UNITED STATES ENVIRONMENTALPROTECTION A REGION 8 1

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1595 Wynkoop stk t DENVER, tCf 8020i-1129 Phoqa 800-227-8417

Ref: 8EPR-EP

Mr. Steve Gundenon Director Water Quality Control Division Colorado Department of Public Health and Environment 4300 Cherry Creek Drive South Denver, Colorado 80246-1530 for copper (Cu)

We have completed our review of the tototal maximum Lilyloads (TMDLs) as submined by your ofice on Nov 5,20 10 for the waterbody listed in the enelow4 to this l e e . In accordance with the Clean W a t a Act (33 U.S.C. 1251 et. seq.), we approve all aspects of TMDLs as developed for certain pollutants,in water quality limited waterbodies as described in Fection 303(6)(1). Based on our review, we feel the separate TMDL elements for the pollutant listed in the enclosed table are adequately addressed, taking into wnsidemtion seasonal variation and a *n of safety. Thank you for submitting these TMDLs for ow review and approval. If you have any questions, the most knowledgeable person on my staff is Julie Kinsey and she may be reached at (303) 3 12-7065. Sincerely,

I

Cam1 L. cdnpbelt

Assistant Regional Administrator Office of Ecpsystems Protection and Retnediatiun

Enclosures

@

Printed an Recycled Paper

**FINAL** TOTAL MAXIMUM DAILY LOAD (TMDL) ASSESSMENT Lake Creek Lake County, Colorado November 2010 TMDL SUMMARY Waterbody Name/Segment Number Main Mainstem of Lake Creek and all tributaries, wetlands, lakes and reservoirs from source to confluence with the Arkansas River (including Twin Lakes Reservoir); COARUA10 Pollutant/Condition Addressed

Dissolved Copper

Affected Portion of Segment

Mainstem of Lake Creek and all tributaries and wetlands

Use Classification

Aquatic Life Cold 1 Recreation E Water Supply Agriculture

Waterbody Designation

Reviewable

Water Quality Target

Chronic dissolved copper standard of less than or equal to 8ug/L (site-specific standard). Acute dissolved copper standard (table value standard).

TMDL Goal

Attainment of assigned acute and chronic standards for dissolved copper.

EXECUTIVE SUMMARY The Upper Arkansas River watershed spans both Lake County and Chaffee Counties, Colorado. This TMDL focuses on Segment 10 which lies entirely in Lake County, Colorado. Segment 10 includes the mainstem of Lake Creek, Twin Lakes Reservoir, and all tributaries that flow into Lake Creek. The segment ends at a point immediately above the confluence with the Upper Arkansas River. Segment 10 of the Upper Arkansas River Basin appears on the Colorado 2010 303(d) list for non-attainment of the Aquatic Life Used-based standard for dissolved copper, pH, and Dissolved Oxygen (DO). The high concentration of copper is primarily the result of natural geologic conditions in the area. [1]

**FINAL** 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”. The list is adopted by the Water Quality Control Commission (WQCC) as Regulation No. 93 (WQCC, 2010). 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. Segment 10 of the Upper Arkansas River is included on the 2010 303(d) list for exceeding the Aquatic Life Use based chronic standard for dissolved copper, pH, and dissolved oxygen. The segment includes all of Lake Creek to its’ confluence with the Arkansas River, including all tributaries that flow into Lake Creek and Twin Lakes Reservoir. 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 ft. 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 10 of the Upper Arkansas is around 20 miles in length originating at Peekaboo Gulch to its’ confluence with the Upper Arkansas River. It is located just east of the Continental [2]

**FINAL** Divide in the Sawatch Mountain Range. Much of the area and lands surrounding the watershed are part of the San Isabel National Forest. The Lake Creek watershed (Figure 1.) begins in various gulches and drainages that flow into a North Fork Lake Creek and a South Fork Lake Creek. The two forks merge to form the mainstem of Lake Creek, west of the area of Everett along Highway 82. Lake Creek then flows into Twin Lakes Reservoir along with several smaller tributaries before eventually flowing into the Upper Arkansas near Balltown, Colorado.

Figure 1. Upper Arkansas River Segment 10 and vicinity. Much of the heavy metals loading throughout the Upper Arkansas River basin is the result of natural geologic conditions and historic mining activities. 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. [3]

**FINAL** The upper Arkansas River watershed has long been impacted by metals contamination from historical mining activities. The Upper Arkansas River originates and runs through an area known as Colorado’s mineral belt. This area has abundant ore deposits and mining activity throughout the area which has occurred for many generations. The area has seen several booms and busts from mining these different ores. There are still many water quality issues associated with natural geologic conditions and historical mining activities throughout this area and the state of Colorado. The Lake Creek watershed displays several of the same water quality concerns that affect neighboring streams and lakes. III. 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. Uses and Standards addressed in this TMDL Date (Cycle Year) of Current Approved 303(d) list: 2008 WBID Segment Description Designated Uses & Impairment Status [4]

**FINAL** Date (Cycle Year) of Current Approved 303(d) list: 2008 WBID Segment Description Designated Uses & Impairment Status Mainstem of Lake Creek and all Aquatic Life Cold 1: Impaired tributaries, lakes and reservoirs Recreation E: Not Impaired COARUA10 from source to Arkansas River Water Supply: Not Impaired (including Twin Lakes reservoir) Agriculture: Not Impaired Table 1. Designated uses and impairment status for Upper Arkansas Segment 10. 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 copper with corresponding non-attainment of pH and dissolved oxygen standards. The specific numeric standards assigned to the Upper Arkansas Segment 10 are contained in the Classifications and Numeric Standards for the Arkansas River Basin, Regulation 32 (WQCC, 2008). In this instance, dissolved copper concentrations, pH, and DO exceed the Aquatic Life Use-based standard intended to protect against short-term, acutely toxic conditions (acute) and longer-term, sub-lethal (chronic) effects. Water Quality Criteria for Impaired Designated Uses WBID

COARUA10

Impaired Designated Use

Applicable Water Quality Criteria and Status

Aquatic Life Cold 1

Dissolved Copper (1) / Not Attained Dissolved Oxygen (1) / Not Attained pH (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 10. 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 usually 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, and/or reproduction (WQCC 2008). IV. PROBLEM IDENTIFICATION To a great extent, heavy metal loading throughout the Arkansas River Watershed has [5]

**FINAL** 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, 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. Segment 10 of the Upper Arkansas River Basin appears on the Colorado 2010 303(d) list for non-attainment of dissolved copper, pH, and DO. The primary source of metals loading in the Lake Creek watershed appears to be the natural weathering process as the area is very high in metal deposits. The mining history in the Upper Arkansas region reflects these natural geologic conditions that exist in this area. There are no active mining operations in the Lake Creek Watershed. Segment 10 is also listed for pH and DO but these parameters are not included in the TMDL calculations. The reason for this omission is that the assessment which led to segment 10 being listed for pH and DO, included data for the year 2000. When the year 2000 data set was removed, segment 10 was found to be in attainment of the pH and DO standards. Several of the samples for the year 2000 data were much lower than the rest of the data and now more than ten years old. These data points helped contribute to the non attainment listing for pH and DO. These low values were not entirely representative of the whole data set, especially for the more recent pH and DO values in Lake Creek. In addition, year 2000 data will most likely not be used in the next assessment of Lake Creek as only the most recent data, generally within the last five to ten years, is preferred when doing the assessments. Looking at the more recent data in Lake Creek, segment 10 is not expected to be listed for pH and DO. Thus it was decided to eliminate the year 2000 data and use only 2001 and newer data to more accurately portray the most current conditions within segment 10. The data used in this TMDL was collected at site 7179A which is located on Lake Creek above Twin Lakes Reservoir. Water quality data was collected by the Water Quality Control Division of the Colorado Department of Public Health and Environment (CDPHE). Since there has been no remediation or ongoing activity in the watershed, this data is assumed to be representative of more recent conditions. The data set for sample site 7179A dates back to January 2001 and continues through June 2004. The data set, as referred to above is graphically represented on the following page. The figure 2 graph shows the dissolved copper concentrations, site specific dissolved copper standard, and the table value-based acute dissolved copper standards for Segment 10. The standards in figure 2 are for the aquatic life based useclassification. The data set contained a total of 21 samples, n=21. [6]

**FINAL**

Figure 2. Dissolved copper concentrations and assigned chronic and acute copper standards in the Upper Arkansas River Segment 10 at site 7179A. (Period of record: Jan. 2001 thru Jun. 2004)

Figure 3. Monthly dissolved Cu concentrations in Segment 10 at site 7179A. Boxes represent the upper and lower quartile values while whiskers represent 5th and 95th percentile values. The red dashes indicate median copper concentrations. (Period of record: Jan. 2001 thru Jun. 2004)

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**FINAL** V. WATER QUALITY GOALS Segment 10 is classified for the Aquatic Life Cold 1, Recreation E, Water Supply and Agriculture uses. The Aquatic Life Use standards are site specific for the chronic dissolved copper standard and table value based for the acute standards which is calculated by using the hardness-based equations specified in Regulation 32. The goal of this TMDL is attainment of the site specific dissolved copper standard as characterized as the 85% ambient concentration, and the table value based acute standard applied on a discrete sample basis. Attainment of the assigned standards 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 January 2001 through December 2007.

Figure 4. Box and whisker plots for median monthly flow on Lake Creek above Twin Lakes. [8]

**FINAL** Boxes represent upper and lower quartile values while whiskers represent 5th and 95th percentile values. Red dashes indicate median flows. (Period of Record: Jan. 2001 thru Dec. 2007) Ambient Water Quality Ambient Chronic Acute Mean Dissolved Copper Dissolved Dissolved Hardness ug/L Copper Copper th Month mg/L (85 percentile) Standard ug/L Standard ug/L 7.26 January 57 8 12.1 N/A February 57 8 24.5 7.78 March 57 8 36.8 4.73 April 41 8 12.7 2.81 May 19 8 7.0 2.81 June 24 8 11.4 4.86 July 43 8 9.4 4.46 August 46 8 8.3 7.26 September 52 8 7.0 7.78 October 56 8 6.0 2.25 November 38 8 14.4 7.52 December 54 8 7.0 Table 3. Average hardness, chronic stream standards, and the lowest monthly acute standard (the most protective acute value) for 303(d) listed segment 10 from Jan. 2001 through Jun.2004, n=21. The table value acute dissolved copper standard was calculated with the data set for site 7179A. There were 13acute exceedances out of 21 samples for a 62% exceedance rate of the acute table value based standard. The exceedances of the acute dissolved copper standard occurred in all parts of the year. Chronic exceedances are greatest during periods of low flow with the highest levels occurring in February and March. There are four months (May, Sept, Oct, and Dec) when segment 10 is in attainment of the site specific chronic dissolved copper standard. Climate data for the area is collected at the Twin Lakes weather station. The weather station is located near Upper Arkansas segment 10 and characterizes climatic conditions in the Upper Arkansas watershed. Climate data for this station was collected from August 1949 through August 2009. A summary of the climate data is provided below: Average annual precipitation (in.): 9.59 Month of highest precipitation: August (1.52 in.) Month of lowest precipitation: January/February (0.47 in.) Average annual snowfall (in.): 45.3 Average annual temperature: 38.8°F Month of lowest average temperature: February (4°F) [9]

**FINAL** Month of highest average temperature: July (73.5°F) (source: www.wrcc.dri.edu ) VI. SOURCE ANALYSIS Lake Creek is a major tributary to the upper Arkansas River located approximately 15 miles south of Leadville Colorado. Segment 11, the South Fork Lake Creek, which is listed for pH, aluminum, cadmium, copper and zinc, drains into this major tributary. The Colorado Geological Survey (CGS now DRMS) conducted a NASA-funded survey of the Lake Creek watershed (Segment 11) in Spring 2002 through Fall 2003. The survey used remote sensing to map the mineralogy related to water quality within the hydrothermally altered watershed and to identify the relative contributions of natural and anthropogenic sources of metals contamination (Bird and Sares et al., 2003. http://dept.ca.uky.edu/asmr/W/Full%20Papers%202005/0071-BirdCO.pdf.). Historic mining in the area was limited to only a few small claims, which were known for relatively low producing but high-grade gold deposits, none of which are known to discharge to the watershed. Production generally came from small, Laramide gold veins in Precambrian igneous rocks (Moran and Wentz, 1974). The watershed is an area of widespread hydrothermal alteration that includes pyrite, various clay minerals, iron oxides, and other minerals associated with acid-sulfate alteration. Springs discharging from this zone typically have pH below 3 and contain high concentrations of metals, including aluminum and iron exceeding 200 mg/L, copper up to 10 mg/L, and sulfate up to 29,000 mg/L (Bird and Sares et al., 2003). Hence, the area provides a unique opportunity to study the impacts from acid rock drainage (ARD) derived from primarily natural sources with only minimal anthropogenic disturbance (Bird and Sares et al., 2003). Previous survey work has identified the South Fork as the primary source of acid and metal loadings in the Lake Creek basin. Significant dilution from the North Fork greatly reduces downstream metals concentrations. Oxidized and weatherized rock formations leave exposed mineral veins and deposits of ore which can reach water sources. These decomposed rock formations are known as gossans. These gossans are often visible to the human eye from far away due to the intense oxidation. Red Mountain in this area is named because of this gossan effect making the mountain top look red. Snowmelt and groundwater fed springs flow through these areas and carry high metal concentrations and very low pH values. Figure 5. on page 11 includes a Google satellite image of gossans in the Lake Creek Watershed Two relatively discreet areas have been identified as the major sources of acid and metals contamination within the South Fork drainage basin; Peekaboo Gulch and an unnamed tributary to the east fork of Sayres Gulch. The headwaters of Peekaboo Gulch include diffuse seepage from the base of Red Mountain. As the name implies, Red Mountain is rich in iron and trace metal sulfides resulting in the production of acidic, metal laden waters. Although dry mine shafts and small tailings areas are present in the area, drainage from Red Mountain appears to be the primary source of metals to Peekaboo Gulch. Sayres Gulch has been identified as the major source of acid and metals loadings within the Lake Creek drainage basin. The source is a small [10]

**FINAL** tributary collecting seepage from a highly mineralized ridge located approximately 4/5 mile up the East Fork Sayres Gulch.

Figure 5. Google image of Sayres Gulch/South Fork Lake Creek watershed showing gossans in the area. VII. TMDL ALLOCATION Allocation Methodology As noted above, increased levels of copper over the TVS are a result of natural geologic conditions and historic mining activities in the area. In order to attain the chronic and acute for copper, load allocations have been assigned to reach the goal of this TMDL. The loading reductions have been assigned to non-permitted discharges related to natural geologic conditions.

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 [11]

**FINAL** 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 are no permitted dischargers on segment 10. As such, there are no identified waste load allocations for this TMDL. While there are a few small mine claims in the watershed, no discharge associated with these features has been documented. If the Water Quality Control Division documents drainages in the future, this TMDL will be revisited. Load Allocation Hydrothermally altered natural background copper concentrations are considered in the LA portion of this TMDL. 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 explicit MOS of 10% was used in the development of this TMDL.

Ambient Stream Conc. Month (lbs/day)

TMDL Allowable Load (lbs/day)

10% MOS

TMDL with 10% MOS, lbs/day

WLA LA (lbs/day) (lbs/day)

% Reduction needed to attain chronic std.

% Reduction needed to attain acute std.

JAN

1.05

0.63

0.06

0.57

0.00

0.57

40%

46%

FEB

1.68

0.55

0.06

0.49

0.00

0.49

71%

N/A

MAR

3.35

0.71

0.07

0.64

0.00

0.64

80%

81%

APR

2.50

0.93

0.09

0.84

0.00

0.84

43%

66%

MAY

16.97

6.81

0.68

6.13

0.00

6.13

0%

64%

JUN

46.59

11.49

1.15

10.34

0.00

10.34

37%

78%

JUL

11.77

6.09

0.61

5.48

0.00

5.48

23%

53%

AUG

5.52

2.98

0.30

2.68

0.00

2.68

13%

51%

SEP

2.17

2.25

0.23

2.03

0.00

2.03

0%

7%

OCT

1.31

1.70

0.17

1.53

0.00

1.53

0%

0%

NOV

2.90

0.45

0.05

0.41

0.00

0.41

50%

86%

DEC

0.88

0.94

0.09

0.85

0.00

0.85

0%

3%

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**FINAL** Table 4. TMDL allocations for Segment 10 of the Upper Arkansas River. TMDL allocations are based on the chronic site specific standard except in cases where the acute standards will not be met. In months (March thru January) where the acute standard is not met, reductions were set to meet the acute table value based standards. The most conservative load will dictate monthly reductions for this TMDL and are highlighted in bold letters. Because of the limited data set for the Upper Arkansas River Segment 10, a more complete data set would be required in order to provide a more robust TMDL analysis for this segment. Since there are no permitted discharges to this segment, the uncertainty in the TMDL predictions will not affect any permitted point source discharges. The range in reductions for the TMDL allocations is from the lowest (0%) in the month of October to the highest (86%) in the month of November. The reductions calculated in table 4 will ensure that Lake Creek will attain the dissolved copper standard of 8 ug/L and the acute table value based standard. As mentioned earlier, Segment 10 is also listed for pH and DO but these parameters are not included in the TMDL calculations. The reason for this omission is that the assessment which led to segment 10 being listed for pH and DO, included data for the year 2000. When the year 2000 data set was removed, segment 10 was found to be in attainment of the pH and DO standards. In addition, year 2000 data will most likely not be used in the next assessment of Lake Creek as only the most recent data, generally within the last five to ten years, is preferred when doing the assessments. Looking at the more recent data in Lake Creek, segment 10 is not expected to be listed for pH and DO. VIII. RESTORATION PLANNING AND IMPLEMENTATION PROCESS Water Quality Improvements in the Watershed There are no known improvements in the Lake Creek watershed or any known plans for improvements in the watershed at this time. Monitoring In order to ensure that this TMDL is adequately protective of the segment, additional monitoring is necessary. Goal The goal of this TMDL is to ensure that Segment 10 is in attainment of the chronic and acute standards for dissolved copper. Attainment of the site specific chronic standard for dissolved copper will not always ensure that the acute TVS for dissolved copper is met, so reductions were set in table 4 that will ensure both chronic and acute standards are met. Attainment of the acute TVS and chronic site specific standard for dissolved copper will help protect the beneficial uses of Segment 10, including the Aquatic Life use. VIIII. Public Involvement The public has the opportunity to be involved in the Water Quality Control Commission [13]

**FINAL** (WQCC). 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 for the month of July so that the public would have an opportunity to comment on this TMDL. No comments in regards to this TMDL were received.

X. References WQCC 2010: 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 9, 2010. 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. Colorado Water Quality Control Division In Cooperation with the Colorado Division of Wildlife: Lake Creek Nonpoint Source Study, January 1991. Bird, D.A. et. al, Naturally occurring acid rock drainage in Colorado's Lake Creek Watershed. 2005 National Meeting of the American Society of Mining and Reclamation, June 19-23, 2005. Publisher: ASMR, 3134 Montavesta Rd., Lexington, KY 40502. http://dept.ca.uky.edu/asmr/W/Full%20Papers%202005/0071-Bird-CO.pdf.

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