Scientists at NOAA,
and other agencies, such as the U.S. Geological Survey (USGS)
and the U.S. Environmental Protection Agency, sample sediments
through various long-term monitoring programs. One program,
the USGS National Water Quality Assessment program, has been
collecting and analyzing river sediment data across the country
since 1991. Scientists test for nutrients and pesticides
that are used in nearby agricultural, urban and suburban areas.