We know that excess nutrients in surface waters are a problem in many parts of the US, but improving the situation sometimes requires more information—and more authority—than we have available.
A publication by the US Geological Survey helps with the information aspect, at least. “Nutrients in the Nation’s Streams and Groundwater, 1992-2004” is a comprehensive assessment of the sources, distribution, and effects of nutrients throughout US waters. The 174-page publication, issued last year, covers the subject thoroughly, from a “nutrient primer” to chapters dealing with the transport of nutrients between surface water and groundwater, the distribution of nutrients, and potential effects on aquatic life and human health.
The report offers some perspective on the problem and, just as importantly, an indication of the questions we need to answer: What are the background levels of phosphorus and nitrogen? How much comes from application of fertilizers, from livestock, from phosphates in laundry detergent? (The latter is not as big a problem now as it was before phosphate detergents began to be phased out in the 1970s, but for decades before that, detergents were one of the main sources of phosphorus in the environment.) Are low dissolved oxygen levels in surface waters the result of nutrients and algae blooms, or something else?
For anyone trying to understand the complexity of the effects excess nutrients have on a watershed—or perhaps trying to explain those effects to others—this is an invaluable resource. It is available in printed or pdf form.
G. Fred Lee, a member of Stormwater’s editorial advisory board and president of G. Fred Lee & Associates in El Macero, CA, has pointed out an error in the information above. He says that although it’s a common misconception, even before they were phased out phosphates in detergent were not a major source of phosphorus in US water bodies. He has provided a link to a paper he co-authored on this issue:
G. F. Lee and R. A. Jones. 1986. “Detergent Phosphate Bans and Eutrophication.” Environ. Sci. Technol. 20(4):330-331.
The USGS report notes that nutrient sources have remained fairly stable since about 1980, and it lists the most common sources: application of commercial fertilizer accounts for the majority, followed by livestock manure and atmospheric deposition of nitrogen.