U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2008–3028

April 2008

Environmental Monitoring and Assessment Program Western Pilot 

Project—Conditions of North Dakota Perennial Streams for Water 

Chemistry and Mercury in Fish Tissue, 2000–2003

Kevin C. Vining and Robert F. Lundgren

Summary

Sixty-five sampling sites, selected by a statistical design to represent lengths of perennial streams in North 

Dakota, were chosen to be sampled for water chemistry and mercury in fish tissue to establish unbiased baseline 

data. From the assessment of all water chemistry constituents, the percentage of stream length considered to be 

in poor condition was greater in the Rangeland Plains than in the Cultivated Plains. About 30 percent of perennial stream length in North Dakota was considered to be in good condition on the basis of mercury concentrations in fish tissue.

Introduction

The Environmental Monitoring and Assessment Program 

Western Pilot Project (EMAP-West) was undertaken in North 

Dakota from 2000 to 2003 to develop tools that could be used to 

produce unbiased estimates of ecological conditions of perennial streams in the State. The EMAP-West for North Dakota 

was a cooperative effort by the U.S. Environmental Protection 

Agency (USEPA), the U.S. Geological Survey, and the North 

Dakota Department of Health (NDDH). Information from 

the EMAP-West was used to establish baseline data that can 

be compared with data obtained from future monitoring and 

sampling activities. This fact sheet provides information about 

EMAP-West sampling activities in North Dakota and the conditions of streams on the basis of water chemistry and mercury in 

fish tissue in ecological regions of the State during 2000–2003.

Ecoregions of North Dakota

Ecological regions (ecoregions) have been loosely defined 

as the spatial representations of the interrelations of natural 

and human factors (Omernik, 1987). In North Dakota, natural 

vegetation, predominately prairie grass and a patchwork of 

forests along streams, was established on a variety of soils and 

topography. Since European settlement, considerable animal 

production, consisting mostly of cattle, and agricultural production of crops, including wheat, barley, sunflowers, canola, sugar 

beets, soybeans, and corn, has developed across the State. All 

these factors contribute to the delineation of ecoregions of North 

Dakota.

North Dakota is covered by four level III ecoregions as 

defined by Bryce and others (1998): the Northwestern Great 

Plains, the Northwestern Glaciated Plains, the Northern Glaciated Plains, and the Lake Agassiz Plain (fig. 1). In another 

ecological assessment (Stoddard and others, 2005), the USEPA 

indicated that North Dakota exists within two broader regions: 

the Cultivated Plains, a flat to gently rolling landscape that has 

many wetlands and streams, and the Rangeland Plains, a rolling 

to hilly landscape that has many wetlands but few streams in the 

northeast and few wetlands but many streams in the southwest 

(fig. 1).

EMAP-West Sampling Sites

Sampling sites were selected randomly by a USEPA 

statistical design (U.S. Environmental Protection Agency, 

2000) to represent lengths of perennial streams in North Dakota 

from which unbiased baseline data would be collected. Of the 

65 sites chosen for sampling (fig. 1), 63 sites were sampled for 

water chemistry and 49 sites were sampled for mercury in fish 

tissue. Samples could not be collected at the other sites because 

stream conditions were unacceptable or the number of fish was 

insufficient. Of the approximately 4,280 perennial stream miles 

within the State, 4,080 miles were represented in the assessment of water chemistry (2,450 miles in the Cultivated Plains 

and 1,630 miles in the Rangeland Plains). For North Dakota as 

a whole, about 3,790 miles of stream length was represented by 

the assessment of mercury in fish tissue. EMAP-West protocols 

for water chemistry and mercury in fish tissue sampling are 

explained in the Field Operations Manual for Wadeable Streams 

for EMAP-West (Peck and others, 2006).
Missouri

River

NORTH DAKOTA

Northwestern

Great Plains

Northwestern

Glaciated Plains

Northern Glaciated Plains

Lake

Agassiz

Plains

0

0

50

50

100 MILES

100 KILOMETERS

104° 102° 100° 98° 49°

48°

48°

47°

EXPLANATION

Cultivated Plains

Rangeland Plains

Sampling site

 Site visited; water-chemistry and fish-tissue samples collected

 Site visited; no samples collected because of unacceptable

 stream conditions

 Site visited; water-chemistry samples collected, but no 

 fish-tissue samples collected because number of fish

 was insufficient

Figure 1. Ecoregions and EMAP-West sites used 

for sampling water chemistry and mercury in fish 

tissue in North Dakota (adapted from Tom Johnson, 

USEPA, written commun., 2007).

Stream Condition Threshold Values

The NDDH used USEPA statistical techniques on data 

from the analysis of water chemistry and of mercury in fish 

tissue to establish threshold values identifying good and poor 

stream conditions (Stoddard and others, 2005). Threshold 

values were established for the water-chemistry constituents 

total phosphorus, total nitrogen, and specific conductance, and 

for mercury in fish tissue (table 1). Threshold values for total 

phosphorus, total nitrogen, and mercury in fish tissue were the 

same as those used in an assessment of South Dakota perennial streams (Heakin and others, 2006), and the thresholds 

for specific conductance were the same as those used in an 

EMAP-West report (Stoddard and others, 2005). Thresholds 

for fair stream conditions were determined to fall between the 

thresholds for poor and good stream conditions. The threshold 

values for mercury in fish tissue are regional indicators selected 

for wildlife assessment (Lazorchak and others, 2003) and do not 

necessarily correspond to human health concerns.

Stream Condition Assessments

Assessments of water-chemistry conditions for perennial 

streams in the Cultivated Plains of North Dakota are shown 

in figure 2. An estimated 1,020 miles (42 percent) of stream 

length was considered to be in poor condition with regards to 

total phosphorus; 1,000 miles (41 percent) of stream length was 

considered to be in good condition. Approximately 148 miles 

(6 percent) and 231 miles (9 percent) of stream length was considered to be in poor condition on the basis of total nitrogen and 

specific conductance, respectively. Approximately 2,300 miles 

(94 percent) of stream length was considered to be in either 

fair or good condition on the basis of total nitrogen, and 

approximately 2,220 miles (91 percent) of stream length was 

considered to be in either fair or good condition on the basis of 

specific conductance.

Assessments of water-chemistry conditions for perennial 

streams in the Rangeland Plains of North Dakota are shown 

in figure 3. An estimated 639 miles (39 percent) of stream 
Figure 2. Stream lengths, in miles, in the Cultivated Plains that were considered to be in good, fair, and poor 

condition on the basis of total phosphorus, total nitrogen, and specific conductance.

0 200 400 600 800 1,000 1,200 1,400 1,600 1,800

SPECIFIC 

CONDUCTANCE

TOTAL 

NITROGEN

TOTAL 

PHOSPHORUS

STREAM LENGTH, IN MILES

Good

Fair

Poor

length was considered to be in poor condition on the basis of 

total phosphorus; 774 miles (48 percent) of stream length was 

considered to be in good condition. An estimated 297 miles 

(18 percent) and 744 miles (46 percent) of stream length were 

considered to be in poor condition on the basis of total nitrogen and specific conductance, respectively. Approximately 

1,330 miles (82 percent) of stream length was considered to be 

in either fair or good condition on the basis of total nitrogen, 

and about 885 miles (54 percent) of stream length was considered to be in either fair or good condition on the basis of specific conductance. From the assessments of all water-chemistry 

constituents, the percentage of stream length considered to be in 

poor condition was greater in the Rangeland Plains than in the 

Cultivated Plains.

Assessments of mercury in fish tissue for perennial streams 

in North Dakota are shown in figure 4. Results indicated about 

2,140 miles (56 percent) of stream length in North Dakota had 

mercury concentrations greater than 0.1 μg/g and was considered to be in poor condition. About 1,140 miles (30 percent) 

of stream length in North Dakota was considered to be in good 

condition.

References

Bryce, S.A., Omernik, J.M., Pater, D.E., Ulmer, M., Schaar, J., 

Freeouf, J., Johnson, R., Kuck, P., and Azevedo, S.H., 1998, 

Ecoregions of North Dakota and South Dakota: Northern 

Prarie Wildlife Research Center, Jamestown, North Dakota, 

accessed August 2007 at http://www.npwrc.usgs.gov/

resource/habitat/ndsdeco/index.htm

Heakin, A.J., Neitzert, K.M., and Shearer, J.S., 2006, Summary of Environmental Monitoring and Assessment Program 

(EMAP) activities in South Dakota, 2000–2004: U.S. Geological Survey Scientific Investigations Report 2006–5007, 

45 p.

Lazorchak, J.M., McCormick, F.H., Henry, T.R., and Herlihy, 

A.T., 2003, Contamination of fish in streams of the MidAtlantic Region—an approach to regional indicator selection and wildlife assessment: Environmental Toxicology and 

Chemistry, v. 22, p. 545–553. 

Table 1. Threshold water-constituent and mercury values used to determine perennial stream-condition classes of poor and good.

[>, greater than; μg/L, micrograms per liter; <, less than; μS/cm, microsiemens per centimeter; ≤, less than or equal to; μg/g, micrograms per gram]

Cultivated Plains Rangeland Plains

Chemical stressor Poor condition threshold Good condition threshold Poor condition threshold Good condition threshold

Total phosphorus >312 μg/L <228 μg/L >138 μg/L <70 μg/L

Total nitrogen >2,500 μg/L <1,520 μg/L >1,190 μg/L <886 μg/L

Specific conductance >2,000 μS/cm ≤1,000 μS/cm >2,000 μS/cm ≤1,000 μS/cm

North Dakota (as a whole)

Mercury in fish tissue >0.1 μg/g ≤0.1 μg/g >0.1 μg/g ≤0.1 μg/g
Figure 4. Stream lengths, in miles, in North Dakota as a whole that were considered to be in good and poor condition on the 

basis of mercury in fish tissue, and the stream length that was not assessed.

Figure 3. Stream lengths, in miles, in the Rangeland Plains that were considered to be in good, fair, and poor 

condition on the basis of total phosphorus, total nitrogen, and specific conductance.

0 200 400 600 800 1,000 1,200 1,400 1,600 1,800

SPECIFIC 

CONDUCTANCE

TOTAL 

NITROGEN

TOTAL 

PHOSPHORUS

STREAM LENGTH, IN MILES

Good

Fair

Poor

0 500 1,000 1,500 2,000 2,500

POOR

NOT ASSESSED

GOOD

STREAM LENGTH, IN MILES

Omernik, J.M., 1987, Ecoregions of the conterminous United 

States: Annals of the Association of American Geographers, 

v. 77, no. 1, p. 118–125.

Peck, D.V., Herlihy, A.T., Hill, B.H., Hughes, R.M., Kaufmann, 

P.R., Klemm, D.J., Lazorchak, J.M., McCormick, F.H., 

Peterson, S.A., Ringold, P.L., Magee, T., and Cappaert, M.R., 

2006, Environmental Monitoring and Assessment ProgramSurface Waters Western Pilot Study—field operations manual 

for wadeable streams: EPA Report EPA/620/R-06/003, U.S. 

Environmental Protection Agency, Office of Research and 

Development, Washington, D.C. [variously paged].

Stoddard, J.L., Peck, D.V., Olsen, A.R., Paulsen, S.G., Van 

Sickle, J., Herlihy, A.T., Kaufmann, P.R., Hughes, R.M., 

Whittier, T.R., Lomnicky, G., Larsen, D.P., Peterson, S.A., 

and Ringold, P.L., 2005, An ecological assessment of western 

streams and rivers: U.S. Environmental Protection Agency, 

Oregon State University, and Dynamac Corporation, Corvallis, Oregon, 49 p.

U.S. Environmental Protection Agency, 2000, MidAtlantic Highlands Streams Assessment: EPA Report 

EPA/903/R-00/015, Washington, D.C., 64 p.