather than along 41,000 m. This reduction was made in case part of the measured length of gravel and sand bars contained wave-washed beaches that were too steep to permit stranding.
These estimates are based upon assumptions and rough calculations. This should be recognised. However, it should also be recognised that there are several assumptions that may be conservative. Regardless of any reasonable latitude on the estimates, they and the actual dead counts clearly indicate that there is a serious problem involving loss of salmon fry and small sculpins. It would be necessary to make extremely conservative assumptions to avoid concluding that the hovercraft is a danger to small fish. It should not be necessary to do more before action is taken.
REFERENCES
Chilibeck, B. 1995. Memo to M. Paquet re Fisheries scientific review,
Air cushion vehicle Iskut River, BC. June 21, 1995. 3 pp.
Elsdon, G.R. 1993. Memo to A. Von Finster, April 12, 1993. 1 page.
Etherton, P. 1994. Results of fish-capture activities at two sites
within the floodplain of the Iskut River, June 01-02, 1994. Report
prepared by P. Etherton, DFO, 122 Industrial Road, Whitehorse, YT. 29 pp.
Griggs, D. 1996. Memo to G.F. Hartman, June 2, 1996. 1 page.
Hay & Company, 1995. Natural and vessel-induced bank erosion, sediment
transport, and bed pressures of the lower Iskut River. Prepared for
Cominco Ltd., by Hay & Co. Consultants Inc., One West 7th Avenue,
Vancouver, BC V5Y 1L5. 33 pp plus figures and appendices.
Paquet, M. 1995. Memo to B. Chilibeck re Fisheries scientific
review/Cominco's hovercraft use on the Iskut River, July 4, 1995. 4 pp.
Sampson, W.T. 1994. Induced incremental erosion of the Iskut River
caused by the wake from an AP.1-88 hovercraft. Prepared by W.T. Sampson,
PO Box 98, Telegraph Creek, BC. 117 pp.
Sampson, W.T. 1995a. Summary Report on Cominco's Hovercraft. Presented
to the Tahltan Band Council and Lower Stikine Management Advisory
Committee, January 11, 1995. 53 pp.
Sampson, W.T. 1995b. The industrial removal of woody debris from the
Iskut River floodplain: 1990-1995. Prepared for Friends of the Stikine
Society, 1405 Doran Road, North Vancouver, BC V7K 1N1, by Bill Sampson. 29 pp.
Von Finster, A. 1993. Memo to Garth Elsdon, April 2, 1993. 1 page.
[This section is followed by Appendix 1: Dr. Hartman's notes on date, time, location, etc. of observations. That is subsequently followed by 26 pages of full-colour photos (52 photos). We have not had these scanned yet, but plan to scan about 10 and have them included in this document.]