OPINION: Plant, not farmers, linked to phosphorus spike

US - Alex Avery, a longtime Bay Journal reader, couldn’t believe what he was reading in the October issue when he saw that phosphorus levels in the North Folk of the Shenandoah River had increased nearly 300 percent since 1985, or that the poultry industry could be responsible.

The figure appeared in a cover story about the 20-year-old tidal river monitoring program in the Bay watershed. The article reported that nutrient and sediment concentrations in most rivers, when adjusted to compensate for the influence of river flow, were below their 1985 levels. The article also reported that decreases in many of those rivers had halted, and in the past decade had begun trending upward.

One of those rivers was the Potomac. where phosphorus concentrations, according to the U.S. Geological Survey, which oversees the monitoring network, are now higher than they were in 1985. The article indicated that much of that increase appeared to stem from the North Fork of the Shenandoah River, heart of Virginia’s poultry industry, where monitoring showed phosphorus concentrations had increased dramatically since the late 1990s.

Avery, director of research for Hudson Institute’s Center for Global Food Research, disputed whether there was an increase, and could not believe that the area’s poultry farmers had caused nutrient problems in the river. He challenged both the article, and the USGS data. He, along with USGS scientist Jeff Raffensperger, both dug through figures to get to the bottom of the story.

Their conclusion: Phosphorus levels in the river had indeed spiked in recent years. The primary reason appeared to be a large increase in discharges from a combined poultry processing plant and animal rendering plant (which handled a wide array of animal carcasses) in the area.

That facility was recently upgraded, though, and phosphorus concentrations appear to have dropped sharply in the river since 2002-03. That drop is not fully reflected in the USGS figures because they are a long-term trend analysis and, of course, a single year of data does not yet constitute a long-term trend.

Source: bayjournal.com
calendar icon 31 October 2005
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