UNITED STATES ENVIRONMENTAL PROTECTfON AGENCY REGION 8 999 18"' STREET - SUITE 380 DENVER, CO 80202-2466 http:Ihww.epra.govlregionO8

RECElVED SEP 0 5 2000

I

J: David Holm, Director water QuaIity Control Division Colorado Department of Public Health and ~nvironmknt 4300 Cherry Creek Dr.S. Denver, Colorado 80246- 1530

I

Re:

TMDL Approvals pox Canyon Creek (sediment)

Dear Mr. Holm:

We have completed our review of the total by ydur office hr the waterbodies listed in the cled ~ a t e r ~ c t ( 3 3 U . S . 1251 C. et for water quality limited

daily loads (TMDLs) as submitted letter. In accordance with the

de

d

I Based on our review, we feel the separate L elements listed in the enclosed review table adequately address the pollutants of concern, k g into consideration seasonal variation and a margin of safety. Please find enclosed a detailed review of these TMDLs. Thank you for your submittal. If you have a n j questions concerning this approval, feel free tb contact Kathryn Hernandez ofmy staffat 3031 12-6101.

9

Max H. Dodson Assistant Regional Administrator Office of ~ c o s ~ { t e m Protection s and Remediation

Enclosure

@Printed

on m

d Paps

I

TOTAL MAXIMUM DAILY LOAD ASSESSMENT BOX CANYON CREEK MONTEZUMA COUNTY, COLORADO June, 2000

TMDL SUMMARY Waterbody Name/Segment Number

Mancos River and tributaries above Highway 160/COSJLP04

Pollutant/Condition Addressed

Sediment

Affected Portion of Segment

Box Canyon Creek

Use Classification/Waterbody Designation

aquatic life cold I, recreation I, water supply, agriculture Reviewable

Waterbody Designation Water Quality Target

< 25% fines (<8mm) at all instream assessment sites; road density of 1.8 mi/mi2 throughout watershed

TMDL Goal

macroinvertebrate community diversity (EPT:C . 0.5) restored throughout Box Canyon Creek

I.

EXECUTIVE SUMMARY Box Canyon Creek is a tributary to the West Mancos River and lies entirely within the San Juan National Forest in Montezuma County, Colorado. Box Canyon Creek was included on the 1998 Colorado 303(d) list because excessive sediment deposition had resulted in the stream not supporting its cold water class I aquatic life use designation. The road system developed to support timber harvest, grazing and recreational access represents the most significant source of sediment loading to the stream. The United States Forest Service has initiated transportation management planning for the forest which involves closure and/or rehabilitation of of approximately 31 miles of the 35 miles of roads within the Box Canyon Creek watershed. Installation of drift fencing to restrict cattle movement within the forest and additional restrictions on grazing within the watershed are also anticipated. These measures are expected to reduce sediment loading, thereby reducing accumulation of fine diameter particulates in the more severely impacted reaches of Box Canyon Creek. The change in streambed particle size distribution is, in turn, expected to improve invertebrate community structure in the impaired reaches of stream.

II.

INTRODUCTION 1

Section 303(d) of the federal Clean Water Act requires states to identify water bodies or stream segments which are water quality limited. Those water quality limited segments currently identified in Colorado are identified in 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 (ATMDL@). The TMDL is comprised of the Load Allocation (ALA@) which is that portion of the pollutant load attributed to natural background or the nonpoint sources, the Waste Load Allocation (AWLA@) which is that portion of the pollutant load associated with point source discharges, and a Margin of Safety (AMOS@). 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. Box Canyon Creek does not support its present designated aquatic life use (cold, class 1) due to excessive sediment deposition. It was therefore included on Colorado=s 1998 303(d) list. Box Canyon Creek was not Atargeted@, or designated as a high priority waterbody for purposes of TMDL completion. However, the United States Forest Service (AUSFS@) has completed assessment of the drainage and has prepared a watershed restoration plan for Box Canyon Creek. Development of this TMDL is therefore timely and appropriate. The Box Canyon Creek watershed is fairly small, totaling some 3,200 acres (or 5 square miles). The watershed lies entirely within the boundaries of the San Juan National Forest, in Montezuma County, Colorado (Figure 1). The San Juan National Forest is managed so as to provide livestock grazing, timber harvest, and recreation opportunities. Box Canyon Creek is approximately three miles in length from its headwaters to its confluence with the West Mancos River. The Box Canyon Creek watershed lies within the area designated by the United States Geologic Survey as hydrologic unit code 14080107. A map of the Box Canyon Creek watershed is attached as Figure 1. The USFS has prepared an Environmental Assessment (AEA@) which addresses a proposed timber sale as well as restoration activities within the Box Canyon Creek watershed. The timber sale, as described in the EA, was expected to go to bid in 2000 with harvesting commencing in 2000 or 2001. Public notice of the EA generated a volume of comments concerning the proposed timber sale. It is, at this point, uncertain whether the sale will occur. Should the sale proceed, timber harvest would be expected to take place over a three to four year period. The EA identifies specific conditions intended to mitigate potential impacts to the watershed should the timber sale proceed.

The EA also addresses modifications to the forest transportation plan within the 2

watershed. The transportation plan modifications include closure and/or rehabilitation of some roads prior to the timber sale and additional closures which will coincide with and follow timber harvesting. Should the timber sale not proceed, road closure and rehabilitation activities will be unchanged, but will likely follow an accelerated schedule. The watershed restoration activities identified in the EA are expected to proceed under a USFS decision issued independent of the timber sale decision. USFS land use management is also implemented through the use of Allotment Management Plans (AAMPs@). AMPs are executed between the USFS and permittees who hold grazing rights within the forest boundaries. The USFS periodically reopens the AMPs for the purpose of incorporating appropriate range management requirements. Such requirements are developed so as to reflect and respond to current and target range/pasture conditions. The AMPs within the Box Canyon Creek watershed will be reopened in 2004.

III.

WATER QUALITY STANDARDS The applicable water quality standards for Box Canyon Creek are those assigned to segment 04 of the La Plata River Sub-Basin of the San Juan River Basin. Segment 04 includes all tributaries to the San Juan River which are within the Weminuche Wilderness Area and the South San Juan Wilderness Area and is designated for the following uses: water supply, agriculture, recreation (1), and aquatic life (cold 1). Box Canyon Creek does not fully support the aquatic life designation due to accumulation of excessive amounts of sediment. Colorado water quality standards do not include a numeric criteria for parameters related to sediment accumulation. Instead the Colorado Basic Standards and Methodologies for Surface Waters (5 CCR 1002-31) includes a narrative standard which specifies that: AExcept 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 discharger in amounts, concentrations or combinations which...can settle to form bottom deposits detrimental to beneficial uses.@ Waters which are identified on the Colorado 303(d) list of impaired waters as impaired due to sediment are therefore identified as not attaining the assigned aquatic life classification due to the impacts of sediment deposition on fish and invertebrate reproduction and habitat. None of the aquatic species identified within the watershed are listed threatened or endangered species.

Segment 04 of the La Plata River Sub-Basin of the San Juan River Basin is designated as 3

a reviewable water in the Classifications and Numeric Standards for San Juan River and Dolores River Basins, Regulation 34 (5 CCR 1002-34). As such, Box Canyon Creek is subject to antidegradation review. Antidegradation requirements are established in The Basic Standards and Methodologies for Surface Water, Regulation 31 (5 CCR 1002-31). Section 31.8(3)(a) requires antidegradation review of Aregulated activities with new or increased water quality impacts that may degrade the quality of state surface waters that have not been designated as outstanding waters or use-protected waters...@. Regulated activities are defined to include Aany activities which require a discharge permit or water quality certification under federal or state law, or which are subject to state control regulations...@. The activities addressed in the USFS Environmental Assessment; Lucy Timber Sale and Box Canyon Watershed Restoration do not require a discharge permit, nor do they require water quality certification. Antidegradation review requirements are therefore not applicable to the TMDL.

IV.

PROBLEM IDENTIFICATION The USFS in 1996 completed Stream Health Survey evaluations at five locations on Box Canyon Creek. The survey results suggest that, for the purpose of this analysis, the stream be considered in four sections or reaches. Reach 1 lies furthest downstream and extends from the confluence with the West Mancos River to a point below the confluence with an un-named tributary originating at North Rampart Springs, a distance of approximately one half mile. Reach 2 extends some one and a half miles upstream to the confluence of Box Canyon Creek with an un-named tributary originating at State Reservoir. Reach 3 runs approximately one half mile to a point below road 331. Reach 4 then extends to the Box Canyon Creek headwaters. It is in reach 4 that Box Canyon Creek transitions from an intermittently to a perennially flowing stream. Stream reaches are shown in Figure 2. The USFS Stream Health surveys included determination of sediment particle size distribution, assessment of riparian vegetation cover and condition, evaluations of stream bank erosion potential, and invertebrate census data and observations of fish abundance. Vegetative assessment and erosion potential was evaluated based upon field observations of USFS hydrologists. Particle size determination was calculated via pebble count measurements. Surber samplers were used to collect invertebrate samples which were subsequently identified at the United States Bureau of Land Management Laboratory at Utah State University in Logan, Utah. All observations and sample collection occurred in 1996.

Physical and biological community characteristics of Box Canyon Creek are significantly 4

degraded as one proceeds from the confluence with the West Mancos River towards the upper reaches. The vegetative community is dominated by spruce/fir forest. Cottonwoods are found in the lower elevations, giving way to aspen as the elevation increases. Riparian vegetation in the lower reaches is comprised of willows in fair to good condition. Willows are absent from the streambank in the extreme lower end of reach 4, but re-appear as one moves upstream. Observations of streambank trampling by cattle in lower reach 4 suggest that willows might otherwise be present throughout the drainage. The streambank itself is unstable in all but the lowest and uppermost reaches. The streambed in the upper reaches is subject to significant accumulations of fine sediment (< 8mm). USFS field observations note particularly heavy sediment deposition in those areas proximate to roadways. Particle size distributions for the five sample locations are illustrated in Figure 4. The macroinvertebrate community in the lower reaches is diverse with ephemeroptera (mayflies), plecoptera (caddisflies), and tricoptera (stoneflies) together representing the predominant taxa. Chironomids (true flies) are the most abundant taxa present in the two uppermost reaches. Fish, including rainbow trout, are abundant above the confluence with the West Mancos River and, although less populous, continue to be found in reach 2. Fish are absent in reaches 3 and 4. However, because of the ephemeral nature of Box Canyon Creek above road 331, no fish would be expected in reach 4. Delivery of sediment to Box Canyon Creek is a sporadic event tied to precipitation events and periods of snowmelt. However, the land use activities which contribute sediment are not seasonal in nature. Although there may be a seasonal aspect to timber harvest, grazing and road development, the removal of vegetative cover, whether due to grazing, timber harvest, or road construction, is a cumulative process which has resulted in increased sediment load over a relatively long term.

V.

WATER QUALITY GOALS The composition of stream substrate is a function of sediment load and size, stream slope, and stream velocity. The substrate of mountain streams tends to be characterized by gravel to boulder sized rubble; smaller particles are washed downstream by the fast moving current. Plains streams, because of their shallow gradient and resultant lesser velocities, tend towards fine grained, sand and silt substrates. Within any flowing waterbody stream velocities vary in accord with the slope and geomorphology of the stream. Even in relatively steep mountain streams, flows in eddies and pools may be quite slow. Consequently the stream bottom in these areas may be predominantly fine grained particles. Excessive sediment loading to the stream will result in sand and silt substrates predominating even in rapidly flowing stretches.

The instream biological community is shaped by various environmental factors 5

influencing water quality and instream habitat. Composition of the stream substrate is an important determinant of biotic community structure and abundance. Cobble, gravel and stone substrates provide habitat for a diverse assemblage of benthic macroinvertebrates as well as eggs and early life stages of numerous fish species. The macroinvertebrate population represents a substantial portion of the diet available to various game and nongame fish species. Infilling of these interstitial spaces with fine particulates eliminates habitat for many invertebrate taxa, resulting in a benthic community dominated by those relatively few macroinvertebrate taxa adapted for such conditions. Fish eggs are buried and smothered. Shelter for early life stages of piscine species is likewise eliminated. Particle size distribution data developed by the USFS indicates that the streambed in reaches 3 and 4 is composed primarily of fine grained materials less than 8 millimeters in diameter. Substrate composition in the lower reaches of Box Canyon Creek is more typical of mountain streams. Fine grained materials compose some 20 percent of the streambed in reaches 1 and 2. Biological assessment of Box Canyon Creek indicates that the aquatic life cold/class 1 designation is attained in the lower reaches, suggesting that a reduction of the percentage of fine grained particles comprising the substrate in the upper reaches to a level similar to that measured in the lower reaches is an appropriate goal for determining success of TMDL implementation. A reduction in the relative percentage of particles of less than 8 mm to 25 percent in all reaches has therefore been identified as a water quality target for Box Canyon Creek. Benthic macroinvertebrates are important elements of water quality evaluations because they 1) live on, or near streambed sediments, 2) have relatively long life cycles, and 3) are relatively sessile organisms. These characteristics result in a macroinvertebrate community which reflects the natural and anthropogenic factors affecting instream water quality and habitat. Benthic macroinvertebrates are therefore well suited for use in assessing site-specific water quality and comparing spacial patterns of water quality at multiple sites. The distribution of benthic macroinvertebrates in a stream reflects natural and anthropogenic conditions. Macroinvertebrate community structure can therefore be utilized as an indicator and delineator of water quality degradation as well as providing measurable targets for evaluation of watershed restoration activities.

Specific taxonomic groups of macroinvertebrates exhibit a relatively greater degree of 6

sensitivity to pollution than others. Macroinvertebrates belonging to the Orders Ephemeroptera, Plecoptera and Tricoptera are generally considered to be relatively intolerant of high sediment loading, toxics (such as heavy metals), and nutrient enrichment. Conversely, macroinvertebrates classified in the Chironomidae are relatively unaffected by typical pollutants, including sediment. Such taxa may thrive in degraded instream conditions. Diversity of the macroinvertebrate community, referred to as richness, may be characterized at several taxonomic levels. Taxonomic richness generally decreases with decreasing water quality. Indexes of Ephemeropteran/Plecopteran/Tricopteran (EPT) richness and comparisons of the abundance of these taxa in comparison to chironomid abundance (EPT:C ratio) are useful indicators of water quality based upon community diversity. The abundance of macroinvertebrates per unit area is an indicator of habitat availability (density) and food abundance. However, chironomid abundance in a degraded system, one perhaps impaired as a result of excessive nutrient or sediment loading, may more than offset the reductions in EPT abundance. Therefore, this measure may be inappropriate in certain situations. The benthic community in Box Canyon Creek exhibits reduced EPT richness, as well as overall taxonomic richness, in those reaches characterized by increased sediment deposition (Table 1). EPT:C ratios indicate that chironomid taxa tend to predominate the benthic community in those reaches. Reduced sediment loading in the upper reaches is expected to be reflected an increased presence of EPT taxa. Therefore, a water quality target established in this TMDL will be the attainment of EPT:C ratios in the upper reaches of Box Canyon Creek which approach those observed downstream. Attainment of an EPT:C ratio of 0.5 or greater will be applied at each monitoring location in reaches 3 and 4 as an indicator of successful TMDL implementation.

Table 1. Box Canyon Creek Macroinvertebrate Population Indices

VI.

sample site

stream reach

total richness

EPT richness

EPT:C ratio

1

1

34

14

0.614

2

1

37

20

0.678

3

2

30

15

0.783

4

3

23

7

0.134

5

4

25

10

0.377

SOURCE ANALYSIS

7

The results of sampling performed by the USFS has been summarized in section IV. PROBLEM IDENTIFICATION. Roadways constructed to support timber harvest, livestock grazing, and recreation within the watershed are the primary source of sediment. Sediment impacts, as evidenced by the physical composition of the stream substrate and the make-up of the benthic community, are most apparent in the upper reaches of the watershed, areas where road density is greatest and many roadways are situated in proximity to the stream. Exacerbating the problem is additional sediment loading resulting from trampling of riparian vegetation and degraded pasture in the uplands. Land uses within the watershed are divided into three categories by the USFS. These include Asemi-primitive recreation@, Alivestock grazing@, and Awood fiber production@. Historic land uses within the watershed are illustrated in Figures 5 and 6. The USFS has developed Forest Plan Standards and Guidelines which identify road density standards for various land uses. Over 80 percent of the 3,223 acres within the Box Canyon Creek watershed are managed for livestock grazing. The Forest Plan Standards and Guidelines (FPS&G) specified road density for grazing use is 0.5 to 1 linear mile of roadway per square mile (mi/mi2). The portion of the watershed managed for wood fiber production is considerably less, some 164 acres. The current road system in these areas also exceeds the FPS&G density criteria of 1 to 3 mi/mi2. There are no road density standards for the 450 acres classified as semi-primitive recreation, and, in fact, the road density is substantially less in this management area than in the other two. The current road density throughout the Box Canyon Creek watershed is estimated to be 6.9 mi/mi2. Most of the transportation network is located within areas managed for grazing, however, it should be noted that the roads located in these areas also support timber harvest and recreational activities. The West Mancos grazing allotment, of which the Box Canyon Creek watershed is a part, has been grazed at approximately the same level (defined by USFS as animal unit months) since the 1950's. The most recent range analysis of the West Mancos allotment was performed in 1983. At that time 83 percent of the allotment was classified as fair or good range condition. The parks and meadows within the allotment are subject to more intense grazing pressure than other vegetative communities (aspen, oak, and spruce/fir forests) in the grazing allotment. In 1983 the vegetative condition in the parks had deteriorated to less than five percent desirable plant species (desirable plant species being defined as such based upon their forage value). The vegetative community was dominated by Kentucky Bluegrass (in 1983 defined as having an intermediate value as livestock forage) and other species considered to be undesirable as livestock forage. The USFS currently assesses vegetative condition based upon the site=s species composition in comparison to a reference condition representing optimal community diversity and production. Application of current standards to the 1983 range analysis data would result in a finding that range conditions are, at present, unsatisfactory.

Trampling of riparian vegetation by livestock has been documented in USFS stream health surveys. Surveys performed in 1996 noted particularly severe problems in reach 4. 8

The particle size distribution in reach 4 exhibits the highest percentage of fine particles. Timber blowdown below reach 4 limits livestock movement below that point until reach 1 where animals move upstream from the Mancos River bottom. Trampling in reach 1 does not, however, approach the severity of that found in reach 4. Forested areas within the Box Canyon Creek watershed are dominated by aspen with smaller areas of oak and spruce/fir. Aspen stands comprise some 1469 acres or 46 percent of the watershed and have been harvested since the 1950's. Some 575 acres are considered to be Aharvestable@ using current USFS criteria. The EA considers five alternatives, including a no action alternative, opening different areas for aspen harvest. Timber harvest contributes sediment load to Box Canyon Creek via surface runoff from roads and skid trails constructed to facilitate this activity. Debris deposited in wetlands, grasslands and riparian areas adjacent to the harvest area may also damage the vegetative cover, resulting in increased sediment load.

VII.

TECHNICAL ANALYSIS Sediment loading to Box Canyon Creek is tied to land use within the Box Canyon Creek watershed. Roadways in and of themselves are significant sediment sources. Destruction of riparian vegetation, grazing and timber harvest further reduce vegetative cover in upland areas. Sediment delivery is accomplished by surface runoff transporting sediment from areas of diminished vegetation during precipitation events and periods of snowmelt. Roads in the watershed direct runoff along pathways which lack vegetation, minimizing any attenuation of the sediment load which would occur in a natural drainageway. Although there are seasonal aspects to these land use activities, and to the hydrologic events which introduce (and ultimately remove) sediment into Box Canyon Creek, it is the cumulative result of various activities impacting the riparian and upland vegetative community which both generates the sediment load and minimizes any potential reduction in sediment load arising from the filtering effect of vegetation proximate to the stream. These cumulative impacts are not seasonal in nature.

The San Juan Forest Plan articulates watershed restoration goals in terms of attainment of assigned state water quality standards. The Environmental Assessment for the Lucy 9

Timber Sale and Box Canyon Watershed Restoration therefore considers those water quality standards (and identifies mandatory requirements or restrictions which are applicable to timber harvest activities) in its evaluation of timber sale alternatives. Each timber sale alternative, save the no action alternative, incorporates conditions which address sediment loading resulting from timber harvest and associated roadways. The EA also addresses sediment loading associated with those additional roadways not constructed and maintained to support timber harvest activities, and sediment loading resulting from livestock grazing. Because all potential sediment sources are addressed in each alternative, it is not necessary to quantify sediment loading from individual sources or activities, nor is it necessary to allot a specific load to each source or activity.

VIII. TOTAL MAXIMUM DAILY LOAD Sediment loading to Box Canyon Creek will be reduced through a series of actions directed at modifying the significant land uses within the watershed. These measures are identified in the USFS Environmental Assessment, Lucy Timber Sale and Box Canyon Watershed Restoration. The USFS proposes implementation of these measures regardless of the timber sale alternative which is ultimately selected. The most significant action is a series of modifications to the road system within the Box Canyon Creek drainage. There are, at present, an estimated 34.7 linear miles of roadway within the watershed (10.8 miles of which have been closed but for which no additional rehabilitation has been accomplished). These roads have been constructed in such a way that they contribute a substantial portion of the sediment load to Box Canyon Creek. The watershed restoration plan developed by the USFS (and incorporated into the EA) anticipates the closure of some 25.6 miles of roads (see Figure 7). Closure may involve recontouring of the roadway and any stream crossings to approximate their original conditions, construction of waterbars or other sediment control structures, and revegetation of disturbed areas. Some 9 miles of roads will remain in place, 4.1 miles of which will be rehabilitated so as to improve cross drainage. Road density within the watershed will consequently be reduced from the current level of 6.9 mi/mi2 to 1.8 mi./mi2. The implementation of these measures will reduce road density within the watershed to a level which meets the USFS guidelines for the forest uses. With the additional rehabilitation of 4.1 miles of the remaining roads, a substantial reduction of sediment loading within the watershed is expected. Any additional roads constructed to facilitate timber harvest will be constructed so as to minimize sediment transport and are to be closed and rehabilitated upon the cessation of timber harvest.

Conditions attached to any timber sale, should an option other that the no action alternative be selected, will require operations be conducted in such a way as to minimize 10

the potential that such operations result in additional sediment loading to the stream. These operational practices include: 1) requirements that residual timber remain in the cutting unit so as to provide soil cover, 2) a prohibition on activities such as skidding, loading and decking in wetlands, riparian areas and upland grasslands, 3) restrictions on timber harvest on steeply (35 percent or greater) sloped areas, 4) restrictions on timber harvest during spring snowmelt, heavy rains, or other periods when soil moisture is such that soil damage may occur, and 5) siting and design requirements for landings and skid trails intended to contain and/or minimize runoff and associated sediment transport. Selection of a timber sale alternative other than the null alternative will likely delay attainment of the TMDL goal due to short term sediment loading associated with timber harvest. However, road system closure and rehabilitation will proceed in parallel with any timber sale. Any increase in sediment loading from timber harvest activities is expected to be offset by sediment load reductions resulting from road system remediation. Therefore, even should the proposed timber sale proceed, no net increase in sediment delivery to Box Canyon Creek is expected. Allotment Management Plans will be reopened and appropriate requirements will be incorporated to reduce sediment transport associated with livestock grazing. Requirements may include reductions in animal density, reductions in the period during which animals are allowed to graze a particular parcel, use of salt blocks and watering stations to direct animals away from the stream. These measures are expected to facilitate re-establishment of willows along reach 4 where trampling of riparian vegetation has been particularly extensive. Drift fencing will be installed along the lower reaches of Box Canyon Creek. The drift fencing is intended to restrict the movement of cattle along the streambed and thereby reduce or eliminate destruction of riparian vegetation along reach 1. Further reduction of sediment loading in the lower stream reach will result. The measures described are intended to reduce sediment loading to the Box Canyon Creek such that the sediment accumulation throughout the system is comparable to the lower reaches. A target particle size distribution approximating that currently found in the lower reaches has been selected. The target particle size distribution identifies a reduction in the relative percentage of particles of less than 8 mm to 25 percent or less. USFS pebble counts indicate that the substrate in reach 3 is composed of about 70 percent fines; almost 50 percent in reach 4.

Attainment of the target particle size distribution is expected to result in restoration of a macroinvertebrate community structure which is currently evident in only the lowermost 11

reaches. Benthic community structure will be assessed via measurement of the EPT:C ratio. A target EPT:C ratio of 0.5 has been selected. The macroinvertebrate population in the lower reaches is believed to be representative of that which would be expected in the upper reaches upon restoration of the benthic habitat. The USFS anticipates implementation of the watershed remediation actions incorporated into the Environmental Assessment, Lucy Timber Sale and Box Canyon Watershed Restoration regardless of the timber sale alternative which is ultimately selected. Because the watershed remediation plan will address all sediment sources, there is no need to allocate sediment loads to the various categories of sediment sources. Post implementation monitoring will be performed by USFS and WQCD personnel for a period of three years after restoration activities are completed. Monitoring will include the physical and biological assessment procedures which were initiated in 1996, however, annual monitoring may not include all physical and biological assessments at each monitoring location. Comprehensive monitoring will be performed for the third year after remediation is completed. The TMDL must incorporate a Margin of Safety to account for any uncertainty related to data quality and efficacy of control measures. The Box Canyon Creek TMDL incorporates several elements which provide the requisite Margin of Safety. The TMDL addresses all potential sediment sources and identifies mitigation for each. There is no allocation of sediment loads among sources, the TMDL instead will result in implementation of measures aimed at minimizing or eliminating all possible sediment sources. The TMDL also incorporates physical and biological endpoints. Through use of multiple endpoints, there is greater assurance that achievement of the identified water quality targets will indeed result in attainment of the assigned class 1 cold water aquatic life classification. Post-implementation monitoring will provide documentation of the efficacy of the control mechanisms and ultimate attainment of the designated aquatic life use. IX.

PUBLIC INVOLVEMENT Box Canyon Creek was included on the 1998 303(d) list of impaired waters in Colorado based upon stream health assessments and water quality data developed by the USFS. 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.

Development of the TMDL is based heavily upon information provided by the USFS in the Environmental Assessment; Lucy Timber Sale and Box Canyon Watershed 12

Restoration. The USFS has reviewed draft materials and provided additional comment to the WQCD during the TMDL process. The Environmental Assessment; Lucy Timber Sale and Box Canyon Watershed Restoration is subject to a public review process. A 30 day public comment period closed on October 22, 1999. The USFS on April 13, 2000 approved the Lucy Timber Sale, with will involve the harvest of some 2.0 million board feet of aspen on 168 acres of Forest Service lands. The TMDL itself is subject of an independent public process. The WQCD convened a public meeting to discuss the preliminary Box Canyon Creek TMDL, and several other draft TMDLs, on January 25, 2000. Sierra Club provided a copy of comments to the USFS concerning the draft EA at that time. No comments directly concerning the TMDL were submitted at that time. The TMDL was made available for additional review and comment during a 30 day public notice period in May, 2000. Notice was provided in the Colorado Water Quality Bulletin, the Colorado Statesman, and via the Division=s TMDL webpage. Comments regarding the TMDL were received from the Region VIII office of EPA and from EarthJustice (AEJ@). EPA had been provided a draft of the TMDL prior to public notice. Changes to the TMDL resulting from EPA comments were incorporated into the public noticed version of the TMDL. Comments from EJ were received during the public notice period. Both sets of comments are summarized below as are the Division=s responses. EPA had noted that the TMDL had not been scheduled for completion until 2001 or 2002 and suggested that a statement as to the rationale for the earlier completion be added. Box Canyon Creek was not Atargeted@, or designated as a high priority waterbody for purposes of TMDL completion when the 1998 section 303(d) list was prepared. However, the United States Forest Service had completed assessment of the drainage and had prepared a watershed restoration plan for Box Canyon Creek. Development of this TMDL is therefore timely and appropriate. A comment to this effect has been added to Section II., INTRODUCTION of the TMDL. EPA also inquired as to whether any of the affected aquatic life are endangered species. None of the fish or macroinvertebrate species identified in the watershed surveys are listed threatened or endangered species. This has been noted in Section III., WATER QUALITY STANDARDS.

EPA suggested the Water Quality Target section of the TMDL table (page 1) be amended to identify the desired EPT:C ratio. The goal of the TMDL is attainment of the narrative 13

aquatic life use designation. The Division believes that the EPT:C ratio, in this instance, represents an appropriate indicator of that goal. The TMDL table was therefore amended to specify the EPT:C ratio, but in the context of the TMDL goal rather than as a water quality target. EJ provided several related comments. First, EJ noted that the road density standard seems to be a method of TMDL implementation, rather than a water quality goal or a measure of sediment loading. The Division agrees that the road density standard is first and foremost a measure of TMDL implementation. Because roadways in the drainage are the most significant sediment source, however, road density may also be utilized as a surrogate for more direct water quality indicators. Identification of multiple water quality targets is desirable in that the ultimate attainment of multiple targets would suggest a greater likelihood of achieving the TMDL goal. In fact, identification of multiple endpoints, direct and indirect, represents a component of the TMDL margin of safety. The Division believes inclusion of a road density based target is an appropriate element of the TMDL. EJ also commented relative to selection of an EPT:C ration of 0.50 as the TMDL goal since the EPT:C ration in the lower reaches of the watershed range from 0.614 to 0.783. The lower ratio was selected because streamflows in the upper reaches of the Box Canyon Creek watershed are intermittent in nature. It is therefore not reasonable to expect a EPT:C ration which approaches that documented for the lower reaches where there is continuous instream flow. Conversely, this suggests that the lower reaches represent less than optimal reference conditions. This is true to some extent, however, extensive surveys within the Box Canyon Creek drainage, and surrounding watersheds, failed to yield better candidate reference segments. Nonetheless language has been added to Section V., WATER QUALITY GOALS, and VIII., TOTAL MAXIMUM DAILY LOAD, to clarify that the TMDL goal of 0.5 EPT:C ratio is intended to be assessed independently at each sample point. EPA commented that identification of instream sample sites (locations) and frequency of monitoring and sampling methods would be helpful. Figure 3 has been added with the intent to provide sample locations. Assessment methods are identified in Section IV., PROBLEM IDENTIFICATION. A single set of field observations and sampling was completed in 1996. Comments received from EJ noted that the TMDL contained several references to stream reach 5. Preliminary work in he drainage was planned to provide assessment data to characterize five discrete segments. Subsequent analysis indicated that there is no substantive difference relative to riparian vegetation, sediment particle size distribution or the macroinvertebrate community present in the two reaches located at the bottom of the drainage. Subsequently these two reaches were consolidated into a single reach, reach 1. The reaches further up-drainage were re-numbered to reflect this change. References to reach 5 which appeared in Section IV., PROBLEM IDENTIFICATION, and Section VIII., TOTAL MAXIMUM DAILY LOAD, have been corrected. EPA and EJ noted that there had been no quantification of relative sediment load associated with different land uses within the watershed. Both also commented that the 14

TMDL identified specific targets relative to reduction of sediment contribution from roads within the watershed and did not identify specific targets or mechanisms to mitigate sediment contribution from grazing or timber harvest. The TMDL concludes that the road system represents, to an overwhelming extent, the most significant source of sediment within the watershed. The most severe problems within the drainage are documented below road 331 in the lower end of reach 4 and roads 556 and 556 J higher in reach 4. It is believed that implementation of the road treatments described in the TMDL will, in and of themselves, result in attainment of the aquatic life standard. Grazing has historically occurred in areas throughout the watershed. The most apparent effect of grazing within the Box Canyon Creek watershed is the degradation of riparian vegetation observed in reach 1. Reach 1, however, exhibits no apparent aquatic community effect as a result. Nonetheless a specific remedy to this situation, installation of drift fencing, has been identified to address this problem. Grazing in the uplands has resulted in a degraded range condition which may contribute to the sediment load to Box Canyon Creek. This load is judged to be relatively insignificant relative to loading from the road system. Nonetheless the Forest Service will condition future Allotment Management Plans so as to incorporate requirements intended to improve range condition and reduce any sediment load from livestock grazing. No logging has occurred in the portion of the watershed tributary to reach 4. Some historic timber harvest has taken place to the east of reach 3 and may contribute sediment to that portion of the drainage. Most of prior timber cutting has occurred in areas tributary to reaches 1 and 2. Any impacts associated with timber harvest in those areas are not evident instream as reaches 1 and 2 have been utilized to develop the aquatic life and substrate water quality targets for the TMDL. Because the road system represents the most significant source of sediment within the watershed there has been no quantification of loading by land use. There has been no empirical modeling of sediment contribution by source or of the anticipated attainment of the aquatic life standard as a result of road system improvements. The TMDL is based upon best professional judgement. There are no point source discharges within the drainage, therefore there is no WLA component to the TMDL. The TMDL anticipates the loading reductions associated with road system treatments will be adequate to result in attainment of the aquatic life standard. Essentially, the LA components associated with grazing and timber harvest are determined to be insignificant. Sediment contributions from the road system represent the substantive portion of the LA. The quantity of sediment loading reduction which will be realized with implementation of the road system treatments represents the reduction in the LA component which will be necessary to attain the aquatic life standard. The MOS component of the TMDL is discussed in Section VIII. TOTAL MAXIMUM DAILY LOAD. The Forest Service has, in fact, approved the Lucy Timber Sale. The EA identifies a variety of management requirements and mitigation measures which will be required as 15

part of timber harvest activities. Many mitigation requirements are intended to prevent additional sediment loading associated with timber harvest. No timber harvest will be located in areas which are considered at risk of adding sediment to Box Canyon streamcourses (EA, page 27). Specific operational requirements are discussed in Chapter II of the EA.

16