UNITED STATES E ~ O N M E ~ ~PROTECTION A L AGENCY R E G I ~ N8 1595 WYI$KOOP DENVER,CO 80202-1129 Phone 800- 27-8917
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Mr. Steve Gunderson, Director Wabr Quality Control Division Colorado Deparbnent of Public Health and ~nvir0nrnen.t 4300 Cherry Creek Drive South Denver, Colorado 80246- 1530
Silver lreek; COSlD009
Dear Mr. Gunderson: We have completed our review of the total maxi*um daily loads (TMDLs) as submitted by your office for the waterbodies listed in the enclosure to this fetter. In accordance with the Clean Water Act (33 U.S.C. 125 1 et. seq.), we approve all aspects of Th4DFs as developed for certain pollutants in water quality limited waterbodies as described in Section 303(d)(1). Based on our review, we feel the separate are adequately addressed, taking into TMDL elements for the pollutants listed in the edclosed considemtion seasonal variation and a margin of safety.
Thank you for submitting these W L s for our dview and approval. If you have any questions, she can be reached at (303) 3 12-6947. the most knowledgeable person on my staff is
Administrator &d Remediation I
Enclosures
Paper
TOTAL MAXIMUM DAILY LOAD ASSESSMENT Geneva Creek Segment COSPUS05b Park County, Colorado
TMDL SUMMARY
Waterbody Name/Segment Number
Mainstem of Geneva Creek from the confluence with Scott Gomer Creek to the confluence with the North Fork of the South Platte River; all tributaries of Geneva Creek including lakes, reservoirs and wetlands from source to confluence with the North Fork of the South Platte River. / COSPUS05b
Pollutant/Condition Addressed
Cu, Zn
Affected Portion of Segment
Use Classification/Waterbody Designation
Geneva Creek from Scott Gomer Creek to the confluence with North Fork of the South Platte River Agriculture Aquatic Life Cold 1 Recreation 1a Water Supply
Waterbody Antidegradation Designation
reviewable
Water Quality Target
Attainment of water quality standards.
TMDL Goal
Attainment of water quality standards.
EXECUTIVE SUMMARY Geneva Creek, segment COSPUS05b, has been identified as water-quality limited for dissolved copper and zinc on the 1998 and subsequent 303(d) Lists, as approved by the Colorado Water Quality Control Commission. There are no readily apparent point source discharges of pollutants, either permitted or unpermitted, to this segment. This TMDL derives load allocations for dissolved copper and zinc to demonstrate the load reduction necessary for dissolved copper and zinc in order to attain the currently adopted standards. Because the sources of pollutants in this watershed are predominately natural, this TMDL does not contain an implementation plan to attain standards.
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Total Maximum Daily Load Assessment for Geneva Creek, COSPUS05b
1.0 INTRODUCTION Section 303(d) of the federal Clean Water Act requires states to identify water bodies that are water quality impaired. Water quality impaired segments are those water bodies or stream segments which are not fully attaining one or more assigned use classification or standard. These segments are currently identified on the Colorado 2006 303(d) List. Once listed, the State is required to quantify the amount of a specific pollutant that a listed water body can assimilate without exceeding applicable water quality standards. This maximum allowable pollutant quantity is referred to as the Total Maximum Daily Load ("TMDL"). The TMDL is comprised of the Load Allocation ("LA"), which is that portion of the pollutant load attributed to natural background or the nonpoint sources, the Waste Load Allocation ("WLA"), which is that portion of the pollutant load associated with point source discharges, and a Margin of Safety ("MOS"). The TMDL may also include an allocation reserved to accommodate future growth. The TMDL may be expressed as the sum of the LA, WLA, and 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 an 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”). 1.1 Segment Description Geneva Creek rises in Geneva Basin near the Continental Divide in Clear Creek County and flows southeasterly through Park County towards its confluence with the South Platte River at Grant, Colorado. Geneva Creek has been split into two segments for regulatory purposes. The upper segment (Upper South Platte segment 5a) is from the source of Geneva Creek to the confluence with Scott Gomer Creek, and is roughly 9 miles in length. The lower segment (Upper South Platte segment 5b) is from Scott Gomer Creek to the confluence with the South Platte River, and is roughly 4 miles in length. A map of the Geneva Creek watershed is located in Appendix A. The Geneva Creek watershed lies within hydrothermally altered terrain associated with the Montezuma Stock. The Montezuma Stock and associated hydrothermal ore deposits were heavily mined on the western side of the Continental Divide in the Snake River and Peru Creek drainages. Mining on the eastern side of the Continental Divide in areas dominated by Montezuma Stock alteration appears to be minimal (CGS 2000). 1.2 Discharge Permits and Property Ownership There are currently no Colorado Discharge Permit System (CDPS) or National Permit Discharge Elimination System (NPDES) permits that discharge to Geneva Creek or its tributaries. The majority of the Geneva Creek Basin is owned by the U.S. Forest Service as part of the Pike National Forest, therefore it is unlikely that any new discharges will occur in the next twenty years. The Iron Fen area, located in the headwaters of Geneva Creek (segment COSPUS05a) and
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Total Maximum Daily Load Assessment for Geneva Creek, COSPUS05b
discussed in Section 4.0, is owned by Clear Creek County and is registered as a Colorado State Natural Area with the Department of Natural Resources. 2.0 Problem Identification Copper and zinc are the pollutants of concern considered in this TMDL. This TMDL addresses Upper South Platte segment 5b, which is from Scott Gomer Creek to the confluence with the South Platte River. The 1998 and the 2002 303(d) lists rate the segment priority as “High”, and has remained “High” since. However, the Division has not acted on this listing until 2005 because no significant anthropogenic point sources have been identified in the watershed that could be addressed through an NPDES or CDPS permit. 2.1 Water Quality Goals and Targets The water quality targets and goals for this TMDL is attainment of the current dissolved copper and zinc water quality standards. 3.0 Water Quality Standards The following table lists the water quality standards for Geneva Creek segment 5b from the Water Quality Control Commission’s Regulation No. 36. Table 3.1. Water quality standards for Upper South Platter River segment 5b (COSPUS05b). Stream Segment Description 05b. Mainstem of Geneva Creek from the confluence with Scott Gomer Creek to the confluence with the North Fork of the South Platte River; all tributaries of Geneva Creek including lakes, reservoirs and wetlands from source to confluence with the North Fork of the South Platte River.
Classification Agriculture Aq Life Cold 1 Recreation 1a Water Supply
Physical and Biological
INORGANICS mg/l
E.Coli=126/100ml B=0.75 F.Coli=200/100ml Cl=250 D.O.=6.0mg/l Cl2(ac)=0.019 D.O.(sp)=7.0mg/l Cl2(ch)=0.011 pH=6.5-9.0 CN=0.005 NH3(ac)=TVS NH3(ch)=0.02 NO2=0.05 NO3=10 S=0.002 SO4=WS
METALS ug/l Ag(ac)=TVS Hg(ch)=0.01(Tot) Ag(chtr)=TVS Mn(ac)=TVS As(ch)=100(Trec) Mn(ch)=WS(Dis) Cd(actr)=TVS Mn(ch)=TVS Cd(ch)=TVS Ni(ac)=TVS CrIII(ac)=TVS Ni(ch)=TVS CrIII(ch)=TVS Pb(ac)=TVS CrVI(ac)=TVS Pb(ch)=TVS CrVI(ch)=TVS Se(ac)=TVS Cu(ac)=TVS Se(ch)=TVS Cu(ch)=TVS Zn(ac)=TVS Fe(ch)=WS(Dis) Zn(ch)=TVS Fe(ch)=1000(Trec)
3.2 Hydrology Geneva Creek expresses the hydrologic characteristics of a high-altitude, snowmelt-dominated stream, with peak runoff occurring in June. The U.S. Geological Survey operated a hydrologic gage on Geneva Creek near the town of Grant from water-years 1994 through 1997. The drainage area at the USGS gage for Geneva Creek is 74.6 square miles, and the gage is at 8,760 feet above sea level. Table 1 and Figure 1 show the hydrologic characteristics of Geneva Creek.
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Total Maximum Daily Load Assessment for Geneva Creek, COSPUS05b
Table 1: Hydrologic characteristics of Geneva Creek (USGS gage #06705500).
Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
25th Percentile Median 75th Flow Flow Percentile (cfs) (cfs) (cfs) Count 12.1 11.0 12.0 13.0 10.8 9.6 12.0 12.0 13.6 12.0 13.0 15.0 18.2 14.0 17.0 22.0 101.4 35.5 65.0 174.5 315.2 211.5 267.5 374.5 183.8 107.0 148.0 223.5 77.1 36.5 82.0 109.5 38.5 29.0 38.5 45.0 24.8 20.0 24.0 27.0 19.1 16.8 20.0 21.0 16.5 14.0 16.0 18.0
Mean Flow (cfs)
93 85 93 90 93 90 93 93 90 93 90 93
Figure 1: Hydrologic characteristics of Geneva Creek (USGS gage #06705500).
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Total Maximum Daily Load Assessment for Geneva Creek, COSPUS05b
3.3 Ambient Water Quality Copper The Division took 23 water quality samples in Geneva Creek between March, 1999 and June, 2004. Of those 23 samples, only 3 were above the detection limit. Two of those samples with quantifiable results exceed both the acute and chronic standard. Based upon the Division’s 2006 303(d) Listing Methodology, Geneva Creek is not considered impaired with respect to the assigned copper standard. However, a copper TMDL has been developed and is included. Zinc The Division took 23 water quality samples in Geneva Creek between 3/1999 and 6/2004. Table 2 shows the hardness, dissolved zinc concentrations in Geneva Creek, and the chronic standard. Of the 23 samples, only 7 had water quality attaining the chronic standard. Sixteen samples exceed the acute standard, calculated using the sample hardness. Table 2: Dissolved zinc concentrations in Geneva Creek with the correlating standard. Station ID 5799 5799 5799 5799 5799 5799 5799 5799 5799 5799 5799 5799 5799 5799 5799 5799 5799 5799 5799 5799 5799 5799 5799
Station Name GENEVA CR. @ MOUTH GENEVA CR. @ MOUTH GENEVA CR. @ MOUTH GENEVA CR. @ MOUTH GENEVA CR. @ MOUTH GENEVA CR. @ MOUTH GENEVA CR. @ MOUTH GENEVA CR. @ MOUTH GENEVA CR. @ MOUTH GENEVA CR. @ MOUTH GENEVA CR. @ MOUTH GENEVA CR. @ MOUTH GENEVA CR. @ MOUTH GENEVA CR. @ MOUTH GENEVA CR. @ MOUTH GENEVA CR. @ MOUTH GENEVA CR. @ MOUTH GENEVA CR. @ MOUTH GENEVA CR. @ MOUTH GENEVA CR. @ MOUTH GENEVA CR. @ MOUTH GENEVA CR. @ MOUTH GENEVA CR. @ MOUTH
Date 24-Mar-99 21-Apr-99 02-Jun-99 24-Jun-99 09-Aug-99 20-Sep-99 25-Oct-99 22-Nov-99 15-Dec-99 24-Jan-00 12-Sep-02 08-Oct-02 18-Nov-02 21-Jan-03 10-Mar-03 13-May-03 18-Jun-03 14-Jul-03 09-Sep-03 22-Dec-03 15-Mar-04 29-Apr-04 16-Jun-04
Hardness mg/l 49 44 18 16 21 25 23 29 30 32 35 35 34 32 31 30 20 24 26 34 34 29 95
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Zn ug/l 330 280 10 10 29 52 10 64 77 84 72 83 64 22 17 48 32 49 51 95 75 53 38
Chronic Standard 64.5 58.9 27.6 25.0 31.5 36.5 34.0 41.4 42.6 45.0 48.5 48.5 47.4 45.0 43.8 42.6 30.2 35.3 37.7 47.4 47.4 41.4 113.1
Exceed/Attain Chronic Standard Exceed Exceed Attain Attain Attain Exceed Attain Exceed Exceed Exceed Exceed Exceed Exceed Attain Attain Exceed Exceed Exceed Exceed Exceed Exceed Exceed Attain
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Total Maximum Daily Load Assessment for Geneva Creek, COSPUS05b
4.0 Source Analysis Point Sources There are no NPDES or CDPS permitted point source discharges in the Geneva Creek Basin. The majority of the Geneva Creek Basin is owned by the U.S. Forest Service as part of the Pike National Forest, therefore it is unlikely that any new discharges will occur in the next twenty years. Topographical maps from the USGS show numerous mining features in the basin at high elevation. No further information was found about these features. Division staff toured the area in the summer of 2005. While legacy mining features are present in the upper Geneva Creek basin, no discharges, either from draining adits or mine wastes affecting surface drainages, were observed. The Iron Fen area, discussed below, is owned by Clear Creek County and is registered as a Colorado State Natural Area with the Department of Natural Resources. Non-Point and Natural Sources The most significant natural geochemical feature in the Geneva Creek Basin is the Geneva Creek Iron Fen. An Iron Fen a unique wetland feature where acidic metal laden groundwater comes to the surface and produces a reddish substrate of precipitated iron minerals on the bed of the wetland. Due to its ecological significance, the property surrounding the Geneva Creek Iron Fen, approximately 100 acres, was purchased by the Clear Creek County Open Space Commission. The Iron Fen is situated in and gives rise to the headwaters of Geneva Creek. More information about the Geneva Creek Iron Fen can be found at the Clear Creek County Open Space Commission’s website (http://www.co.clearcreek.co.us/OSWebsite/GenevaCreek.htm). The headwaters of Geneva Creek are in hydrothermally altered geologic terrain associated with the Montezuma Stock. This type of geologic terrain produces acid rock drainage, which is naturally occurring degradation of waters by the contact of water with oxidizing sulfide minerals. These two factors are the source of metals and acidity in Geneva Creek.
6.0 TMDL ALLOCATION Total Maximum Daily Loads ("TMDL") A TMDL is comprised of the Load Allocation ("LA"), which is that portion of the pollutant load attributed to natural background or the nonpoint sources, the Waste Load Allocation ("WLA"), which is that portion of the pollutant load associated with point source discharges, and a Margin of Safety ("MOS"). The TMDL may also include an allocation reserved to accommodate future growth. The TMDL may be expressed as the sum of the LA, WLA and MOS.
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Total Maximum Daily Load Assessment for Geneva Creek, COSPUS05b
TMDL = WLA + LA + MOS TMDL = Sum of Waste Load Allocations + Sum of Load Allocations + Margin of Safety Waste Load Allocations "(WLA") There are no identified waste load allocations for this TMDL. Load Allocations ("LA") All other sources that were examined are considered non point sources and therefore are accountable to load allocations. Margin of Safety ("MOS") The MOS used in the TMDL analysis is implicit and resides in the conservative assumptions utilized in the calculations and management response to removal of the source materials, and post-remediation water quality monitoring that will be performed. The conservative assumptions used in the analysis include the use of the 85th percentile of the data in establishing ambient conditions. Mean hardness was used in calculation of hardness based TVS. The TMDL addresses worst case conditions in terms of metals concentrations. Additionally, the use of a mean hardness value represents a conservative element. Finally, the TMDL is based on an estimated stream flow which is considerably lower than that recorded by the WQCD during low flow conditions. This will tend to overestimate the loading reductions. The TMDL equation becomes the following: TMDL = Sum of Load Allocations (LA) LA (lbs/day) = Water Quality Standard, TVS (ug/l) x Flow (cfs) x 0.0054
6.1 TMDL FOR DISSOLVED ZINC For the dissolved zinc TMDL, a 10% Margin of Safety was included in the TMDL. Table 3 lists the TMDL for Geneva Creek. The entire TMDL is Load Allocation or Non-Point Source pollution.
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Total Maximum Daily Load Assessment for Geneva Creek, COSPUS05b
Table 3: Total Maximum Daily Load for dissolved zinc for Geneva Creek with a 10% Margin of Safety. Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Median Flow 12.0 12.0 13.0 17.0 65.0 267.5 148.0 82.0 38.5 24.0 20.0 16.0
Hardness CaC03 Zn Std mg/l ug/l 32 45 36 50 40 54 44 59 30 43 18 28 24 35 21 31 30 43 29 41 32 44 30 43
Zn TMDL lbs/day 2.6 2.9 3.4 4.9 13.5 35.9 25.4 12.5 8.0 4.8 4.3 3.3
Current Zn ug/l 53 113 174 280 48 14 22 29 62 42 64 77
Current Percent Zn Load Load Load lbs/day Reduction Reduction 3.4 0.8 24% 7.3 4.4 60% 12.2 8.7 72% 25.7 20.8 81% 16.8 3.4 20% 20.2 0.0 0% 17.2 0.0 0% 12.8 0.3 2% 12.9 4.9 38% 5.4 0.6 10% 6.9 2.6 38% 6.7 3.3 50%
6.2 TMDL FOR DISSOLVED COPPER For the dissolved copper TMDL, no Margin of Safety was included in the TMDL because the segment is currently attaining the copper standard. Table 4 documents the copper TMDL for Geneva Creek. The entire TMDL is Load Allocation or Non-Point Source pollution. Table 4: Total Maximum Daily Load for dissolved copper for Geneva Creek with no Margin of Safety. Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Median Flow 12 12 13 17 65 267.5 148 82 38.5 24 20 16
Hardness CaC03 Cu Std mg/l ug/l 32 3.4 36 3.7 40 4.1 44 4.4 30 3.2 18 2.1 24 2.6 21 2.4 30 3.2 29 3.1 32 3.4 30 3.2
Cu TMDL lbs/day 0.22 0.24 0.29 0.41 1.12 2.99 2.11 1.05 0.67 0.40 0.37 0.28
Current Cu ug/l 2 2 2 2 2 2 2 2 2 2 2 2
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Current Load Percent Cu Load Reduction Load lbs/day lbs/day Reduction 0.1296 0 0% 0 0.1296 0% 0 0.1404 0% 0 0.1836 0% 0 0.702 0% 0 2.889 0% 0 1.5984 0% 0 0.8856 0% 0 0.4158 0% 0 0.2592 0% 0 0.216 0% 0 0.1728 0%
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Total Maximum Daily Load Assessment for Geneva Creek, COSPUS05b
7.0 RESTORATION PLANNING AND IMPLEMENTATION PROCESS There is no known restoration planning for the Geneva Creek watershed other than the protection of the Geneva Creek Iron Fen by Clear Creek County Open Space. There is no planned removal of zinc or copper loading at present. 8.0 PUBLIC INVOLVEMENT The section of the Geneva Creek from Scott Gomer Creek to the confluence with the North Fork of the South Platte River, segment 5b, was included on the 1998 303(d) list of impaired waters in Colorado based upon water quality data. The development of the 303(d) list is a public process involving solicitation, from the public, of candidate waterbodies, formation of a technical review committee comprised of representatives of both the public and private sector, and a public hearing before the Colorado Water Quality Control Commission. Public notice is provided concerning both the solicitation of impaired waterbodies and the public hearing. The TMDL itself is subject of an independent public process. The TMDL was made available for public review and comment during a 30 day public notice period in May, 2006. Notice was provided in the Colorado Water Quality Information Bulletin. No public comments were received. 9.0 References Matthew A. Sares, Daryl L. Gusey, and John T. Neubert, Abandoned Mines and Naturally Occurring Acid Rock Drainage on National Forest System Lands in Colorado, Colorado Geological Survey, 2000.
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Total Maximum Daily Load Assessment for Geneva Creek, COSPUS05b
Appendix A: Map of the Geneva Creek Watershed.
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