1 / 46

Small-Scale Suction Gold Dredging

Small-Scale Suction Gold Dredging. Presented by: Joseph C. Greene, Research Biologist. Prepared for a Meeting with Oregon State Legislators, Oregon Small-scale Miners, and US EPA Region 10 Representatives. March 9, 2006 Oregon House Of Representatives Office Building, Salem, Oregon.

Download Presentation

Small-Scale Suction Gold Dredging

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Small-Scale Suction Gold Dredging Presented by: Joseph C. Greene, Research Biologist Prepared for a Meeting with Oregon State Legislators, Oregon Small-scale Miners, and US EPA Region 10 Representatives March 9, 2006 Oregon House Of Representatives Office Building, Salem, Oregon

  2. Small-Scale Suction Dredging and the Environment It is my opinion that the results from scientific investigations, presented in the Environmental Impact Reports, prepared by the State of California, Clearwater National Forest and Siskiyou National Forest, provide all the evidence required to support the determination that small-scale suction dredging is de minimis and impacts from these dredges are less than significant.

  3. Many people want outdoor settings to be left in a natural condition for quiet enjoyment. Thus suction dredging is perceived as a conflict with these activities. The noise of the suction dredge engines and exhaust fumes and the presence of the suction dredge activities may be the very things many people go outdoors to escape. However, suction dredgers also enjoy the outdoors. (CDFG, page V25) The “Real” Problem

  4. The “Real” Problem It should be noted that suction dredging is considered a legitimate activity on rivers and streams and suction dredge operators have a Federally mandated right to operate. Dredgers also have the basic right, of all citizens, to enjoy and utilize streams as long as their activities are in compliance with the laws and regulations of the State. ORS 541.110 provides, “the use of water of lakes and running streams of Oregon for the purpose of developing the mineral resources is declared to be a public and beneficial use and a public necessity.”

  5. For discussion the following excerpts were taken from the Draft Environmental Impact Report, Adoption of Amended Regulations for Suction Dredge Mining. 1997. State of California, Dept. of Fish and Game. The Conclusions in this report concur with those found in the Clearwater and Siskiyou National Forest Environmental Impact Reports. These documents are the culmination of literature searches for scientific evidence regarding the impacts of small-scale suction dredging on the environment and consultations with stakeholders and concerned citizens.

  6. 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 not indicate that suction dredge mining has no effect on the three responses measured, but rather any effect that may exist could not be detected at the commonly used Type I error rate of 0.05." (In other words, if there is an effect, it's so small they can't measure it.)

  7. 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."

  8. Dr. Bayley concluded… "Given that this analysis could not detect an effect averaged over good and bad miners and that a more powerful study would be very expensive, it would seem that public money would be better spent on encouraging compliance with current guidelines than on further study." Now, back to the comments published in the California Department of Fish and Game “Draft Environmental Impact Report”.

  9. The area or length of river or streambed worked by a single suction dredger as compared to total river lengthis relatively small compared to the total available area. An individual suction dredge operationaffects a relatively small portion of a stream or river. A small-scale suction dredge (representing 90-percent of all suction dredges) may spend a total of 4 to 8 hours per day in the water dredging an area from 1 to 10 m2 (3-33 ft2). Theaverage number of hours spent is 5.6 hours per day. The remaining time is spent working on equipment and processing dredged materials.

  10. Current regulations on most rivers and streams, in conjunction with riparian protective measures,results in a less than significant impact to channel morphology. Turbidity and sedimentation levelsgenerally return to background levels within 20 to 80 m (66-263 ft) below the dredging activities. In many of the studies performed on suction dredging, potentially adverse impacts to river resources were reported.Effects of increased turbidity levels and sedimentation, decreases in invertebrate populations and re-configuration of the streambed were temporary and localized.

  11. Suction dredgingcan have significant short-term and localized adverse impactson local benthic invertebrate abundance and community composition. However,over the long-term, the impacts appear to be less than significant. Colonies of invertebrates generally re-colonize areas disturbed by suction dredges within a relatively short period of time ranging from one to two months. Impacts to benthic invertebrate communities, from suction dredging,appear to be less than significant.

  12. Effects to benthic and/or invertebrate communities, turbidity and water quality appear to beless than significant. They are usually localized and temporary in duration!

  13. Impacts on Fish Effects from elevated levels of turbidity and suspended sediment normally associated with suction dredging as regulated in the past in Californiaappear to be less than significant with regard to impacts to fish and other river resourcesbecause of the level of turbidity created and the short distance downstream of a suction dredge where turbidity levels return to normal. Suction dredging appears to have little direct immediate physical effect on adult fishes in terms of harm from actual entrainment by dredges. ADULTS:

  14. Impacts on Fish Juveniles: Yolk Sac Fry: Entrained through a suction dredge does not appear to have a significant adverse effect on juvenile fish either. Entrainment can have a significant adverse effect on the more delicate stages of fish such as the yolk sac fry. During this stage the yolk sac can be easily ruptured or torn from the fish. Eggs: Developing eggs of salmonids are significantly adversely affected by entrainment through suction dredges. The degree of harm may vary depending on species.

  15. Impacts on Fish Current law requires that dredging operations must stop or move if redds are present during a permitted “In Water Work Period”. Fish eggs and yolk sac fry are protected by seasonal regulations that keep small-scale suction dredgers out of the rivers and streams during this season.

  16. Impacts on Spawning Gravel Most of the effects related to turbidity and sedimentation, and the disturbance of spawning gravels reported were temporary and localized, and therefore, represented impacts considered less than significant. Dredge piles do not appear to occupy a significant portion of the available spawning habitat so that dredge pile impacts are expected to be less than significant

  17. Impacts on Spawning Gravel Once tailing piles are dispersed by high stream flows they do make up a component of the suitable spawning substrate. Approximately 60 salmonid redds were observed in a study on Canyon Creek, CA. None of the redds were found within dredge tailing piles.

  18. Salmonids do not spawn in this type of coarse overburden

  19. Turbidity It has been asserted that salmon were not affected by elevated turbidity but studies have stated that salmonid growth was reduced at 25 NTU but not below. Turbidity caused by suction dredging is highly variable. Suction dredging bedrock pockets containing only sand and gravel causes virtually no change in turbidity whereas suction dredging clay deposits causes very noticeable turbidity.

  20. Flood Stage, Klamath River above Portuguese Creek, 2006

  21. 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.

  22. People with agendas often don’t put facts in perspective and blur the difference between facts and speculation

  23. Turbidity plumes, usually, do not cover wide areas of the stream and they are not continuous or consistent in sediment content

  24. Turbidity 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, particularly when one considers that turbidity levels return to normal levels on an average of 20-80 m (66-263 ft.) below the suction dredge. Also, natural levels of turbidity may be higher than levels of turbidity caused by suction dredging during certain times of the year.

  25. Notice the switch in plume turbidity density. Now the distant dredge plume is lower in suspend material concentration

  26. United States Department of Agriculture Forest Service Siskiyou National Forest, 200 NE Greenfield Road, Grants Pass, OR  97526-0242 Reply to: 2800 Date: October 16, 1995 Subject: A comparison of stream materials moved by mining suction dredge operations to the natural sediment yield rates To: The Record …”There are 1,092,302 acres on the Siskiyou National Forest. Using a factor of 0.33 cubic yards per acre per year times 1,092,302 acres will produce a very conservative estimate that 331,000 cubic yards of material move each year from natural causes compared to the 2413 cubic yards that was moved by suction dredge mining operations in 1995 on the Siskiyou. This would be a movement rate by suction dredge mining that equals about 0.7% of natural rates.” MICHAEL F. COOLEY, Recreation, Lands and Minerals Staff Officer, Siskiyou National Forest

  27. Constructing a nice deep hole for fish habitat while producing an almost imperceptible turbidity plume

  28. Fish Feeding Fish have been observed feeding in turbid plumes created by suction dredging. Stern (1988) observed young steelhead feeding on dislodged invertebrates in turbid dredge plumes, even though clear water was available nearby. Cutthroat and rainbow trout have also been observed feeding. The effects of suction dredging on the feeding of fish appears to beless than significant.Although invertebrate populations are negatively affected by suction dredging,the impacts are localized and short-term.

  29. Fish feeding below outfall from a small-scale suction gold dredge sluice box

  30. Behavior and Distribution Studies in Canyon Creek, Butte Creek, and the North Fork American River, CA did not indicate a difference in fish distribution or density below or above suction dredging sites. Stern (1988) reported that suction dredging did not appear to influence the behavior of adult spring-run salmonids in their summer holding areas.

  31. Behavior and Distribution Abandoned dredge holes can provide holding and resting areas for fish. Stern (1988) observed young steelhead in active and abandoned dredge holes in Canyon Creek. Suction dredge operators report adult salmon and steelhead moving into dredge holes overnight. Dredge holes often provide thermal and deeper water habitat for fish and some dredge holes in the Scott River, CA have held more juvenile salmonids than adjacent habitats.

  32. Benefits to the Environment Small-scale suction dredge miners remove lead shot, fishing sinkers, bullets and other metals and fragments from streams and rivers. Removal of these materials by suction dredgers is considered a benefit to the environment.

  33. Intention of Congress "The development of information which describes the relationship of pollutants to water quality is essential for carrying out the objective of the Clean Water Act.  This information, known as criteria, is required under Section 304(a) to be developed and published by the Administrator and issued to the states and public.Criteria to be developed in this section should draw upon the bestscientific knowledgeon the subject, including information, if any, from the National Academy of Sciences, the U.S Geological Survey in the Department of Interior, scholarly literature, academic experts, and other sources.”

  34. Establishing Effects of Pollutants “The concentration and dispersal of pollutants and their by products through biological, physical and chemical processes and any related changes in the diversity, productivity, or stability of receiving water ecosystems would be part of the information provided”. “Criteria establish the effects of pollutants on health or welfare, receiving water ecosystems and man, and identify the natural chemical, physical and biological integrity of the Nation's waters.”

  35. Natural Integrity of Waters …may be determined: Partially by consultation of historical records on species composition; Partially from ecological studies of the area or comparable habitats; and, Partially from modeling studies which make estimations of the balanced natural ecosystem based on available information.

  36. On Nov. 18, 1996, EPA and thetwo environmental groups entered into a settlement agreementto resolve the challenge to the general permit. The proposed permit sets conditions on the discharge - or release – of pollutants from the operation into waters of the United States. USEPA Fact SheetJanuary 14, 2000 The settlement agreement required EPA to complete two studiesrelated to the impact of placer mining on the natural environment in Alaska. One was to address the discharge of metals by placer mining operations and the other was to address the impact of suction dredge mining.

  37. Impact of Suction Dredging on Water Quality, Benthic Habitat, and Biota in the Fortymile River, Resurrection Creek, and Chatanika River, Alaska FINAL REPORT Submitted June 1999Prepared For:US Environmental Protection AgencyRegion 10Seattle, WashingtonPrepared By:Aaron M. Prussian, Todd V. Royer, and G. Wayne Minshall Department of Biological SciencesIdaho State UniversityPocatello, Idaho 

  38. Alaska Study Summary The report described the results of research into the effects of commercial and small-scale suction dredging on the water quality, habitat, and biota of Fortymile River, Resurrection Creek and the Chatanika River, Alaska. Focus of the work on Fortymile River was on an8-inch suction dredgelocated on the main stem and a10-inch suction dredgelocated on the South Fork.

  39. Alaska Study Summary Water chemistry measured on Fortymile River showed theprimary effects of suction dredging were increased turbidity, total filterable solids, and Cu and Zn concentrationsdownstream of the dredge. The results from this sampling revealed a relatively intense, but localized, decline in water clarity during the time the dredge was operating.These variables returned to upstream levels within 80-160 m (263-524 ft.) downstream of the dredge.

  40. Alaska Study Summary Macroinvertebrate abundance and diversity were greatly reduced in the first 10 m (33 ft.) below the dredge butreturned to values seen at the reference site by 80 to 160 m (263-524 ft.) downstream of the dredge. Cross-sectional profiles indicate that theimpact of the dredge piles relative to the width of theFortymileRiver was small. One year after dredging on the main stem and South Fork of Fortymile River,recovery of macro-invertebrate diversity appeared to be substantial.

  41. Alaska Study Summary Sampling was conducted on Resurrection Creek and on the Chatanika River, Alaska. The results from Resurrection Creek showed thatthere was no differencein the macro-invertebrate communitiesbetween the mining area and the locations downstream of the mining area,in terms of macroinvertebrate density, taxa richness, EPT richness, or food resources. The second component of this project is to examine the effects of small-scale suction dredging on smaller streams in Alaska.

  42. Alaska Study Summary • Results from the Chatanika River showedslight downstream decreases in macroinvertebrate density,but all other measures remained similar to those of the reference area. In general, the results arein agreement with other studies that have found only localized reductions in macroinvertebrate abundance in relation to small-scale suction dredging.

  43. USEPA Fact SheetJanuary 14, 2000The U.S. Environmental Protection Agency (EPA)Plans To Issue A Wastewater Discharge Permit To:Alaska Mechanical Placer MinersThis will also serve as a notice of a FINDING OF NO SIGNIFICANT IMPACT

  44. USEPA Fact SheetJanuary 14, 2000 The environmental groups believed that the suction dredge report (40-mile River, Resurrection Creek, and Chatanika River) did not address all of the required elements as set out in the 1996 settlement agreement. To avoid further litigationover the general permits,EPA and the environmental groups entered into another settlement agreement.

  45. The EPA had chosen to flex its legal muscle where scientific data does not justify their actions. Other Federal Agencies have stated the following: “. . . For decades, suction dredging has been essentially unmanaged. Its effects were considered insignificant and its consequences immeasurable.”(Siskiyou National Forest Draft Environmental Impact Statement). And, the U.S. Army Corps of Engineers stated,“To regulate against a potential for harm, where none has been shown to exist, is unjustifiable and must be challenged."

  46. Presented by Joseph C. Greene, Research Biologist (March 9, 2006 in Salem, Oregon)

More Related