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How are these data used?

Water samples are used to collect data for four chemical and two human health indicators.

Human Health

A river that appears green due to algal growth. Photo by National Park Service, public domain.

Phosphorus, like nitrogen, is an essential
nutrient found in rivers and streams. Excess phosphorus can stimulate overgrowth of algae, cyanobacteria (which can produce toxins) and aquatic plants. These may result in algal blooms, low dissolved oxygen levels, or degraded conditions for macroinvertebrates and
other aquatic life.

Where are phosphorus samples collected?

Crews collect phosphorus
samples at the midpoint
of the sample reach.

To learn more, see the
NRSA Field Operations Manual.