UNITED STATES ENVIRONMENTAL PROTECTION AGENCY REGION 8
999 ISm STREET
- SUITE 300
DENVER. CO 80202-2466
J. David Holm, Director Water Quality Control Division Colorado Department of Public Health and ~ n & n n 4300 Cherry Creek Dr. S. Denver, Colorado 80246-1 53 0
Re:
L Approvals Straight Creek (xedimenf ) hnos4uito Creek (metals) $an Miguel River (sedimnf )
V
I
Dear Mr. Holm:
We have completed our review of the total m&um daily loads (TMDLs) as submitted by y w office for the waterbodies listed in the eaclo& to this letter. In accordance with the Clean Water Act (33 U.S.C. 1251 e t seq.), we approvk all aspects of the TMDLs as developed for the water quality limited waterbodies as described Section 303(d)(l). Based on our review, we fee1 the separate TMl?L elements listed in the enclosed review table adequately address the pollutants of concern, takhg into consideration seasonal variation and a margin of safety. Please find enclosed a detail& review of these TMDLs.
Thank you for your submittal. If you have an4 questions concerning this approval, feel free to contact Kathryn Hernandez of my M a t 303012-6101.
Assistant ~ e ~ i o nAdministrator al Office of Emsyhms Protection and Remediation
Enclosure
Colorado Water Quality Control Division
San Miguel River
TOTAL MAXIMUM DAILY LOAD ASSESSMENT San Miguel River Segment 3b Sediment San Miguel County, Colorado TMDL SUMMARY Mainstem of the San Miguel River Waterbody Name/Segment Number From Marshall Creek to the South Fork of the San Miguel, COGUSM03b Sediment Pollutant/Condition Addressed All Affected Portion of Segment Aquatic Life Cold 1, Recreation 1 Use Classification Use Protected Waterbody Designation 30% reduction of sediment from early Water Quality Target spring runoff Attainment of narrative sediment standard TMDL Goal EXECUTIVE SUMMARY Section 303(d) of the federal Clean Water Act requires states to identify water bodies or stream segments that are water quality limited on the 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 violating applicable water quality standards and to apportion that allowable quantity among the different pollutant sources. This maximum allowable pollutant quantity is referred to as the Total Maximum Daily Load (TMDL). The San Miguel River from Marshall Creek to the South Fork of the San Miguel was included on the Colorado 1998 303(d) List, as partially supporting aquatic life, due to high levels of dissolved cadmium, manganese, zinc and sediment. The focus of this TMDL is on the aquatic life impairments caused by high siltation from urban runoff. The goal of this TMDL is to reduce sediment loads from the stream substrate to provide better habitat for aquatic life populations. The principal source of sediment is the runoff entering the river through the Alder Street culvert. The critical period TMDL for the stream is based on a LA of 2 kg/day (4.4 lbs/day) total sediment from the Alder Street culvert and a LA of 12 kg/day (26 lbs/day) total sediment from the other nonpoint and background sources and an implicit MOS. The annual TMDL for the River is 14 kg/day (31 lbs/day) total sediment.
Sediment TMDL
Page 1
June 15, 2000
Colorado Water Quality Control Division
I.
San Miguel River
INTRODUCTION
Section 303(d) of the federal Clean Water Act requires states to identify water bodies or stream segments that are water quality limited. Those water quality limited segments currently identified in Colorado are identified on the 1998 303(d) List. Water quality limited segments are those water bodies or stream segments which, for one or more assigned use classifications or standards, the classification or standard is not fully achieved. Once listed, the State is required to quantify the amount of a specific pollutant that a listed water body can assimilate without violating applicable water quality standards and to apportion that allowable quantity among the different pollutant sources. 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. The San Miguel River from Marshall Creek to the South Fork of the San Miguel (Segment COGUSM03B, or 3b) was included on the Colorado 1998 303(d) List, as partially supporting aquatic life, due to high levels of dissolved cadmium, manganese, zinc and sediment (WQCC 1998A). The focus of this TMDL is on the aquatic life impairments caused by high siltation from urban runoff. The metals loading will be addressed in a later TMDL. The goal of this TMDL is to reduce sediment loads from the stream substrate to provide better habitat for aquatic life populations. Site Description: The San Miguel River is a third order stream draining the Telluride Valley floor and surroundings. It has an approximate low flow discharge of 12 cubic feet per second (cfs) and an approximate high flow of 400-500 cfs, with a large width to depth ratio and poor eroding bank conditions. The Town of Telluride is approximately one square mile in area; it sits on an alluvial plane that slopes southward from an elevation of 9,200 feet to 8,700 feet (See Figure 1). The entire western and central portions of Town are largely on the alluvial fan of Cornet Creek and the eastern portions are constructed on colluvial slopes derived from erosion of upslope sandstone layers: Cutler, Dolores and Entrada formations. The alluvial fan has relatively low content of particles finer than sand (mostly gravels with sand and sandy loam) but the colluvial slopes consist of high clays and silt. Tributaries to the San Miguel drain several historic mining districts; however, no active mining is currently underway in the region. The Idarado Mine Superfund site is located in the upper basin and is currently undergoing remedial activities. The population of the Town of Telluride varies seasonally due to the ski industry. Higher automobile traffic is observed through Town during the winter ski season.
Sediment TMDL
Page 2
June 15, 2000
Colorado Water Quality Control Division
San Miguel River
Permitted dischargers to Segment 3b include the Town of Telluride Regional WWTP (permit number CO-0041840) that discharges to the San Miguel River below Society Turn and Telecam-Lawson Hill (permit number CO-0044792) that discharges to the San Miguel above the confluence with the South Fork of the San Miguel. In addition, the Town of Telluride Water Treatment Plant (permit number CO-0039527) discharges to Cornet Creek in Segment 2. II.
WATER QUALITY STANDARDS
Table 1 presents the water quality classifications and standards for Segment 3b. This information was extracted from the Classifications and Numeric Standards for Gunnison and Lower Dolores River Basins, Water Quality Control Commission Regulation No. 35, effective date: January 30, 1999 (WQCC 1999A). Segment 3b is listed as impaired on the 303(d) List for cadmium, manganese, zinc and sediment. This TMDL addresses the sediment impairment. Segment 3b is currently classified as an Aquatic Life Cold 1, Recreation 1 stream. The Colorado Water Quality Control Commission (WQCC) has adopted site specific standards and temporary modifications. These standards are as follows: Table 1 Summary of Water Quality Standards for Segment 3b Physical and Biological
D.O.=6.0 mg/L D.O.(sp)=7.0 mg/L pH=6.5-9.0 F.Coli=200/100 ml
Inorganic mg/L
NH3(ac)=TVS NH3(ch)=0.02 Cl2(ac)=0.019 Cl2(ch)=0.011 CN=0.005
S=0.002 B=0.75 NO2=0.0 5
Metals µg/L
As(ac)=50(Trec) Cd(ac)=TVS(tr) CrIII(ac/ch)=TVS CrVI(ac/ch)=TVS Cu(ch)=TVS
Fe(ch)=1000Trec Pb(ch)=TVS Mn(ch)=1000 Hg(ch)=0.01(tot) Ni(ac/ch)=TVS
Temporary Modifications mg/L Se(ac/ch)=TVS Ag(ac)=TVS Ag(ch)=TVS(tr) Zn(ch)=190
Cd(ch)=2.13 Mn(ch)=462 Zn(ch)=640 effective until 6/30/2002
The title of Table 1 refers to the segment number. The segment is also identified by it’s Waterbody Identification (WBID), COGUSM03b, or “CO = Colorado, GU = Gunnison River Basin (Major basin), SM = San Miguel River Basin (Sub-basin), 03b = Segment Number”. The segment does not have a designation, meaning antidegradation reviews are required. The final column lists the temporary modifications adopted for the segment. Segment 3b has temporary modifications to the cadmium, manganese and zinc standards set at ambient levels and expire on 6/30/2002. Many of these site specific standards are based on the Table Value Standards (TVS) which are provided in Appendix A.
Sediment TMDL
Page 3
June 15, 2000
Colorado Water Quality Control Division
San Miguel River
Colorado has not adopted numeric criteria for parameters related to sediment accumulation. Instead, the Basic Standards and Methodologies for Surface Waters, Regulation No. 31 (WQCC 1999B) includes a narrative standard for sediment which specifies the following: “Except where authorized by permits, BMPs, 401 certifications, or plans of operation approved by the Division or other applicable agencies, state surface waters shall be free from substances attributable to human-caused point source or nonpoint source discharge in amounts, concentrations or combinations which...can settle to form bottom deposits detrimental to the beneficial uses.” Colorado has developed interim guidance on interpretation and application of the narrative sediment standard. The WQCC Policy 98-1, Provisional Implementation Guidance for Determining Sediment Deposition Impacts to Aquatic Life in Streams and Rivers (WQCC 1998B) was developed in 1998 by the Colorado Water Quality Control Division (WQCD) in conjunction with the Colorado Sediment Task Force. The guidance sets forth an approach to assessment of sediment impacts to a stream based on a reference stream and condition. The study stream is evaluated for habitat and biological impairment in comparison to a reference stream. Attainment of the narrative sediment standard is assessed by the study stream’s habitat and biological quality percentage of the reference stream quality. The guidance was reviewed by the WQCC at their May 2000 hearing and extended for another two years. The Colorado Sediment Task Force will be reconvened to discuss progress on studies conducted with the guidance; and recommend changes to the guidance.
III.
PROBLEM IDENTIFICATION
Segment 3b of the San Miguel River is effected by sediment deposition from urban runoff. The decision to list Segment 3b on the 1998 303(d) List was based on nonattainment of the narrative sediment standard, specifically the impairment of aquatic life habitat and reproduction. During the period of late winter/early spring runoff, high siltation from urban street runoff and low flow in the San Miguel River causes a buildup of silt that covers the streambed in the stretch of River passing through Town. When the problem was first identified, it was suspected that sediment was filling the interstices of the gravel bed and likely smothering benthic macroinvertebrates and trout fry. Studies were conducted by the Telluride Institute (TI) to determine the sediment condition of the San Miguel, the contributing sources of sediment and possible solutions.
Sediment TMDL
Page 4
June 15, 2000
Colorado Water Quality Control Division
San Miguel River
Several studies consisted of the following: • Photographic essay of San Miguel River conditions • Mapping urban drainage to the San Miguel River • Measuring silt load from urban drainage waters and instream and • Assessment of sediment effects on benthic macroinvertebrates. The results of these studies indicated sediment impairment and the Division concurred with that determination and included Segment 3b on the 1998 303(d) List.
IV.
WATER QUALITY GOALS
The desired endpoint of this TMDL is the attainment of the narrative sediment standard for Segment 3b including the following goals: Goal No. 1:
30% reduction in sediment loading to Segment 3b of the San Miguel River
Goal No. 2:
95% reduction in sediment loading from Alder Street culvert of approximately 34 kilograms per day (kg/day) or 75 pounds (lbs/day)
Attainment of standards will be measured at seven sampling locations along Segment 3b (see Section VI. Technical Analysis). The goals apply specifically to the time of the greatest loads during the late winter/early spring runoff period. Reductions in loads are also expected during the other non-critical seasons.
V.
SOURCE ANALYSIS
The evaluation of sources contributing to the sediment loading in Segment 3b resulted to be nonpoint sources. The significant source of sediment and resulting impairment of aquatic life is high siltation due to urban runoff. The primary sources include (TI 1997A): 1) 2) 3)
Runoff originating above the Town of Telluride and being transported down Tomboy Road to the Town street grid Melt water originating from stored snow at the Town of Telluride maintenance facility at the west side of Town Runoff from the Town of Telluride street grid transported through the Alder Street culvert
Other tributaries in the Town of Telluride area contribute a small portion of the sediment load and are therefore considered a non-significant source. The principal source of the sediment is the runoff entering the river through the Alder Street culvert. During
Sediment TMDL
Page 5
June 15, 2000
Colorado Water Quality Control Division
San Miguel River
March of 1996, monitoring revealed suspended silt and clay. The drainage area collected through the Alder Street culvert consists of Tomboy Road and the sloping landscape north of town across Columbia Avenue to Alder Street. The point sources located along Segment 3b do not discharge significant amounts of sediment. In addition, they are located at the bottom of the segment downstream of the effected areas. The major loads of sediment were identified as originating from the three nonpoint sources mentioned above.
VI.
TECHNICAL ANALYSIS
A flow evaluation, source assessment and loading assessment were utilized to determine the maximum sediment load to Segment 3b to attain standards. Hydrology: This sediment TMDL is developed for the protection of aquatic life. Sediment may be transported during any storm event since Telluride streets are largely unpaved. Typically, summer thunderstorms have the greatest amount of energy and the highest potential for transporting silt from the Town streets. However, it has been observed that the late winter/early spring period has the greatest effect upon the River due to the following (TI 1997B): • • • • •
Runoff tends to have higher concentrations of silt particles per unit volume of water due to high automobile traffic associated with the ski season High insolation, as a consequence of high pressure weather, frequently follows snowstorms during the critical period and provides energy to melt snow Majority of Town is south-facing which induces rapid snowmelt Remaining watershed does not start to melt until after runoff from Town is complete and Flows of San Miguel River remain at winter low flows and are unable to transport silt through the river channel within Town.
The runoff associated with summer thunderstorms occurs simultaneously with high flows in the San Miguel River and sediment is therefore flushed through the system. The critical flow period for the loading of sediment is during the late winter/early spring runoff when the flows in the San Miguel are minimal. The acute (one day in three year interval, or 1E3) and chronic (30 day average in three year interval, or 30E3) low flows calculated for the San Miguel River from the United States Geological Survey (USGS) Station No. 09171200 (period of record from 1960 to 1965) are presented below in Table 2. Table 2 Low Flows for San Miguel River (cfs) Annual
Sediment TMDL
Jan
Feb
Mar
Apr
May
Jun
Page 6
Jul
Aug
Sep
Oct
Nov
Dec
June 15, 2000
Colorado Water Quality Control Division
San Miguel River
1E3
12
14
14
12
15
24
54
31
28
23
20
17
14
30E3
14
14
14
14
15
24
54
38
29
23
20
17
14
Source Assessment: The principal sediment load to Segment 3b was determined to be from nonpoint sources. This includes the runoff load from the unpaved streets in the Telluride area which enters the San Miguel River through the Alder Street culvert. In addition, significant stormwater drainage occurs to Alder Street via Tomboy Road which lies above Town. The silt load from the Alder Street culvert has been estimated as 80% of the total load to the River and therefore is the greatest nonpoint source contributor (TI 1997B). Background sources of Natural Background Source Contribution: sediment include the natural contributions from undisturbed land. Tributaries entering the San Miguel River contribute minor sources of sediment during the high flow conditions when compared with the contributions from the Alder Street culvert. The 1995 and 1996 studies were conducted to Loading Assessment: determine silt loads discharged to the River and instream silt loads. Silt Loading to River: During the 1995 studies, the entire river corridor through the Town of Telluride was evaluated for discharge points to the River. The results of the evaluation indicated that silt loads were far greater from the east side of Town due to geomorphology. The primary source of siltation due to runoff was determined to be the Alder Street culvert which drains the east portion of Town (See Figure 2). The maximum discharge from the Alder Street culvert occurred in early March of 1996 and delivered approximately 1 kg/min (2.2 lbs/min) of silt at a flow of 400 liters per minute (L/min) or 0.23 cfs. A sample of the discharge was taken and allowed to settle in still water. The settling rates were as follows: 60% settled in 20 minutes, 75% in 30 minutes and 80% in 45 minutes. An estimate of silt load to the River from the Alder Street culvert during the late winter/early spring period was then extrapolated to 36 kg (79 lbs). The silt load to the River from the remaining drainage locations was estimated at 12 kg/day (26 lbs/day). The total silt load to the River was then estimated at 48 kg/day (105 lbs/day) (TI 1997B). Loading estimates from the 1996 study were based in part on the following: • 58 day period of late winter/early spring runoff cycle (January 30 to March 29) • 2 grams per second (g/s) mean sediment discharge rate calculated by mean for 12 data points of 3 g/s and adjusted for days without runoff due to cold weather (1/3 of total days) • 5 hours per day runoff period Instream Silt Load: The instream silt load was measured at seven locations along the River including: 1) Bear Creek, 2) San Miguel above confluence with Bear
Sediment TMDL
Page 7
June 15, 2000
Colorado Water Quality Control Division
San Miguel River
Creek, 3) San Miguel below confluence with Bear Creek, 4) Fir Street bridge, 5) Mahoney Drive bridge, 6) Boomerang Road and 7) San Miguel at Society Turn (See Figure 3). Silt bedload samplers were installed along straight riffle stretches and later removed for analysis. The results of the instream analysis indicated high relative sediment loads below the Alder Street culvert. Biological study: Benthic macroinvertebrate sampling was conducted at each of the seven instream silt monitoring locations to compare conditions. Samples of benthic macroinvertebrates were collected with kick nets above the location of the silt bedload samplers before and after the 1996 winter runoff season. Limited data from census sampling indicated all aquatic insects were present with the exception of leaches and amphipods. Higher numbers of individuals were found above the Alder Street culvert than below. There are many factors which effect aquatic populations and therefore these results were only one aspect of the assessment of silt loading. Photographic essay: The photographic essay indicated observations of sediment impacts to the San Miguel River below the Alder Street culvert. These photographs were used as an additional indicator of sediment loading throughout the river corridor. Evaluation of Impairment and Required Reductions: As a result of the studies conducted by the TI, stream impairment of the San Miguel River through Town was assessed at the seven sampling locations. The degree of impairment was assessed in order to determine the required reductions in loads. As a result of the assessment, it was determined that only a portion of the segment was impaired and not the entire segment as originally thought. The San Miguel above the confluence with Bear Creek (Station 2) was chosen as the reference stream. The habitat and biological quality of each of the sampling locations was then compared to that of Station 2. The habitat quality was assessed by silt loading. The biological quality was assessed by the number of families of insects, number of insects and pollution tolerance index for insects. The results of this assessment are provided in Table 3. Table 3 Biological and Habitat Assessment of San Miguel River 2 3 4 5 6
Station
1
7
Sources Habitat
Background FS
Background N/A
Background FS
Urban runoff NS
Urban runoff PS
Downstream PS
Downstream PS
Biology
FS
N/A
FS
PS
PS
PS
FS
Station 2 was chosen as the reference condition and therefore the quality assessment is not applicable (N/A). Stations 1 and 3 were found to be fully supporting
Sediment TMDL
Page 8
June 15, 2000
Colorado Water Quality Control Division
San Miguel River
(FS) the habitat and biological quality of the reference stream. Station 4, below the Alder Street culvert, was not supporting (NS) the habitat quality and partially supporting (PS) the biological quality. Stations 5, 6 and 7 were either partially supporting or fully supporting both the habitat and biological quality. For this analysis, the habitat quality is used as the stronger indicator. The biological quality is dependent on a variety of conditions and therefore is considered as a lesser factor. The not supporting and partially supporting results are attributed to the silt loading from the Alder Street culvert. Reductions in loads from the culvert would improve the aquatic life habitat at Station 4 and downstream at Stations 5, 6 and 7. The loading from the Alder Street culvert is estimated at 80% of the total load to Segment 3b (TI 1997B). Reducing the Alder Street culvert load by 95% would improve the habitat at Stations 4 through 7 and bring Segment 3b into attainment of the narrative sediment standard. In terms of sediment loads, the current Alder Street load is 36 kg/day (79 lbs/day) (TI 1997B). A reduction of 95% of the current load is 34 kg/day (75 lbs/day). The anticipated reduced load from the Alder Street culvert is 2 kg/day (4.4 lbs/day). The existing total load to Segment 3b is estimated at 48 kg/day (105 lbs/day) (TI 1997B). Reduced loading from the Alder Street culvert of 34 kg/day (75 lbs/day) would result in a 30% reduction in total silt loading to the River. The anticipated reduced total load to Segment 3b is 14 kg/day (31 lbs/day). The remaining loads to the River would not require reductions in order to meet the underlying goals of improved aquatic life habitat. The remaining nonpoint source and background loads to the River would stay the same consisting of a total of 12 kg/day (26 lbs/day) sediment. Margin of Safety: The MOS for this TMDL is implicit. The TMDL reductions are allocated to the loads from the Alder Street culvert. Additional projects planned for implementation will further reduce sediment loads to Segment 3b. These additional anticipated reductions have not been quantified but will provide a MOS beyond the TMDL required for Segment 3b. In addition, monitoring should be conducted to verify that implementation of the management practices has reduced sediment loads in the River.
VII.
TMDL ALLOCATION
Allocation Methodology: The critical period TMDL for the stream is based on a LA of 2 kg/day (4.4 lbs/day) total sediment from the Alder Street culvert and a LA of 12 kg/day (26 lbs/day) total sediment from the other nonpoint and background sources and an implicit MOS. There is no WLA. The annual TMDL is equal to the sum of the LA and WLA. The annual TMDL for the River is 14 kg/day (31 lbs/day) total sediment.
Sediment TMDL
Page 9
June 15, 2000
Colorado Water Quality Control Division
San Miguel River
The TMDL will be implemented in the form of Best Implementation: Management Practices (BMPs) utilized along the stream corridor of Segment 3b. These Town of Telluride projects consist of the following: Stormwater Retention System and Constructed Wetland near Alder Street: A stormwater retention system will be installed which will induce sedimentation of entrained particles. In addition, a wetland has been constructed adjacent to the river near Alder Street and is designed to filter runoff from the Town streets before reaching the San Miguel River. The design is estimated to remove 95% of the sediment discharged from the Alder Street culvert during the critical winter period. Lesser amounts of sediment will also be removed during high volume rain events. Snow Storage Facility: Minor sediment loads will be reduced by managing snowmelt from the Town of Telluride snow storage facility located on the west side of Town (upstream of Station 6). Snowmelt will be directed through a series of managed wetlands to filter the water prior to entering the San Miguel River. Significant loads of sediment are transported during storm Tomboy Road: events down Tomboy Road. Solutions for managing Tomboy Road runoff were identified and will result in diverting runoff across well-vegetated slopes and through storm drains. The runoff from Tomboy Road which enters the Alder Street culvert will further be reduced by the Alder Street retention system and constructed wetland. Town of Telluride River Restoration: The Town of Telluride will restore a 0.7 mile stretch of the river from below the confluence with Bear Creek to Fir Street, adjacent from the Town Park (in vicinity of Station 4). The goals of the river restoration project are to restore aquatic, wetland and riparian habitat; improve river hydraulics; and balance sediment movement throughout the channel. Improvements will be made to the river channel and river bank, as well as existing wetland and riparian areas. A public stakeholders group developed the concept plan with assistance from an environmental consultant and funding from the United States Environmental Protection Agency (EPA) and Town of Telluride. The project is funded by a five hundred thousand dollar grant from the Natural Resource Damage fund. Post Implementation Monitoring: Monitoring of the instream silt load is required to determine if the reductions are being achieved. A control point established on the San Miguel River just above the confluence with Bear Creek (Station 2) should be used for comparisons. Sediment load reductions should be monitored at the point just above the Fir Street Bridge (Station 4). Silt bedload samplers should be installed across the streambed at the monitoring and control point and located in a straight riffle area. The samplers should be measured after the critical runoff period and compared to results from the control point and sampling point during the 1996 study as follows: Station 2 silt load of 0.40 g/dm2 and Station 4 of 29.3 g/dm2. Additional sampling is necessary at the downstream locations (Stations 5, 6 and 7) to determine attainment of the sediment standard throughout Segment 3b.
Sediment TMDL
Page 10
June 15, 2000
Colorado Water Quality Control Division
San Miguel River
Silt load should also be measured at the Alder Street culvert to determine the effectiveness of the installed BMPs. Monitoring loads from the Alder Street culvert should be conducted during the same time period as the silt bedload sampling. Runoff rates and river flows should then be compared with those measured during the 1996 study. Monitoring should be conducted during the late winter/early spring runoff period for a two-year cycle.
VIII. PUBLIC INVOLVEMENT This TMDL has been studied and developed over the years by local residents including the Telluride Institute and the San Miguel Watershed Coalition. In addition, the compilation of the Colorado 1998 303(d) List was a public process. The public notice period for this TMDL during the month of May 2000 yielded no comments. The local sponsor of the San Miguel River restoration efforts is the Town of Telluride. Many other organizations and agencies have contributed to the planning process including: representatives from the San Miguel Watershed Coalition, Adhered Mining Company, Colorado Department of Public Health and Environment, San Miguel Valley Corporation, Colorado Department of Wildlife, San Miguel County Health Department, Adhered Reason Committee, Sheep Mountain Alliance, Trout Unlimited, San Miguel Conservation Foundation, Regional Trails Council, Telluride Open Space and Parks and Recreation Department. In addition, information on the River Corridor and Wetland Restoration Plan has been disseminated through libraries and schools in the area.
Sediment TMDL
Page 11
June 15, 2000
Colorado Water Quality Control Division
IX.
San Miguel River
REFERENCES
WQCC 1998A: Colorado Department of Public Health and Environment, Water Quality Control Commission, 1998 303(d) List of Impaired Waters, 1998. WQCC 1998B: Colorado Department of Public Health and Environment, Water Quality Control Commission, WQCC Policy 98-1, Provisional Implementation Guidance for Determining Sediment Deposition Impacts to Aquatic Life in Streams and Rivers, 1998. WQCC 1999A: Colorado Department of Public Health and Environment, Water Quality Control Commission, Classifications and Numeric Standards for Gunnison and Lower Dolores River Basins, Regulation No. 35, Amended January 30, 1999. WQCC 1999B: Colorado Department of Public Health and Environment, Water Quality Control Commission, The Basic Standards for Methodologies for Surface Water, Regulation No. 31, 5 CCR 1002-31, Amended March 3, 1999. TI 1996: Telluride Institute Inc., San Miguel River Through Telluride, Colorado, January 15, 1996. TI 1997A: Telluride Institute Inc., Summary Report: Town of Telluride Runoff Studies, September 27, 1997. TI 1997B: Telluride Institute Inc., An Assessment of Siltation and its Effects Upon the San Miguel River from Unpaved Streets in Telluride, Colorado, September 27, 1997. TI 1998: Telluride Institute Inc., A Total Mean Daily Load for Silt from Telluride’s Unpaved Streets Before and After Proposed Mitigation, March 23, 1998.
Sediment TMDL
Page 12
June 15, 2000
Colorado Water Quality Control Division
Sediment TMDL
San Miguel River
Page 13
June 15, 2000
Colorado Water Quality Control Division
Sediment TMDL
San Miguel River
Page 14
June 15, 2000
Colorado Water Quality Control Division
Sediment TMDL
San Miguel River
Page 15
June 15, 2000
Colorado Water Quality Control Division
San Miguel River
Appendix A Parameter
Table Value Standard (ug/L unless noted)
Ammonia
acute =0.43/FT/FPH/2 (4) (mg/L) chronic = 0.02 (mg/L)
Cadmium
acute (trout) =e (1.128[ln(hardness)]-3.828) chronic = e (0.7852[ln(hardness)]-3.490)
Chromium III
acute =e (0.819[ln(hardness)]+3.688) chronic =e (0.819[ln(hardness)]+1.561)
Chromium VI
acute =16 chronic =11
Copper
acute =e (0.9422[ln(hardness)]-1.4634) chronic =e (0.8545[ln(hardness)]-1.465)
Lead
acute = e (1.6148[ln(hardness)]-2.8736) chronic =e (1.417[ln(hardness)]-5.167)
Nickel
acute =e (0.76[ln(hardness)]+4.02) chronic =e (0.76[ln(hardness)]+1.06)
Selenium
acute =20 chronic =5
Silver
acute = e (1.72[ln(hardness)]-7.21) chronic (trout) =e (1.72[ln(hardness)]-10.51)
These hardness based metals equations are calculated using ambient hardness values. Typically, as hardness decreases, toxicity increases. For more information on Colorado=s water quality standards please refer to Basic Standards and Methodologies for Surface Waters, Regulation No. 31 (WQCC 1999B).
Sediment TMDL
Page 16
June 15, 2000
