The URL can be used to link to this page

Home My WebLink AboutTN ANC Addendum TMDL North Carolina Addendum to the Low pH TMDL for the Great Smoky Mountains National Park, TN August, 2012 Waterbody IDs: 2-79-(24)ut4 7-10 Submitted by: NC Department of Environment and Natural Resources Division of Water Quality 1617 Mail Service Center Raleigh NC 27699-1617 Addendum to the Low pH TMDL for the Great Smoky Mountains National Park, TN 2 Introduction The Tennessee Department of Environment and Conservation developed a Total Daily Maximum Load (TMDL) for the Great Smoky Mountains National Park in 2010 to address low pH impairments. The TMDL was approved by EPA Region 4 on September 7, 2010. This addendum to the Great Smoky Mountains TMDL is to address additional assessment units on the 303(d) list for low pH impairments in the mountains of North Carolina. These assessment units drain forested areas at high elevations in western North Carolina and were first included on the 303(d) list in 2010. The impaired waters and associated assessment units (AUs) are shown below: Waterbody Name [Assessment Unit] Description Water Quality Classification Miles Unnamed tributary to Tuckasegee River [2-79-(24)ut4] Source to Tuckasegee River C 1.3 Hollow Poplar Creek [7-10] From source to Nolichucky River C; Tr 5.6 Area Description Both waterbodies are located in the Blue Ridge Mountains of western North Carolina and drain high altitude ridges in predominantly forested watersheds. The tributary to the Tukasegee River is located in Jackson County and drains the northern slope of Cullowhee Mountain from an elevation of approximately 4,000 feet (Figure 1). Poplar Hollow Branch is located in Mitchell County and drains the southern slope of Unaka Mountain from an elevation of approximately 5,000 feet (Figure 2). There are no NPDES wastewater or stormwater permits in these watersheds. Addendum to the Low pH TMDL for the Great Smoky Mountains National Park, TN 3 Figure 1 - Unnamed Tributary to the Tuckasegee River G4210000 Addendum to the Low pH TMDL for the Great Smoky Mountains National Park, TN 4 Figure 2 - Hollow Poplar Creek Documentation of Impairment The two addendum assessment units in the North Carolina mountains were listed in Category 5 of the 2010 North Carolina Integrated Report for low pH. These streams do not meet their designated uses. Waters within this classification, according to 15A NCAC 02B.0221 (Fresh Surface Water Quality Standards for Class C Waters), must meet the following water quality criteria for pH in order to meet their designated use: “pH shall be normal for the waters in the area, which generally shall range between 6.0 and 9.0 except that swamp waters may have a pH as low as 4.3 if it is the result of natural conditions.” Data collected on these streams through the NC Random Ambient Monitoring System is shown in Appendix A. Low pH in western North Carolina streams has been documented by others as well. Recent USDA Forest Service surveys have shown widespread occurrence of streams having low acid neutralizing capacity (ANC) and pH in the mountains of western North Carolina, attributable to deposition of sulfur and nitrogen compounds from the atmosphere. Modeling has been performed to estimate the sensitivity of watersheds in the Southern Blue Ridge province to E9993000 Addendum to the Low pH TMDL for the Great Smoky Mountains National Park, TN 5 changes in atmospheric sulfur deposition (Sullivan et al. 2007). US National Park Service is funding a similar project, Application of a Dynamic Watershed Biogeochemical Model (PnET- BGC) to Evaluate the Recovery of Sensitive Aquatic Resources at Great Smoky Mountains National Park From the Effects of Acidic Deposition. Data collected by the US National Park Service in the Great Smoky Mountains National Park is shown in Appendix B. A partnership among state and Federal agencies and universities continues toward TMDL implementation, with efforts underway to quantify sources and emissions reductions needed to increase stream ANC in these higher elevations in Tennessee and North Carolina. Scenarios of pollution, climate trends, and resulting stream pH will be modeled. Results will let the Park, and state and federal regulators know what reductions in sulfate and nitrate emissions are needed. TMDL Reductions The 2010 Great Smoky Mountains TMDL (http://tn.gov/environment/wpc/tmdl/approvedtmdl/gsm_ph.pdf) requires instream ANC of 6- 50 μeq/L. These targets are also appropriate for the addendum assessment units and other forested high elevation streams in western North Carolina, in order for the streams to achieve and maintain the pH standard. Full implementation of the 2010 Great Smoky Mountains TMDL and achievement of the ANC targets of 6-50 μeq/L is expected to achieve water quality standards in the addendum waters. DWQ may reevaluate the need for individual TMDLs for the addendum waters if the required targets are determined to be insufficient. Public Participation The 2010 Great Smoky Mountains TMDL was placed on Public Notice for a 60-day period. Notice was given via the following: Tennessee Department of Environment and Conservation website, TN NPDES permit Public Notice mailing, and letter sent to water quality partners. A draft of this addendum to the Great Smoky Mountains TMDL was publicly noticed through electronic notification of the draft addendum to known interested parties. The addendum was available on the DWQ’s website at http://portal.ncdenr.org/web/wq/ps/mtu/tmdl/tmdls during the comment period, August 2-21, 2012. Addendum to the Low pH TMDL for the Great Smoky Mountains National Park, TN 6 Literature Cited Sullivan, T.J., Cosby, B.J., Snyder, K.U., Herlihy, A.T., Jackson, B., 2007. Model-based Assessment of the Effects of Acidic Deposition on Sensitive Watershed Resources in the National Forests of North Carolina, Tennessee, and South Carolina. Final report prepared for USDA Forest Service, Asheville. NC. E&S Environmental Chemistry, Inc., Corvallis, OR. Addendum to the Low pH TMDL for the Great Smoky Mountains National Park, TN 7 Appendix A: NC Random Ambient Monitoring System (RAMS) Data NC RAMS Data G4210000 - UT to Tuckasegee River E9993000 - Hollow Poplar Creek Date pH measured Date pH Measured 3/21/2007 6.8 3/28/2007 6.3 4/23/2007 6.7 5/9/2007 6.2 5/29/2007 6.5 6/12/2007 6.6 6/25/2007 6.4 7/10/2007 6.4 7/24/2007 6.5 8/21/2007 6.7 8/29/2007 6.7 9/26/2007 6.3 9/12/2007 6.4 10/17/2007 5.8 11/12/2007 6.4 11/13/2007 6.2 12/11/2007 6.6 12/14/2007 6.0 1/21/2008 5.6 1/7/2008 6.3 1/29/2008 5.9 2/25/2008 6.4 2/11/2008 5.7 3/6/2008 5.9 3/24/2008 6.7 4/11/2008 6.6 4/30/2008 6.5 5/13/2008 7.1 5/30/2008 6.3 6/18/2008 6.9 6/16/2008 7.4 8/26/2008 5.8 7/29/2008 6.4 9/11/2008 6.0 8/20/2008 5.8 10/8/2008 6.7 9/24/2008 6.6 11/3/2008 6.4 10/15/2008 6.6 12/3/2008 5.3 11/5/2008 6.2 12/16/2008 6.0 Average* 6.2 6.1 Minimum 5.6 5.3 Maximum 7.4 7.1 * Average pH values were calculated by taking the mean of the hydrogen ion concentration for the dataset, then converting the value back to pH Addendum to the Low pH TMDL for the Great Smoky Mountains National Park, TN 8 Appendix B: US National Park Service Sampling Locations and Data Addendum to the Low pH TMDL for the Great Smoky Mountains National Park, TN 9 pH Station/Parameter Data Period Data Points Average Min Max GRSM_F_0127 1993-2003 42 6.4 6.0 6.8 GRSM_F_0142 1994-2008 69 6.5 5.9 6.9 GRSM_F_0143 1994-2008 71 6.4 5.6 7.0 GRSM_F_0144 1993-2008 70 6.5 5.5 6.9 GRSM_F_0147 1993-2008 87 6.6 6.1 7.1 GRSM_F_0148 1993-2008 64 6.7 6.3 7.2 GRSM_F_0149 1993-2008 63 6.6 6.2 7.1 GRSM_F_0150 1993-2003 35 6.6 6.3 7.1 GRSM_F_0221 1993-2008 37 6.2 5.6 6.6 GRSM_F_0224 2004-2008 8 6.3 5.9 6.8 GRSM_F_0251 1993-2008 87 6.1 5.6 6.6 GRSM_F_0252 1993-2008 73 5.4 4.6 7.0 GRSM_F_0266 1993-2003 35 6.5 6.1 7.0 GRSM_F_0268 1994-2008 73 6.5 6.0 7.0 GRSM_F_0270 2004-2008 28 6.4 5.9 6.8 GRSM_F_0290 1994-2003 24 5.1 4.4 6.2 GRSM_F_0291 1994-2003 42 6.1 5.6 6.7 GRSM_F_0293 1993-2008 91 6.6 6.2 7.1 GRSM_F_0310 1993-2008 49 6.5 6.0 7.1 GRSM_F_0311 1993-2008 42 6.5 6.1 6.9 GRSM_F_0336 1995-2003 41 6.4 6.1 6.8 GRSM_F_0337 1995-2003 45 6.3 5.9 6.7 GRSM_F_0479 1996-2008 38 6.5 6.0 7.0 GRSM_F_0480 1996-2008 37 6.5 6.1 7.1 GRSM_F_0481 1996-2008 36 6.5 6.1 7.0 GRSM_F_0482 1996-2008 35 6.5 6.1 7.1 GRSM_F_0483 1996-2008 37 6.6 6.1 7.1 GRSM_F_0484 1996-2008 36 6.4 6.0 6.9 GRSM_F_0485 1996-2008 36 6.5 6.1 7.0 GRSM_F_0493 1996-2008 55 6.5 6.1 7.0 GRSM_ND_NE 1991-2008 656 5.6 3.5 8.4 GRSM_ND_SW 1991-2008 657 5.8 3.3 8.0 Totals 2805 6.1 3.3 8.4 Addendum to the Low pH TMDL for the Great Smoky Mountains National Park, TN 10 Acid Neutralizing Capacity (ueq/L) Station Data Period Data Points Average Min Max GRSM_F_0127 1993-2003 42 47.03 19.47 86.67 GRSM_F_0142 1994-2008 69 58.80 31.22 147.40 GRSM_F_0143 1994-2008 71 50.34 15.53 105.74 GRSM_F_0144 1993-2008 69 54.12 26.26 95.13 GRSM_F_0147 1993-2008 87 85.02 39.62 126.60 GRSM_F_0148 1993-2008 64 123.56 66.84 216.29 GRSM_F_0149 1993-2008 63 82.39 41.76 124.05 GRSM_F_0150 1993-2003 35 79.35 39.09 113.10 GRSM_F_0221 1993-2008 37 29.18 2.12 66.22 GRSM_F_0224 2004-2008 8 45.40 28.98 67.83 GRSM_F_0251 1993-2008 87 22.43 -3.27 63.85 GRSM_F_0252 1993-2008 73 21.58 -21.22 746.60 GRSM_F_0266 1993-2003 35 74.23 40.27 159.74 GRSM_F_0268 1994-2008 73 62.54 23.36 178.00 GRSM_F_0270 2004-2008 28 47.44 25.51 73.43 GRSM_F_0290 1994-2003 24 -4.04 -40.51 32.51 GRSM_F_0291 1994-2003 42 25.61 3.75 61.94 GRSM_F_0293 1993-2008 90 86.20 45.70 133.20 GRSM_F_0310 1993-2008 49 77.64 44.05 173.80 GRSM_F_0311 1993-2008 42 67.18 36.37 162.76 GRSM_F_0336 1995-2003 41 49.71 32.15 118.02 GRSM_F_0337 1995-2003 46 41.60 20.89 67.99 GRSM_F_0479 1996-2008 38 69.11 41.34 106.43 GRSM_F_0480 1996-2008 37 86.16 64.65 137.80 GRSM_F_0481 1996-2008 36 87.46 55.43 153.91 GRSM_F_0482 1996-2008 35 90.32 64.18 156.26 GRSM_F_0483 1996-2008 37 87.39 45.23 165.02 GRSM_F_0484 1996-2008 36 56.23 32.65 138.33 GRSM_F_0485 1996-2008 36 72.60 40.26 139.69 GRSM_F_0493 1996-2008 55 70.84 30.55 143.50 GRSM_ND_NE 1991-2008 649 4.06 -21.57 35.82 GRSM_ND_SW 1991-2008 651 11.60 -13.79 51.85 Totals 2791 37.12 -40.51 746.60 Addendum to the Low pH TMDL for the Great Smoky Mountains National Park, TN 11 Appendix C: Public Comments and Responses 1 Addendum to the Low pH TMDL for the Great Smoky Mountains National Park, TN Public Comment Responsiveness Summary August 2012 The public comment period extended from August 2, 2012 through August 21, 2012. Comments were received from the North Carolina Department of Transportation. These comments with the NC Division of Water Quality responses are provided in the Responsiveness Summary presented below. Response: The impairment is low pH, which although not a pollutant, is associated with state-adopted, EPA-approved instream numeric criteria. ANC is a common surrogate for pH in TMDLs. The low pH is attributable to sulfur dioxide and nitrogen oxide emissions from sources outside the TMDL area. The text has been revised for clarification. Response: The relationship between ANC and pH is controlled by well-defined aquatic equilibrium chemistry. ANC is an indicator related to both pH and NOx/SOx deposition. Sulfate and nitrate’s acidifying effects contribute to degradation of water quality by lowering the acid neutralizing capacity (ANC). As the ANC decreases, streams can acidify to the point where they are no longer capable of supporting aquatic life. 2 Response: The low pH is attributable to sulfur dioxide and nitrogen oxide emissions from (nonpoint) sources outside the TMDL area. The text has been revised for clarification. Response: The original TMDL included loads. Because this is an addendum to that TMDL, it is not necessary to include additional load calculations here. The primary purpose of the addendum is to acknowledge that full implementation of the TMDL is expected to achieve the water quality standard in the addendum streams. Response: See response to 4. above. A footnote for Table 5 in the Tennessee TMDL states: “The TMDL is also expressed in terms of minimum allowable water column concentration because TDEC recognizes that these values provide information that potentially will be more useful regarding TMDL implementation efforts than the values that are expressed in terms of an allowable load.” Further, the goal of the TMDL is a higher ANC than observed, and a higher pH than observed, so it would not be appropriate to express the goals as maxima. Response: The text has been revised for clarification. The targets are appropriate for meeting the pH water quality standard in 15A NCAC 2B .0200. 3 Response: Revisions have been made as suggested. Response: The original TMDL was made available for public comment for 60 days. We believed that a shorter review period would be adequate for this 10-page (including Appendices) Addendum. We will continue to make TMDLs available for comment for at least 30 days.