National Water-Quality Assessment (NAWQA) Program
Nutrients are chemical elements essential to plant and animal nutrition. The two most common nutrients, nitrogen and phosphorus, are the major component of fertilizers for houseplants, lawns and gardens, and agricultural crops. While essential to life in small amounts, in high concentrations these nutrients are considered contaminants.
In streams and reservoirs, an oversupply of nutrients leads to excessive growth of algae. Unsightly scums of algae on the surface of nutrient-enriched waters decrease recreational values and clog water intakes. Unseen problems occur as algae decay and decompose, removing most of the oxygen and making it difficult for fish and other aquatic life to survive. Nutrient enrichment and the problems it causes are known as "eutrophication."
In ground waters, nitrogen is the primary nutrient found at high levels, usually in the form of nitrate. Nitrate concentrations are generally higher in ground waters than surface waters, exceeding the U. S. Environmental Protection Agency's health standard more frequently. The standard exists to protect infants from drinking water high in nitrate, because they are susceptible to low-oxygen levels in blood as a result.
Scientific information about where, when, and how chemicals enter water supplies can help managers tailor protection strategies to fit the need, providing high quality water while minimizing costs. As the NAWQA program began, we sought advice on which contaminants were most important to focus on. There was almost unanimous agreement that nutrients were a widespread and longstanding issue.
The Nutrients National Synthesis is answering questions such as: