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TURBIDITY and THE EFFECT OF SCALE

TURBIDITY and THE EFFECT OF SCALE. Joseph C. Greene, Research Biologist Claudia J. Wise, Physical Scientist. Flood Stage, Klamath River above Portuguese Creek, 2005.

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TURBIDITY and THE EFFECT OF SCALE

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  1. TURBIDITY and THE EFFECT OF SCALE Joseph C. Greene, Research Biologist Claudia J. Wise, Physical Scientist

  2. Flood Stage, Klamath River above Portuguese Creek, 2005 “Mining debris is chemically inert, makes no oxygen demand on the stream and therefore takes away from the flowing water nothing which the fish require. This is equally true of this material whether placed in transit by nature or by man since the products are alike in nature and comes from the same sources…” Swartley, A. M. Appendix A. In: Ward, H. B. 1938. Placer Mining on the Rogue River, Oregon, in Its Relation to the Fish and Fishing in that Stream. Department of Geology and Mineral Industries, State of Oregon, Portland, OR

  3. Klamath River water: The left vial was allowed to settled for 24-hours, the right vial was shaken to re-suspend the particulates. The sample was measured at 656 NTU.

  4. Cross-sectional measurements of turbidity at various distances downstream from an 8-inch suction dredge in the Fortymile River, Alaska. The dredge was operating approximately 7 m from the right bank at the time of sample collection. 16 ft. 33 ft. 66 ft. 1,050 ft. Royer et al,,1999. Impact of Suction Dredging on Water Quality, Benthic Habitat, and Biota in Fortymile River, US EPA Final Report.

  5. Unfiltered concentrations of copper and zinc measured in the Fortymile River, AK collected at locations upstream of the 8-inch dredge; the dredge was located at zero on the x-axis. 131 ft 131 ft 263 ft. 394 ft. Royer et al,,1999. Impact of Suction Dredging on Water Quality, Benthic Habitat, and Biota in Fortymile River, US EPA Final Report.

  6. Temperature of the Sacramento River is of concern for the well-being of migrating fish such as salmon. The concentrations of trace elements, including mercury, were always below any existing drinking water standards. Mercury concentrations frequently exceeded the standards for the protection of aquatic life, and the exceedances always happened during the late fall to early spring rainy season. Domagalski, J. L., and Peter D. Dileanis, 2000. Water-Quality Assessment of the Sacramento River Basin, California – Water Quality of Fixed Sites, 1996-1998, U.S. GEOLOGICAL SURVEY, Water-Resources Investigations Report 00-4247

  7. Natural levels of turbidity may be higher than levels of turbidity caused by suction dredging during certain times of the year Effects of the levels of turbidity and suspended sediment normally associated with suction dredging appear less than significant with regard to the health or physiology of adult and juvenile salmonids

  8. Research to Support the Siskiyou National Forest DEIR The SNF engaged Dr. Peter B. Bayley, Dept. Fisheries & Wildlife, Oregon State University, to conduct a “Cumulative Effects Analysis” on the effects of suction dredging forest-wide Dr. Bayley concluded: "The statistical analyses did notindicate that suction dredge mining has no effect on the three responses measured, but ratherany effect that may exist could not be detected at the commonly used Type I error rate of 0.05." (In other words, if there are effects, they are so smallthey can't be measured.) Bayley, P.B., 2003, Response of fish to cumulative effects of suction dredge and hydraulic mining in the Illinois subbasin, Siskiyou National Forest, Oregon, Dept. Fisheries & Wildlife, Oregon State University, Corvallis OR 97330

  9. Dr. Bayley continued… "The reader is reminded of the effect of scale. Localized, short-term effects of suction dredge mining have been documented in a qualitative sense. However, on the scales occupied by fish populations such local disturbances would need a strong cumulative intensity of many operations to have a measurable effect." Bayley, P.B., 2003, Response of fish to cumulative effects of suction dredge and hydraulic mining in the Illinois subbasin, Siskiyou National Forest, Oregon, Dept. Fisheries & Wildlife, Oregon State University, Corvallis OR 97330

  10. THE ROGUE RIVER AS IT FLOWS PAST THE GRANTS PASS, OREGON, SEWAGE TREATMENT PLANT, MAY 10, 2005. ACCORDING TO THE GRANTS PASS DAILY COURIER, TURBIDITY IN THE RIVER DUE TO RECENT RAINS MEASURED AT APPROXIMATELY 54-61 NTUs. APPROXIMATE SIZE OF A 4” SUCTION DREDGE

  11. A report from the Siskiyou National Forest answered the question, “How much material is moved by annual mining suction dredge activities and how much does this figure compare with the natural movement of such materials by surface erosion and mass movement?” The movement rate by suction dredge mining would equal about 0.7% of natural rates. Cooley, M.F. 1995. Forest Service yardage Estimate. U.S. Department of Agriculture, U.S. Forest Service, Siskiyou National Forest, Grants Pass, OR. The total acreage of all analyzed claims related to the total acres of watershed is about 0.2 percent. The percentage of land area within riparian zones on the Siskiyou National Forest occupied by mining claims is estimated to be only 0.1 percent. SNF, 2001. Siskiyou National Forest, Draft Environmental Impact Statement: Suction Dredging Activities. U.S. Department of Agriculture, U.S. Forest Service, Siskiyou National Forest, Medford, OR. The area or length of river or streambed worked by a single suction dredger, as compared to total river length, is relatively small compared to the total available area. CDFG, 1997. draft Environmental Impact Report: Adoption of Amended Regulations for Suction Dredge Mining. State of California, The Resource Agency, Department of Fish and Game

  12. CONCLUSION Small-scale gold suction dredging temporarily effects a very small area in the environment relative to the entire area in which all dredges operate.

  13. Salmon River Dredge Pit and Spoils Survey 260 ft 10/13=76.9% Leroy Cyr, Fish Biologist, 2005, Interoffice Memorandum to Jerry Boberg, Fish and Watershed Program Manager, Six Rivers National Forest.

  14. Leroy Cyr, Fish Biologist, 2005, Interoffice Memorandum to Jerry Boberg, Fish and Watershed Program Manager, Six Rivers National Forest. 442 ft 11/26=42.3%

  15. Leroy Cyr, Fish Biologist, 2005, Interoffice Memorandum to Jerry Boberg, Fish and Watershed Program Manager, Six Rivers National Forest. 364 ft 6/14=42.9%

  16. Salmon River Study Conclusions • Measured dredge holes cover a total length of 1,066 ft. The entire 79 miles of the Salmon River covers a length of 417,120 linear feet. Therefore, suction dredge holes disturbed 0.26% of the area, calculated on a linear basis. • The length of the dredge holes is actually <0.26% because the data does not allow for calculation of area disturbed vs linear area disturbed. The total dredge hole area of the Salmon River is less than that calculated because the dredge holes did not extend to both margins of the river.

  17. Salmon River Study Conclusions Refugia has been defined, in the literature, as any hole in a river bottom that is 3 feet or deeper. This study identified 27 potential refugia created by suction dredging. All of the suction dredge holes disturbed <0.26% of the river bottom. 27 of the 53 holes dredged, or 51%, have the potential of improved habitat for the survival of species in the Salmon River.

  18. Positive Effects of Suction Dredging Excavations from dredging operations can result in temporarily formed pools or deepen existing pools which may improve fish habitat. Deep scour may intersect subsurface flow creating pockets of cool water during summer which can provide important habitat for fish. Nielsen, J. L., T. E. Lisle, and V Ozaki. 1994. Thermally stratified pools and their use by steelhead in northern California streams. Trans. Am. Fish. Soc. 123:613-626. During times of low flow in a river or stream, increased water depth can provide a refuge from predation by birds and mammals Harvey, B. C., and A. J. Stewart. 1991. Fish size and habitat depth relationships in headwater streams. Oecologia. 87:336‐342. Pools created by abandoned dredger sites can provide holding and resting areas for juvenile and adult salmonids. Stern, G. R. 1988. Effects of suction dredge mining on anadromous salmonid habitat in Canyon Creek, Trinity County, California. M.S. Thesis, Humboldt State University, Arcata, California, 80 pp.

  19. CUMULATIVE EFFECT OF MULTIPLE DREDGE OPERATIONS “No additive effects were detected on the Yuba River from 40 active dredges on a 6.8 mile stretch”. Harvey, B.C., K. McCleneghan, J.D. Linn, and C.L. Langley, 1982. Some physical and biological effects of suction dredge mining. Lab Report No. 82-3. California Department of Fish and Game. Sacramento, CA. “Six small dredges (<6 inch nozzle) on a 1.2 mile stretch had no additive effect Harvey, B.C. 1986. Effects of suction gold dredging on fish and invertebrates in two California streams. North American Journal of Fisheries Management 6:401-409. The Chugach National Forest, Alaska found that, “The results from water quality sampling do not indicate any strong cumulative effects from multiple placer mining operations within the sampled drainages.” “Several suction dredges probably operated simultaneously on the same drainage, but did not affect water quality as evidenced by above and below water sample results. Huber and Blanchet, 1992. Water quality cumulative effects of placer mining on the Chugach National Forest, Kenai Peninsula, 1988-1990. Chugach National Forest, U.S. Forest Service, Alaska Region, U.S. Department of Agriculture.

  20. In the recreational mining area of Resurrection Creek, five and six dredges would be operating and not produce any water quality changes. Huber and Blanchet, 1992. Water quality cumulative effects of placer mining on the Chugach National Forest, Kenai Peninsula, 1988-1990. Chugach National Forest, U.S. Forest Service, Alaska Region, U.S. Department of Agriculture. “Department regulations do not currently limit dredger densities but the activity itself is somewhat self-regulating. Suction dredge operators must space themselves apart from each other to avoid working in the turbidity plume of the next operator working upstream. Suction Dredging requires relatively clear water to successfully harvest gold. CDFG, 1997. draft Environmental Impact Report: Adoption of Amended Regulations for Suction Dredge Mining. State of California, The Resource Agency, Department of Fish and Game

  21. The streams in Alaska have tremendous populations of char, Arctic Grayling, and various species of salmon. • The environment that sustains these native populations has had intense suction dredging activities that have been ongoing for decades. • Other problems must be more detrimental to fish and their freshwater habitat.

  22. Harvey and Lisle “measured scour of Chinook salmon redds on dredge tailings and natural substrates in Elk Creek, South Fork Salmon River, and Scott River, California.” They “measured maximum scour with scour chains and net scour by surveying before and after high winter flows. Scour of chinook salmon redds located on dredge tailings exceeded scour of redds on natural substrates, although the difference varied among streams.” HARVEY, B. C. and T. E. LISLE. 1999. Scour of Chinook Salmon Redds on Suction Dredge Tailings. North American Journal of Fisheries Management 19:613-617

  23. HARVEY, B. C. and T. E. LISLE. 1999. Scour of Chinook Salmon Redds on Suction Dredge Tailings. North American Journal of Fisheries Management 19:613-617 “The significance of dredge tailings to salmon populations may vary even among streams with similar patterns of scour. The proportion of Chinook salmon that spawn on dredge tailings would influence the population level effect of tailings anddepend, in part, on the availability of spawning sites on natural substrates. If natural spawning sites were relatively abundant and tailings were not strongly selected, a small fraction of redds would be located on tailings.”

  24. Once tailing piles are dispersed by high stream flows they do make up a component of the suitable spawning substrate. Approximately 60 salmonidredds were observed in a study on Canyon Creek, CA. None of the redds were found within dredge tailing piles. Stern, G. R. 1988. Effects of Suction Dredge Minin on AnadromousSalmonid Habitat in Canyon Creek, Trinity County, California. Masters Degree Thesis, Humbolt State University, 80p. “In the lower 6.8 mi of the Scott River in 1995, only 12 of 372 (3.2%)redds were located on tailings because much more natural substrate than dredge tailings provided spawning habitat and fish exhibited no strong preference for either substrate.” J. Kilgore, U.S. Forest Service, unpublished data During 1996-98 23.3 miles of the Trinity River was surveyed for fall Chinook salmon redds. Of the 1,717 redds found 23 (1.3%) were built on dredge tailings. Quihillalt, R.R. 1999. Mainstem Trinity River Fall Chinook Salmon Spawning Redd Survey, U.S. Fish & Wildlife Service, Arcata Fish & Wildlife Office, California

  25. Magneson, M., P. McNeil , and T. Shaw. 2001. Mainstem Klamath River fall Chinook salmon spawning survey 2001. U. S. Fish and Wildlife Service, Arcata Fish and Wildlife Office, Arcata Fisheries Data Series Report 2006-02, Arcata, California. • In 2001 there were 1,578 fall chinook redd counted in the Klamath River mainstem from the I-5 Bridge to Happy Camp. Two redd (0.127%), wereobserved on suction dredge tailings. • In 2002 there were 4,652 fall chinook redd counted in the Klamath River mainstem from the I-5 Bridge to Happy Camp. One redd (0.02%) was observed on suction dredge tailings. Magneson, M., P. McNeil , and T. Shaw. 2001. Mainstem Klamath River fall Chinook salmon spawning survey 2001. U. S. Fish and Wildlife Service, Arcata Fish and Wildlife Office, Arcata Fisheries Data Series Report 2006-02, Arcata, California. • In 2006 there were 1,186fall Chinook salmon redds counted in the mainstem Klamath River between Iron Gate Dam and the confluence of Indian Creek.No redds were observed on suction dredge tailings. Magneson, M., R. Studebaker, and J. Ogawa. 2008. Mainstem Klamath River Fall Chinook Salmon Spawning Survey 2006. U. S. Fish and Wildlife Service, Arcata Fish and Wildlife Office, Arcata Fisheries Data Series Report Number DS 2008-13, Arcata, California.

  26. Summary and Conclusions • Turbidity does not cause the water to warm and takes away nothing fish require. • Chemicals suspended in water fall out of suspension a short distance below the dredge. • Small-scale gold suction dredging temporarily effects a very small area in the environment relative to the entire area in which all dredges operate. • Excavations from dredging can result in temporarily formed pools (refugia) or deepen existing pools which may improve fish habitat. • Studies do not indicate any strong cumulative effects from multiple placer mining operations. • Few redds are constructed upon suction dredge tailings and usually only when natural substrates are in short supply.

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