UNITED STATES ENVIRONMENTAL PROTECTION AGENCY REGION 8 1595 WYNKQOP DENVER, CO 80202-1129 Phone 800-227-8917

RECF WED JUL 2 0 2009

WTEA QVALI TY GUN?HOLU I I E I S I ~

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Mr. teve Gunderson Dire tor wat r Quality Control Division ~ololadoDepartment of Public Health and Environment 43 04 cherry Creek Drive South Denqer, Colorado 80246-1 53 0

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Re: TMDL Approvals Arkansas River - Segments COARUAOk COARUA02B, COARUAOZc,COARUA03, COARUA05, COARUAO7, COARUAII, COARUA12a .

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We h&e cmpleted our review of the total rnaxiqum daily loads (TMDLs) as submitted by your

offic, for the waterbodies listed in the enclasure to this lekter. In wordance with the Clean Water Act 125 1 et. seq.), we approve all aspects of TMDLs as developed for certain pollutants in water waterbodies as described in Section 303(d$(l). Based on our review, we feel the separate for the pollutants listed in the enclosed Ubles are adequately addressed, taking inta variation and a m g i n of safety.

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Thank you for submitting these TMDLs for our ravlew and approval. If you have any questions, the Most knowledgeable person on my staff is Sandra S p e b and she may be reached at (303) 3 12-6947.

C m l L. Campbell AssisffantRegional Administrator Offi& of Ecosystems Protection and Remediation

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Printed on Recycled Paper

***FINAL***

TOTAL MAXIMUM DAILY LOAD (TMDL) ASSESSMENT East Fork Arkansas River/Mainstem Arkansas River Lake County, Colorado June 2009 TMDL SUMMARY Main Mainstem of the East Fork of the Arkansas River Waterbody Name/Segment Number from a point immediately above the confluence with Birdseye Gulch to a point immediately above the confluence with California Gulch; COARUA02a Pollutant/Condition Addressed

Dissolved Zinc

Affected Portion of Segment

All

Use Classification

Aquatic Life Cold 1 Recreation E Water Supply Agriculture

Waterbody Designation

Reviewable

Water Quality Target

Zinc Acute = 0.978 e(0.8525[ln(hardness)]+1.0617) Zinc Chronic = 0.986 e(0.8525[ln(hardness)]+0.9109)

TMDL Goal

Attainment of acute and chronic table value based standard for dissolved zinc.

EXECUTIVE SUMMARY The Upper Arkansas River watershed spans both Lake County and Chaffee Counties, Colorado. This TMDL considers only Segment 2a which lies entirely in Lake County, Colorado. Segment 2a includes the mainstem of the East Fork of the Arkansas River from a point immediately above the confluence with Birdseye Gulch to a point immediately above the confluence with California Gulch. Segment 2a of the Upper Arkansas River Basin appears on the Colorado 2008 303(d) list for non-attainment of the Aquatic Life Use-based standard for dissolved zinc. The high concentration of this metal is primarily the result of historical mining activity in the area. There are no current active mining operations in this area. There is a permitted discharge on this segment for the Leadville Mine Drainage Tunnel Treatment Plant, permit # CO0021717. The treatment plant is owned and operated by the U.S. Bureau of Reclamation. I. INTRODUCTION Section 303(d) of the federal Clean Water Act requires states to periodically submit to the U.S. Environmental Protection Agency (EPA) a list of water bodies that are water-quality impaired. A water-quality impaired segment is a segment that does not meet the standards for its assigned use classification. The list of impaired water bodies is referred to as the “303(d) list”. [1]

***FINAL*** The list is adopted by the Water Quality Control Commission (WQCC) as Regulation No. 93 (WQCC, 2008). For water bodies and streams on the 303(d) list, a Total Maximum Daily Load (TMDL) is used to determine the maximum amount of a pollutant that a water body may receive and still maintain water quality standards. The TMDL is the sum of the Waste Load Allocation (WLA), which is the load from permitted and non-permitted point source discharge, Load Allocation (LA) which is the load attributed to natural background and/or non-point sources, and a Margin of Safety (MOS) (Equation 1). (Equation 1): TMDL=WLA+LA+MOS Alternatively, a segment or pollutant may be removed from the list if the applicable standard is attained, if implementation of clean-up activities via alternate means will result in attainment of standards, if the original listing decision is shown to be in error, or if the standards have been changed as the result of a Use Attainability Analysis (UAA), or other EPA approved recalculation method. The mainstem of the East Fork of the Arkansas River from a point immediately above the confluence with Birdseye Gulch to a point immediately above the confluence with California Gulch is included on the 2008 303(d) list for exceeding the Aquatic Life Use based chronic standard for dissolved zinc II. GEOGRAPHICAL EXTENT The Arkansas River originates in Lake County, Colorado just north of the town of Leadville. The Upper Arkansas lies just east of the Sawatch mountain range and is flanked to the west by Mt. Elbert, the highest peak in Colorado at 14,443 feet. Many tributaries flow into the Upper Arkansas River and several of its designated segments are listed on the 303(d) list due to historical mining influence in the area. The Arkansas River flows in a southeastern direction out of Colorado. Along the way, it forms Lake Pueblo and John Martin Reservoir before eventually leaving the state just east of Lamar. Segment 2a of the Upper Arkansas is approximately 11 miles in length. The segment begins at the confluence of the East Fork Arkansas River with Birdseye Gulch and continues to the confluence of the mainstem Arkansas with California Gulch (Figure 1). Within the segment is the Leadville Mine Drainage Tunnel Treatment Plant which discharges into the East Fork section of the segment. The treatment plant is operated by the Bureau of Reclamation, and began treatment in 1992. The plant was constructed to treat metals discharge from the Leadville Mine Drainage Tunnel.

[2]

***FINAL***

Figure 1. Upper Arkansas River Segment 2a and vicinity. Much of the heavy metals loading throughout the Upper Arkansas basin is the result of natural geologic conditions and historic mining activities. Within this basin lies the historic “mineral belt” area near the town of Leadville. The geology and mineralization of the area is fairly complex and generally of three types: massive sulfide replacement deposits, veins, and high-temperature deposits characterized by magnetite, garnet, and molybdenite occurring as veins, disseminations, and replacement bodies. Sulfide mineralization containing various concentrations of lead, zinc, gold, silver, copper and molybdenum is predominant throughout the district. The upper Arkansas River has long been impacted by metals contamination from [3]

***FINAL*** historical mining activities. Construction of the Leadville Mine Drainage Tunnel was initiated in 1943 by the Bureau of Mines to provide drainage of seepage from some of the underground mine workings in the area so that development of mineral reserves could continue. The Bureau of Reclamation acquired the LMDT in March of 1952 to use the water for water rights to supply the Fryingpan-Arkansas Project. These waters were contaminated with heavy metals loading and discharged into the East Fork. To bring the discharge into compliance with the Clean Water Act, a chemical precipitation water treatment plant was constructed and began operation in 1992. Since its completion in 1992, The LMDT Treatment Plant has helped to reduce metals loading into the East Fork significantly. Further downstream in the Upper Arkansas basin, much remediation work has been completed at the California Gulch Superfund site, which continues to this date. The Upper Arkansas River basin has experienced a dramatic reduction in toxic metals contamination as a direct result of the above mentioned projects. This improvement in water quality has been beneficial to both the local community and environment. However, there are still many water quality issues associated with natural geologic conditions and historical mining activities. II. WATER QUALITY STANDARDS Standards Framework Waterbodies in Colorado are divided into discrete units or “segments”. The Colorado Basic Standards and Methodologies for Surface Water, Regulation 31 (WQCC 2006a), discusses segmentation of waterbodies in terms of several broad considerations: 31.6(4)(b)…Segments may constitute a specified stretch of a river mainstem, a specific tributary, a specific lake or reservoir, or a generally defined grouping of waters within the basin (e.g. a specific mainstem segment and all tributaries flowing into that mainstem segment.) (c) Segments shall generally be delineated according to the points at which the use, physical characteristics or water quality characteristics of a watersource are determined to change significantly enough to require a change in use classifications and/or water quality standards. As noted in paragraph 31.6(4)(c), the use or uses of surface waters are an important consideration with respect to segmentation. In Colorado, there are four categories of beneficial use which are recognized. These include Aquatic Life Use, Recreational Use, Agricultural Use, and Water Supply Use. A segment may be designated for any or all of the “Use Classifications”. 31.6 Waters shall be classified for the present beneficial uses of the water or the beneficial uses that may be reasonably expected in the future for which the water is suitable in its’ present condition or the beneficial uses for which it is to become suitable as a goal. Each assigned use is associated with a series of specific numeric standards. These pollutants may vary and are relevant to a given Classified Use. Numeric standards are identified in sections 21.11 and 31.16 of the Basic Standards and Methodologies for Surface Water. [4]

***FINAL*** Uses and Standards addressed in this TMDL Date (Cycle Year) of Current Approved 303(d) list: 2008 WBID Segment Description Designated Uses & Impairment Status Mainstem of the East Fork of the Arkansas River from a point Aquatic Life Cold 1: Impaired immediately above the confluence Recreation E: Not Impaired COARUA02a with Birdseye Gulch to a point Water Supply: Not Impaired immediately above the confluence Agriculture: Not Impaired with California Gulch Table 1. Designated uses and impairment status for Upper Arkansas Segment 2a. The Colorado Basic Standards and Methodologies for Surface Water, Regulation 31 identifies standards applicable to all surface water statewide (WQCC, 2006a). The pollutant of concern for this assessment is dissolved zinc. The specific numeric standard assigned to the Upper Arkansas Segment 2a is contained in the Classifications and Numeric Standards for the Arkansas River Basin, Regulation 32 (WQCC, 2006b). In this instance, dissolved zinc concentrations exceed the Aquatic Life Use-based standard intended to protect against shortterm, acutely toxic conditions (acute) and longer-term, sub-lethal (chronic) effects. Water Quality Criteria for Impaired Designated Uses WBID

Impaired Designated Use

COARUA02a

Aquatic Life Cold 1

Applicable Water Quality Criteria and Status Dissolved Zinc (1) / Not Attained

Applicable State or Federal Regulations: (1) Classifications and Numeric Standards for the Arkansas River Basin, Regulation No. 32 Table 2. Ambient water quality criteria and status for 303(d) listed Upper Arkansas Segment 2a. Chronic and acute standards are designed to protect against different ecological effects of pollutants (long term exposure to relatively lower pollutant concentrations vs. short term exposure to relatively higher pollutant concentrations). Where chronic standards are assigned, they were used because they represent a more conservative approach than the acute standards. Chronic standards represent the level of pollutants that protect 95 percent of the genera from chronic toxic effects of metals. By reducing metals concentrations to attain the chronic standard, the acute standard will also be attained. Per Regulation 31, chronic toxic effects include but are not limited to demonstrable abnormalities and adverse effects on survival, growth, or reproduction (WQCC 2006b). IV. PROBLEM IDENTIFICATION To a great extent, heavy metal loading throughout the Arkansas has been the combination of both natural geologic conditions and historic mining activities as opposed to permitted source discharges. From the earliest gold discoveries in the 1860’s, intermittent periods of active mining and lulls occurred within the district. The district produced silver, molybdenum, lead, [5]

***FINAL*** zinc, copper, and gold ores. Prior to 1900, silver and lead were the primary commodities; while after 1900, zinc and molybdenum ores produced the highest values. The fine waste material remaining after the processing of metals is referred to as mine “tailings”. These tailings were deposited adjacent to or directly down-gradient of the mill. In that period prior to modern environmental laws or regulations, gravity was the principal disposal method for mining wastes. Due to the sizeable quantities of mine waste rock and the slow biogeochemical process of acid rock discharge, this pollutant continues to flow long after the mining ends. As mentioned earlier in this document, segment 2a of the Upper Arkansas River Basin appears on the Colorado 2008 303(d) list for non-attainment of dissolved zinc. The high concentration of this metal is primarily the result of historical mining activity in the area. The levels of dissolved zinc exceed the acute and chronic TVS primarily in the months of May and June. This coincides with spring snowmelt and runoff period. Other exceedances of the acute TVS standard occurred in 1999, prior to remediation of the Stork Yard site located in the upstream segment. Arkansas Segment 2a has been in attainment of its acute standard since 2003. The data used in this TMDL was collected at sites labeled AR-1 and AR-2 (Figure 1). Site AR-2 is located on the Arkansas River, approximately 100 feet above the confluence with California Gulch. Site AR-1 is located further upstream on the Arkansas River. Water quality Data was collected as part of a collaborative effort with DOW, EPA, CDPHE, Resurrection (Newmont) Mining Company and ASARCO. Data sets for the sample sites go back to late 1995 and continue through late 2007. The total number of samples collected at site AR-2 is 154, while 644 samples have been collected at site AR-1.

Figure 1. Monthly dissolved zinc concentrations in Segment 2a at site AR-1. Boxes represent the upper and lower quartile values while whiskers represent 5th and 95th percentile values. The red dashes indicate median zinc concentrations. (Period of record: Oct. 1995 thru Oct. 2006) [6]

***FINAL***

Figure 2. Monthly dissolved zinc concentrations in Segment 2a at site AR-2. Boxes represent the upper and lower quartile values while whiskers represent 5th and 95th percentile values. The red dashes indicate median zinc concentrations. (Period of record: Oct. 1995 thru Oct. 2007) V. WATER QUALITY GOALS Segment 2a is classified for the Aquatic Life Cold 1, Recreation E, Water Supply and Agriculture uses. The Aquatic Life Use-based table value standards are calculated by using the hardness-based equations specified in Regulation 32. The goal of this TMDL is attainment of the table value based standard applied as the 85% ambient concentration. Attainment of the table value based standard is protective of all assigned beneficial uses, including Aquatic Life Use. VI. INSTREAM CONDITIONS Hydrology The hydrograph of the Upper Arkansas River is typical of other high mountain streams. Low flows occur in the late fall to early spring, followed by large increases in flow during the annual snowmelt period. The snowmelt period starts in late spring, usually May, and tails off through the summer. The smaller tributaries show the same pattern, but tend to show greater influences from summer rain events. The flow data used in this TMDL was from October 1967 through September 2006.

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***FINAL***

Figure 3. Box and whisker plots for median monthly flow on the East Fork of the Arkansas River at Highway 24. Boxes represent upper and lower quartile values while whiskers represent 5th and 95th percentile values. Red dashes indicate median flows. (Period of Record: Oct. 1967 thru Sep. 2006) Climate Climate data for the area is collected at the Twin Lakes weather station. The weather station is located near Upper Arkansas segment 2a and will be used for this TMDL. Climate data for this station was collected from August 1949 through December 2007. Temperatures in the area were typical for high mountain elevations with variations in temps during seasonal weather patterns. A summary of the climate data is provided below: Average annual precipitation (in.): 9.63 Month of highest precipitation: August (1.55 in.) Month of lowest precipitation: January/February (0.47 in.) Average annual snowfall (in.): 45.7 Average annual temperature: 36.7°F Month of lowest average temperature: February (3.8°F) Month of highest average temperature: July (73.3°F) (source: www.wrcc.dri.edu )

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***FINAL*** Ambient Water Quality TVS Chronic Ambient Number of Mean Hardness Dissolved Zinc Dissolved Zinc Month samples mg/L Standard ug/L ug/L January 3 114.9 139.9 42.9 February 4 124.7 150 22.1 March 8 119.6 144.8 25.8 April 11 92.7 116.5 69.5 May 38 50.2 69.1 106.8 June 16 43.5 61 81.3 July 12 68.1 89.6 26.7 August 13 92.2 116 65.2 September 13 97.7 121.9 28.4 October 19 107.5 132.2 25.7 November 14 113.4 138.4 44.9 December 3 118.4 143.6 35.4 Table 3. Average hardness and chronic stream standards for 303(d) listed segment COARUA02a from late 1995 through late 2007 (n=154). To determine chronic exceedances of the table value-based stand for zinc, monthly ambient zinc concentrations were calculated using the data set for site AR-2. Monthly mean hardness values were also calculated using the data set for site AR-2. The monthly mean hardness values were then applied to the table value based formula to determine the chronic dissolved zinc standards and then compared to the ambient dissolved zinc concentrations to establish the monthly exceedances. The exceedances of the table value-based standard for dissolved zinc occur in the months of May and June. These exceedances coincide with snowmelt and the subsequent spring runoff. The table value acute dissolved zinc standard was calculated with the data set for site AR2. There were 25 exceedances out of 140 samples for an 18% exceedance rate. The bulk of the exceedances occurred in the months of May and June prior to the year 2000, which coincided with seasonal snowmelt. There were 3 exceedances that occurred outside of the months of May or June. These exceedances occurred once for the months of April, October, and November and all were in the year 1999. Since attainment of the acute standards is based on the most recent five year period of record, and there have been no exceedances since 2003, Segment 2a would be in attainment of its acute dissolved zinc standard. The acute TVS exceedances are contained within this TMDL’s load allocations and required load reductions. AR-2 data is used in the calculations for this TMDL as site AR-2 is the furthest site downstream within segment 2a. A similar table which addresses exceedances of acute table value standards is included in Appendix A. Only samples with paired hardness values were used [9]

***FINAL*** to illustrate acute exceedances (n=140), consequently, fourteen additional samples were used to calculate ambient monthly concentrations. Using site AR-2 in this TMDL will reflect attainment of the acute and chronic TVS zinc standards throughout the entire segment. VII. SOURCE ANALYSIS Metals loading in the Upper Arkansas River basin is mainly due to historic mining activities and natural geologic conditions. As mentioned earlier in this TMDL, exceedances of the chronic table value based zinc standard (using 85 % zinc concentrations) for Aquatic Life occur only in the months of May and June using the last five years of data. This coincides with high flows due to snowpack runoff and low hardness values. The Leadville Mine Drainage Tunnel has a National Pollutant Discharge Elimination System (NPDES) permit issued by the U.S. Environmental Protection Agency (EPA). This NPDES permit contains effluent limits for zinc that are based on the assigned water quality standard. In fact, discharging concentrations are typically reported as less than the detection limit (10ug/L). The LMDT Treatment Plant has maintained compliance with the effluent limits set in the NPDES permit. The Water Quality Control Division (WQCD) has determined the treated discharge is not a significant contribution to the segment’s non attainment of the zinc standard. Zinc loading does not appear to be coming from the upstream Segment 1b which was assigned chronic table value and site specific acute standards for zinc in June of 2007. Within segment 1b is the inactive Climax molybdenum mine, the largest in the world at one point in time. In 2003, the Climax Mine and WQCD began working cooperatively on a TMDL for segment 1b that was later approved by the Environmental Protection Agency. Climax took voluntary action in 2005 to remove and reclaim tailings identified in the Segment 1b TMDL as contributing to the lead and zinc loading to the East Fork Arkansas River. Subsequent to remediation, the Water Quality Control Commission found that the acute TVS for zinc was unattainable due to natural and anthropogenic factors and thus adopted a sitespecific acute standard for zinc for Segment 1b in 2007. The site-specific standard was based on the 95th percentile of the previous three years of data for the segment. Currently however, Segment 1b is in attainment of acute and chronic table value standards for dissolved zinc as a result of the remediation work performed by the Climax Mine. The Commission will review the site-specific standard in 2012 and determine whether it is still appropriate. In February of 2008, Lake County declared a state of emergency over blockages in the Leadville Mine Drainage Tunnel (LMDT) in Segment 2a. The blockages were causing water, estimated to be around a billion gallons or more, to backup in the tunnel. The concern stemmed from the potential for a sudden release that could send a large amount of metals-laden water through the tunnel into the Arkansas River and possibly cause flooding in the area near the tunnel. In addition, rising groundwater levels and a heavy snow pack were increasing the concern. [10]

***FINAL*** Local and state officials requested that the Federal government address the issue immediately. The Bureau of Reclamation contended the water came from the EPA Superfund site and thus, they did not have the authority to do anything about it. Bills were introduced in both the U.S. House and Senate to force the federal agencies to address the issue. The EPA agreed to start pumping water out of the Gaw shaft and construct a relief well in the LMDT to pump water out of the tunnel. Initially water was pumped from the Gaw shaft directly into the Arkansas River once it was determined to be clean enough. Later, in June 2008, the EPA pumped water from the Gaw shaft and the LMDT relief well directly to the Bureau of Reclamation treatment plant for treatment before discharging into the river. VIII. TMDL ALLOCATION Allocation Methodology As noted above, increased levels of zinc over the TVS are a result of natural geologic conditions and historic mining activities in the area. In order to attain the TVS for zinc, load allocations have been assigned to reach the goal of this TMDL. The loading reductions have been assigned to non-permitted discharges related to historic mining activities. Total Maximum Daily Loads A TMDL is comprised of the sum of the Waste Load Allocation (WLA), Load Allocation (LA), and a Margin of Safety (MOS). The Waste Load Allocation consists of the permitted and nonpermitted point sources within the segment. The Load Allocation is the pollutant load attributed to natural background, also referred to as non-point sources. TMDL = Sum of Waste Load Allocations + Sum of Load Allocations + Margin of Safety Waste Load Allocation As stated earlier in this TMDL, there is only one permitted discharger on segment 2a. The LMDT Treatment Plant operates under an EPA issued permit. The LMDT permit discharge limits are based upon the segment’s applicable water quality standards. The LMDT Treatment Plant is meeting its permitted discharge limits and is not considered to be a significant contributor to the segment’s exceedance of the TVS for dissolved zinc. The LMDT is assigned a discreet WLA in this TMDL. It should be noted that the LMDT waste load allocation is not subject to the instream load reductions. The WLA for the Leadville Mine Drainage Tunnel was calculated based on the design capacity for flow * effluent limit * conversion factor (0.0054) to obtain a load in lbs/day. The effluent limitations for the LMDT Treatment Plant are divided into high flow and low flow seasons. High flow effluent limitations are effective during the months of May thru August. The water quality based effluent limit (WQBEL) was determined to be 84 ug/L dissolved zinc during high flow. The low flow effluent limitations are effective during September thru April. The WQBEL was determined to be 129 ug/L dissolved zinc during low flow. Due to the lack of downstream capacity from the seasonal loading analysis, the seasonal “end-of-pipe” limits have been applied to ensure water quality protection. [11]

***FINAL*** Zinc loading in the mainstem Arkansas segment 2a is impacted by abandoned mine features in tributary watersheds (e.g. Evans Gulch, St. Kevin’s Gulch). This impact is primarily observed during the months of peak runoff, May and June. Therefore, the remaining WLA is considered to be from non-permitted point source discharges from historic mining activities. Load Allocation Natural background zinc concentrations are considered in the LA portion of this TMDL. Natural background zinc concentrations were determined by using data from the end of segment 1b which is directly upstream of segment 2a and ends at Birdseye Gulch. Data was used from a sample site just below the Climax Mine area. Only data after Climax Mine’s voluntary remediation in 2005 was used for determining background concentrations. The determined dissolved zinc background was then subtracted from the ambient concentration (85th percentile) of zinc for segment 2a. Since zinc concentrations in Segment 1b were less than the detection limit, concentrations were set to the detection limit of 30 ug/L. Margin of Safety In accordance with the Federal Clean Water Act, a margin of safety was included in this TMDL. The margin of safety is required to be included to account for the uncertainty about the relationship between the pollutant and the receiving waterbody. The MOS can be implicit or explicit. An implicit MOS was used in this TMDL development. The TMDL was calculated using a monthly median flow multiplied by the existing stream standard and a conversion factor (0.0054) to approximate a load in pounds/day. Ambient stream loads were approximated by multiplying 95th percentile metals concentrations by median flows (monthly or annual, where applicable). This also ensures that reductions necessary to attain chronic standards will also ensure attainment of acute standards. By incorporating the critical condition into the calculation of the TMDL, load reductions tend to be overestimated. The incorporation of monthly TMDLs reflects the seasonality of metals load reductions in the upper Arkansas River basin and more adequately reflects the current water quality situation. As stated above, data used for calculations of background were below detection limits. Therefore, the given detection limit of 30 ug/L was assigned as background. The use of the detection limit as background adds a conservative element to the ambient stream concentration calculation

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***FINAL***

Month

Ambient Stream Conc. (lbs/day)

TMDL=TVS * Median Flow * 0.0054

WLA LMDT (lbs/day)

WLA (lbs/day)

LA (lbs/day)

% Reduction needed to attain chronic tvs

January

3.91

11.33

4.27

4.52

2.54

0%

February

1.80

11.34

4.27

4.53

2.55

0%

March

2.53

11.73

4.27

4.77

2.68

0%

April

26.33

15.73

4.27

7.33

4.13

40%

May

146.78

46.26

2.78

27.82

15.65

68%

June

140.21

93.27

2.78

57.91

32.57

33%

July

49.32

52.73

2.78

31.97

17.98

0%

August

29.21

30.69

2.78

17.86

10.05

0%

September

5.89

21.06

4.27

10.74

6.04

0%

October

8.99

18.56

4.27

9.15

5.14

0%

November

23.08

15.69

4.27

7.31

4.11

32%

December

3.39

13.18

4.27

5.70

3.21

0%

Table 4. TMDL allocations for Segment 2a of the Upper Arkansas River. Loads were calculated in pounds per day. Based on differences in upstream and downstream dissolved zinc concentrations, 64% of the zinc load remaining after the permitted WLA was calculated, was attributed to the influence of abandoned mine sources. Subsequently, the remaining load was attributed to the LA (natural background or non-point sources). Based on the TMDL calculations, the following load reductions are needed for Segment 2a to meet the chronic TVS for dissolved zinc: a 40% load reduction in April, a 68% load reduction in May, a 33% load reduction in June, and a 32 % load reduction in November. All of the loads in this TMDL are based on median monthly flows and 95th percentile concentrations of dissolved zinc from site AR-2 data. Chronic load reductions were applied to sample data to assess attainment of acute dissolved zinc standards. If chronic load reductions are achieved, it is anticipated that Segment 2a will be in attainment of its acute zinc table value standard. IX. RESTORATION PLANNING AND IMPLEMENTATION PROCESS Water Quality Improvements in the Watershed Previous improvements to the watershed include the building of the Leadville Mine Drainage treatment plant in Segment 2a. In Segment 1b, there has been prior cleanup work performed by the Climax Mine. This remediation work includes removal of settling basins and waste piles, reclamation of aggregate pits, and reconstruction of stream channels. There are no additional planned remediation projects currently in Segments 1a, 1b, or 2a. [13]

***FINAL*** Monitoring In order to ensure that this TMDL is adequately protective of the segment, additional monitoring is necessary. Monitoring of sites AR-1 and AR-2 is ongoing and will continue into the future. Goal The goal of this TMDL is to ensure that Segment 2a is in attainment of the chronic and acute TVS for dissolved zinc. Attainment of the acute and chronic TVS for dissolved zinc will help protect the beneficial uses of Segment 2a, including the Aquatic Life use. X. Public Involvement The public has had the opportunity to be involved in the Water Quality Control Commission (WQCC) hearings since 1996 when the WQCC adopted ambient-based standards. Opportunities have also been available through the 303(d) listing process which also has a public notice period for public involvement. A draft of this TMDL was on public notice in the Water Quality Bulletin in May 2009 so that the public would have an opportunity to comment on this TMDL. There were no public comments received for this document. XI. References WQCC 2008: Colorado Department of Public Health and Environment, Water Quality Control Commission, Section 303(d) List Water-Quality-Limited Segments Requiring TMDLS, Regulation #93, Adopted March 11, 2008. WQCC 2008: Colorado Department of Public Health and Environment, Water Quality Control Commission, Classification And Numeric Standards For Arkansas River Basin, Regulation No. 32, Amended July 15, 2008. WQCC 2008: Colorado Department of Public Health and Environment, Water Quality Control Commission, The Basic Standards And Methodologies For Surface Water, Regulation NO. 31, Amended January 14, 2008. U.S. Department of the Interior, Bureau of Reclamation: A Summary of Existing Reports which have Examined the Leadville Mine Drainage Tunnel (LMDT) Discharge to the East Fork of the Arkansas River, Colorado, Technical Memorandum 8220-05-11, April 2005.

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***FINAL*** Appendix A. date 06-Oct-95 25-Oct-95 09-Jan-96 26-Mar-96 08-May-96 09-May-96 15-May-96 17-May-96 05-Jun-96 11-Jun-96 10-Jul-96 14-Aug-96 11-Sep-96 24-Sep-96 03-Oct-96 13-Nov-96 29-Apr-97 07-May-97 14-May-97 03-Jun-97 10-Jun-97 26-Jun-97 13-Aug-97 27-Aug-97 30-Sep-97 01-Oct-97 06-May-98 11-May-98 28-May-98 15-Jul-98 22-Sep-98 08-Oct-98 09-Oct-98 20-Nov-98 18-Dec-98 08-Jan-99 10-Feb-99 19-Mar-99 09-Apr-99 03-May-99 07-May-99 11-May-99 24-May-99 11-Jun-99 14-Jun-99 30-Jun-99

hardness mg/L 82 94 106 117 44 49 42 39 39 38 56 88 96 97 88 114 84 56 56 37 40 45 64 75 88 104 60 54 43 61 107 102 92 130 121 121 121 138 111 70 58 88 39 27 44 27

zinc tvs (ac) 121 136 151 164 71 78 68 64 64 63 87 129 138 140 129 160 124 87 87 61 66 73 98 112 129 148 93 85 70 94 152 146 134 179 168 169 169 189 157 106 90 129 64 47 71 46

sample zinc ug/L 37 28 51 34 78 71 115 95 61 54 28 24 23 26 17 31 56 61 110 81 81 34 51 33 25 23 65 57 50 24 23 19 307 394 30 18 18 26 307 46 1727 45 73 100 48 39

Table 5. Average hardness and acute stream standards for 303(d) listed segment COARUA02a from late 1995 through late 2007 (n=140). [15]

***FINAL*** Appendix A. (continued) date 16-Jul-99 01-Sep-99 15-Sep-99 01-Oct-99 13-Oct-99 21-Oct-99 19-Nov-99 17-Dec-99 28-Jan-00 25-Feb-00 31-Mar-00 20-Apr-00 02-May-00 19-May-00 22-May-00 26-Jun-00 30-Jun-00 28-Jul-00 29-Aug-00 30-Aug-00 21-Sep-00 30-Oct-00 31-Oct-00 01-Nov-00 02-Nov-00 03-Nov-00 04-Nov-00 05-Nov-00 06-Nov-00 07-Nov-00 08-Nov-00 09-Nov-00 01-May-01 15-May-01 16-May-01 17-May-01 18-May-01 19-May-01 20-May-01 23-May-01 30-May-01 10-Jul-01 11-Jul-01 06-Aug-01 01-Oct-01 10-Apr-02

hardness mg/L 37 51 95 69 100 99 120 118 117 114 112 73 64 53 48 59 59 81 101 84 105 102 237 103 104 103 106 105 116 125 115 115 52 37 33 33 37 36 35 49 39 62 64 76 115 76

zinc tvs (ac) 62 81 137 104 143 143 167 166 164 160 158 110 98 84 77 91 91 120 145 123 149 146 299 147 149 147 150 149 163 174 161 162 82 62 55 56 61 60 59 78 64 95 98 113 162 113

sample zinc ug/L 26 36 14 18 16 24 23 22 24 19 20 83 62 89 67 29 15 15 64 17 16 15 17 19 21 17 101 15 42 20 21 28 60 0 67 89 105 97 86 92 74 20 24 31 19 10

Table 5. Average hardness and acute stream standards for 303(d) listed segment COARUA02a from late 1995 through late 2007 (n=140). [16]

***FINAL*** Appendix A. (continued) date 22-Apr-02 23-Apr-02 01-May-02 16-Aug-02 09-Oct-02 24-Oct-02 14-Nov-02 11-Feb-03 26-Mar-03 09-Apr-03 16-Apr-03 01-May-03 16-May-03 22-May-03 23-May-03 28-May-03 20-Jun-03 22-Jul-03 22-Jul-03 19-Aug-03 24-Sep-03 20-Oct-03 17-Mar-04 19-Mar-04 01-Apr-04 07-May-04 22-Jun-04 14-Jul-04 24-Aug-04 14-Sep-04 19-Oct-04 24-Feb-05 21-Mar-05 18-Apr-05 17-May-05 23-Jun-05 20-Jul-05 16-Aug-05 15-Sep-05 18-Oct-05 14-Mar-06 17-Apr-06 17-May-06 13-Jun-06 17-Jul-06 14-Aug-06

hardness mg/L 85 85 70 146 110 118 120 136 125 117 102 71 63 45 40 35 49 81 76 89 106 112 126 98 86 50 50 75 91 117 107 128 125 97 57 40 73 94 109 104 116 95 48 49 82 106

zinc tvs (ac) 125 125 106 198 155 165 167 186 173 164 146 107 97 73 66 58 78 120 114 129 151 158 175 141 126 80 79 112 133 164 152 177 173 140 89 66 110 136 155 149 162 137 77 78 121 151

sample zinc ug/L 17 0 26 10 10 15 22 16 19 16 23 109 155 86 85 57 42 18 14 20 27 18 14 18 37 70 36 24 24 19 25 25 19 27 67 24 22 23 33 15 21 45 101 35 19 13

Table 5. Average hardness and acute stream standards for 303(d) listed segment COARUA02a from late 1995 through late 2007 (n=140). [17]

***FINAL*** Appendix A. (continued) date 13-Sep-06 04-Oct-06

hardness mg/L 104 97

zinc tvs (ac) 148 140

sample zinc ug/L 14 20

Table 5. Average hardness and acute stream standards for 303(d) listed segment COARUA02a from late 1995 through late 2007 (n=140).

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