National Park Service


Date of this Version



Natural Resource Report NPS/NRPC/ARD/NRR 2011/369 / NPS 920/107405, April 2011: 27 pages

Published by the Department of the Interior, National Park Service, Natural Resource Program Center, Denver, Colorado

Also available at:

Please cite this publication as:

Sullivan, T. J., G. T. McPherson, T. C. McDonnell, S. D. Mackey, and D. Moore. 2011. Evaluation of the sensitivity of inventory and monitoring national parks to acidification effects from atmospheric sulfur and nitrogen deposition: Northern Great Plains Network (NGPN). Natural Resource Report NPS/NRPC/ARD/NRR—2011/369. National Park Service, Denver, Colorado.


United States government work. Public domain material.


Northern Great Plains Network (NGPN)

National maps of atmospheric sulfur (S) and nitrogen (N) emissions and deposition are provided in Maps A through D as context for subsequent network data presentations. Maps A and B show county level emissions of total S and total N for the year 2002. Maps C and D show total S and total N deposition, again for the year 2002.

There are three parks in the Northern Great Plains Network that are larger than 100 square miles: Badlands (BADL), Missouri (MNRR), and Theodore Roosevelt (THRO). In addition, there are 10 smaller parks.

Total annual S and N emissions, by county, are shown in Maps E and F for lands in and surrounding the Northern Great Plains Network. County-level S emissions were low, in most areas less than 1 ton per square mile per year. There were scattered pockets of higher S emissions (Map E) within the network, including the region around Knife River Indian Villages NHS (KNRI). Annual county-level N emissions were somewhat higher, ranging from less than 1 ton per square mile to between 5 and 20 tons per square mile. In general, annual county N emissions were less than 5 tons per square mile throughout most of the network. Point source emissions of SO2 and oxidized (nitrogen oxides, NOx) and reduced (ammonia, NH3) N are shown in Maps G and H, respectively. Point sources of SO2 were few, and most emitted less than 5,000 tons of S per year. There were several point sources of oxidized N, and one point source of reduced N, within the network that were larger than about 2,000 tons per year.

Urban centers within the network and within a 300-mile buffer around the network are shown in Map I. There are relatively few urban centers of any magnitude within this network, although Denver is close to the southwestern network boundary.

Total S and total N deposition in and around the network are shown in Maps J and K, respectively. Included in this analysis are both wet and dry forms of deposition and both the oxidized and reduced N species. Total S deposition in this network was generally low, less than 2 kg S/ha/yr in most portions of the network. There were a few areas with higher S deposition, most of them in the northern and eastern parts of the network. Total N deposition within the network ranged from as low as 2 to 5 kg N/ha/yr in the northwest to greater than 10 kg N/ha/yr in the southeast. Most of the I&M parks in this network were located within the lower N deposition zone.

Land cover in and around the network is shown in Map L. The predominant cover types within this network are generally grassland/herbaceous, row crop, and pasture/hay.

Watershed slope for parks in the network is shown in Map M. The slope in most of the parks varies from less than 10o to between 10° and 20°. One park (Mount Rushmore [MORU]) has steeper terrain, between 20° and 30°.

Park lands requiring special protection against potential adverse impacts associated with acidic deposition are shown on Map N. Also shown on Map N are all federal lands designated as wilderness, both lands managed by NPS and lands managed by other federal agencies. The land designations used to identify this heightened protection included Class I designation under the Clean Air Act Amendments and wilderness designation. There is very limited Class I or wilderness area within this network.

Network rankings are given in Figures A through C as the average ranking of the Pollutant Exposure, Ecosystem Sensitivity, and Park Protection metrics, respectively. Figure D shows the overall network Summary Risk ranking. In each figure, the rank for this particular network is highlighted to show its relative position compared with the ranks of the other 31 networks.

The Northern Great Plains Network ranked in the middle quintile among networks in Pollutant Exposure (Figure A). Sulfur and N emissions and deposition within the network were moderate. The network Ecosystem Sensitivity was also ranked as Moderate (Figure B). This network ranked in the second lowest quintile in Park Protection, having limited amounts of protected lands (Figure C).

In combination, the network rankings for Pollutant Exposure, Ecosystem Sensitivity, and Park Protection yielded an overall Network Risk ranking that is below the middle of the distribution among networks (Figure D). The overall level of concern for acidification effects on I&M parks within this network is considered Moderate.

Similarly, park rankings are given in Figures E through H for the same metrics. In the case of the park rankings, we only show in the figures the parks that are larger than 100 square miles. Relative ranks for all parks, including the smaller parks, are given in Table A and Appendix A. As for the network ranking figures, the park ranking figures highlight those parks that occur in this network to show their relative position compared with parks in the other 31 networks. Note that the rankings shown in Figures E through H reflect the rank of a given park compared with all other parks, irrespective of size.

Park-specific Pollutant Exposure rankings for the three parks in this network that are larger than 100 square miles are shown in Table A and Figure E. Two of these large parks, MNRR and THRO, were ranked Moderate for this theme; BADL was ranked Very Low. Pollutant Exposure for each of the smaller parks was ranked in the second lowest or middle quintile. For Ecosystem Sensitivity, Wind Cave (WICA) was the only park ranked in the highest quintile. Jewel Cave (JECA) was ranked in the second highest quintile. All of the larger parks were ranked in the middle quintile (Moderate) for Ecosystem Sensitivity (Figure F). The rest of the parks were ranked Moderate to Very Low for this theme. BADL, THRO, and WICA were in the highest quintile in Park Protection; Mount Rushmore (MORU) and Niobrara (NIOB) were in the second highest. The other parks, including MNRR, were ranked in the middle quintile for Park Protection (Figure G, Table A).

For the larger parks, the overall park Summary Risk ranking for THRO was High, and for BADL and MNRR was Moderate (Figure H). Among the smaller parks, the Summary Risk ranking was High for WICA, Low for Fort Union (FOUS) and KNRI, and Moderate for the others (Table A).