Red River of the North Basin
National Water-Quality Assessment Program
Tornes, L.H., Brigham, M.E., and Lorenz, D.L., 1997, Nutrients,
Suspended Sediment, and Pesticides in Streams in the Red River of the North
Basin, Minnesota, North Dakota, and South Dakota, 1993-95.
U.S. Geological Survey, Water-Resources Investigations Report 97-4053, 70 p.
Abstract
Fifteen stream sites in the Red River of the North Basin were sampled during
1993-95 to assess levels of nutrients, organic carbon, and suspended sediment,
and five sites were sampled for pesticides. Concentrations varied seasonally
and were related to periods of fertilizer and pesticide application, and to
runoff. Concentrations of several constituents were related to the
physiographic area the stream drains, but other factors such as local land use
frequently complicated that relation.
Median dissolved nitrogen concentrations were highest in streams influenced
by the Red River Valley Lake Plain physiographic area. Organic nitrogen
comprised the largest part of the dissolved nitrogen in streams. Ammonia was
negligible most of the year, but accumulated under ice in late winter. Nitrate
concentrations generally were highest during snowmelt and rainfall runoff.
Phosphorus in streams mostly was in the dissolved form, which is readily
available to biota. Streams draining the Moraine and Lake-Washed Till Plain
had the lowest concentrations of total phosphorus, while Drift Prairie and Red
River Valley Lake Plain streams had the highest concentrations. Concentrations
of both dissolved and suspended phosphorus increased substantially during
runoff of snowmelt and rainfall.
The Bois de Sioux River Basin had the highest nitrogen yield. High nitrogen
and phosphorus yields probably were related to agricultural practices in the
Bois de Sioux River Basin. High phosphorus concentrations in the Pembina River
probably result from agricultural practices and runoff from the steep terrain
in the basin.
Improved wastewater treatment appears to have reduced ammonia
concentrations in streams, but has resulted in increased nitrate
concentrations. The loads of nitrogen and phosphorus in the Red River of the
North during this study were about twice as high as historical loads, but
still were only about 4.1 and 2.4 percent, respec- tively, of the amounts
introduced to the study unit.
Dissolved organic carbon concentrations above 15 mg/L were common in
streams draining peatlands. Suspended organic carbon concentrations were
highly variable and generally were highest during runoff.
Most suspended sediment in streams was clay and silt sized particles. The
Pembina River had the highest concentrations and yields of suspended sediment,
probably the result of erosion along this relatively high-gradient
stream. Streams having an abundance of lakes, reservoirs, and wetlands in
their watersheds had the lowest sediment concentrations and yields.
Several pesticides were frequently detected. Atrazine and other triazine
compounds were detected in most stream-water samples throughout the
study. Concentrations of triazine herbicides were highest in streams draining
southern parts of the study unit where they are applied to corn. Triallate was
commonly detected in northern streams where it is applied to small grains and
sunflowers. Simazine and prometon were commonly detected, but generally are
used only for nonagricultural purposes. Few insecticides were detected in
stream-water samples. Carbofuran was the most commonly detected insecticide
and was found in 16 percent of the samples.
The most heavily used herbicides, 2,4-D and MCPA, were infrequently
detected in stream-water samples. Of the estimated applications of atrazine,
triallate, and 2,4-D, about 0.9, 0.06, and 0.02 percent of each of these
compounds, respectively, was carried out of the study unit by the Red River of
the North during 1993-95.
| 
U.S. Department of the Interior |
U.S. Geological Survey
