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Upper Arkansas River
Mountain-Prairie Region
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Upper Arkansas River - Leadville, CO - California Gulch


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Arkansas River Near Leadville, CO. Credit: USFWS.

Arkansas River Near Leadville, CO. Credit: USFWS.

Background: The Leadville Mining District (California Gulch) has hundreds of abandoned mines, many miles of underground tunnels and shafts, large waste rock and tailings deposits and numerous processing facilities (some 75 mills and 44 smelters).  Waste products including mill tailings, slag, and dust were frequently placed in piles or tailings ponds; often in or adjacent to flood plain locations.  Over 2,000 waste rock piles cover approximately 627 acres.  Many of these exposed dumps remain as metal sources to the Arkansas River and other Basin tributaries.   In addition, blow outs of mine drainage tunnels combined with heavy spring runoff have transported an estimated 115,000 cubic yards of fluvial tailings to the flood plain of the Arkansas River.  These fluvial tails are being actively eroded by the river and result in ongoing metals releases.

The Arkansas River is used for recreation, irrigation of agricultural and range lands, and municipal drinking water.  Irrigation of rangeland and agricultural land with high metal content water may contribute to elevated levels of metals in animals and plants.  High metals concentrations along riverbanks can reduce or eliminate riverside vegetation, which increases erosion potential.  High metals concentrations in stream water can cause degradation of fish habitat, recreational areas, and agricultural land.  The Arkansas River seasonally exceeds state aquatic life standards for several metals including zinc, lead, cadmium, and copper.  

The Department of the Interior (DOI), State of Colorado (State), Environmental Protection Agency (EPA), U.S. Department of Justice (DOJ), and two of the primary potentially responsible parties (PRPs) have signed a Memorandum of Understanding (MOU) which sets up a two part process to restore the Upper Arkansas River Basin.  The first part of the process is to determine natural resource injury based on data and information currently available.  Upon Completion of injury determination, restoration alternatives will be developed.  The second part of the process will set up a facilitated negotiation intended to resolve the PRPs potential liability.

Public documents, links and contacts »

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Public Documents

Draft Restoration Monitoring and Outreach Plan for the Upper Arkansas River Watershed

Final Restoration Plan and Environmental Assessment for the
Upper Arkansas River Watershed

Executive Summmary 
Chapter 1
Chapter 2
Chapter 3
Chapter 4
Chapter 5
Chapter 6 and 7 
Appendix A
Appendix B
Appendix C

 Tiger and Dinero Tunnels Restoration

 Memorandum of Understanding (MOU)
(pdf, 252 kb) 

Scope of Work (SOW)
(pdf, 24 kb) 

Public Participation Plan
(pdf, 150 kb) 

Site Characterization Report (SCR)

Executive Summary/Table of Contents (pdf, 4.90 Mb)
Chapter 1 - Introduction  (pdf, 5.7 Mb)
Chapter 2 - Nature and Extent of Contamination (11-mile Reach)  (pdf, 24.9 Mb)
Chapter 3 - Description of Potential Resource Injuries and Related Pathways  (pdf, 1.4 Mb)
Chapter 4 - Target Restoration Areas  (pdf, 32.0 kb)
Chapter 5 - Recommendations for Early Actions  (pdf, 13.3 kb)
Chapter 6 - Upper Arkansas River Basin Downstream of the 11-mile Reach  (pdf, 5.56 Mb)
Chapter 7 - Smelter-Emissions Airshed  (pdf, 10.5 Mb)
Chapter 8 - References and Literature Cited  (pdf, 52.2 kb)
Appendix List / Appendix A - Bibliography  (pdf, 302 kb)
Appendix B - Hydrographs (pdf, 1.74 Mb)
Appendix C - Chemical Data, Biological Data, and Station Lists of Sampling Locations  (pdf, 281 kb)
Appendix D - Descriptions of Mine-Waste Deposits from Chapter 2  (pdf, 94.7 kb)
Appendix E - Water Quality Data (pdf, 218 kb)
Appendix F - Mass-Balance Calculations  (pdf, 166 kb)
Appendix G - Baseline Considerations (pdf, 155 kb)
Appendix H - Upper Arkansas River Mine-Waste Deposit Ranking (pdf, 74 kb)
Appendix I - Surface Water Figures  (pdf, 498 kb)
Appendix J - Terrestrial White Paper (pdf, 241 kb)

Restoration Alternatives Report (RAR) 
Full Restoration Alternatives Report with Appendices (pdf, 8.6 Mb) 
RAR Section 1 - Introduction (pdf, 3.2 Mb) 
RAR Section 2 - Summary of Relevant Findings (pdf, 1.9 Mb) 
RAR Section 3 - Restoration Needs (pdf, 3.0 Mb) 
RAR Section 4 - Indentification and Screening of Restoration Approaches (pdf, 1.9 Mb) 
RAR Section 5 - Development of Restoration Alternatives (pdf, 1.9 Mb) 
RAR Section 6 - Evaluation of Alternatives (pdf, 3.8 Mb) 
RAR Section 7 - Comparative Analysis, through Appendix A (pdf, 3.6 Mb) 

Preliminary Estimate of Damages

Chapter 1 (pdf 1.5 Mb)
Chapter 2 (pdf 3.14 Mb)
Chapter 3 (pdf 3.2 Mb)
Appendix (pdf 264 KB)

Links to more information 


     Mass Loading of Selected Major and Trace Elements in Lake Fort Creek near Leadville Colorado

U.S. EPA - 

  Colorado State Attorney Generals Office - 

  Colorado State Department of Health and Environment- 

  If you have any questions or comments related to the Upper Arkansas River Basin NRDA, contact us via email or telephone:

Laura ArchuletaContaminants Specialist, U.S. Fish and Wildlife Service, phone 719-655-6121, fax 719-655-2502.      



The mission of the U.S. Fish and Wildlife Service is working with Others to conserve, protect, and enhance fish, wildlife, plants and their habitats for the continuing benefit of the American People.
Last modified: June 30, 2014
All Images Credit to and Courtesy of the U.S. Fish and Wildlife Service Unless Specified Otherwise.
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