Water, Air, & Soil Pollution

, Volume 223, Issue 9, pp 5759–5771 | Cite as

Critical Loads of Acidity to Protect and Restore Acid-Sensitive Streams in Virginia and West Virginia

  • Timothy J. SullivanEmail author
  • Bernard J. Cosby
  • Todd C. McDonnell
  • Ellen M. Porter
  • Tamara Blett
  • Richard Haeuber
  • Cindy M. Huber
  • Jason Lynch


The purpose of the research described here is to apply a new approach for generating aquatic critical load (CL) and exceedance calculations for an important acid-sensitive region of the eastern USA. A widespread problem in regional aquatic acidification CL modeling for US ecosystems has been the lack of site-specific weathering data needed to derive accurate model CL estimates. A modified version of the steady-state water chemistry CL model was applied here to estimate CL and exceedances for streams throughout acid-sensitive portions of Virginia and West Virginia. A novel approach for estimating weathering across the regional landscape was applied, based on weathering estimates extracted from a well-tested, process-based watershed model of drainage water acid–base chemistry and features of the landscape that are available as regional spatial data coverages. This process allowed extrapolation of site-specific weathering data from 92 stream watersheds to the regional context in three ecoregions for supporting CL calculations. Calculated CL values were frequently low, especially in the Blue Ridge ecoregion where one-third of the stream length had CL < 50 meq/m2/year to maintain stream ANC at 50 μeq/L under steady-state conditions. About half or more of the stream length in the study region was in exceedance of the CL for long-term aquatic resource protection under assumed nitrogen saturation at steady state. Land managers and air quality policy makers will need this information to better understand responses to air pollution emissions reductions and to develop ecoregion-specific air pollution targets.


Critical load Acidification Stream Weathering Virginia West Virginia 



We thank J. Charles, S. Mackey, G. McPherson, K. Snyder, and D. Moore for technical assistance and J. Karish for fiscal and project management support. R. Dennis provided CMAQ model output for dry sulfur and nitrogen deposition. Interpolated NADP wet deposition estimates were provided by J. Grimm. This research was supported through Cooperative Agreement Number H4506070713, awarded by the National Park Service of the US Department of the Interior to the University of Virginia, and through a contract between the US Forest Service and E&S Environmental Chemistry, Inc. This report has not been subjected to federal agency review, and no official endorsement is implied.

Supplementary material

11270_2012_1312_MOESM1_ESM.doc (216 kb)
ESM 1 (DOC 216 kb)


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Copyright information

© Springer Science+Business Media B.V. 2012

Authors and Affiliations

  • Timothy J. Sullivan
    • 1
    Email author
  • Bernard J. Cosby
    • 2
  • Todd C. McDonnell
    • 1
  • Ellen M. Porter
    • 3
  • Tamara Blett
    • 3
  • Richard Haeuber
    • 4
  • Cindy M. Huber
    • 5
  • Jason Lynch
    • 4
  1. 1.E&S Environmental Chemistry, Inc.CorvallisUSA
  2. 2.Department of Environmental ScienceUniversity of VirginiaCharlottesvilleUSA
  3. 3.Air Resources DivisionNational Park ServiceDenverUSA
  4. 4.Clean Air Markets DivisionUS Environmental Protection AgencyWashingtonUSA
  5. 5.USDA Forest ServiceRoanokeUSA

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