Something Fishy about the Shenandoah River
Arsenic from Poultry Farms Is One of Several Potential Causes for Shenandoah Fish Kills
The way Richard Morris sees it, if poultry litter was bad for fish, his farm pond would be in trouble. It’s fed only by drainage off his corn fields, which, like many Shenandoah Valley farms, he fertilizes with litter from his poultry houses. But the pond is thriving; Morris’ grandson pulls 20-inch bass out of it as quickly as he can cast his line.
Bass in the Shenandoah River, only about a mile west of Morris’ farm, have recently fared much more poorly, however. Fish kills have struck both branches of the river each spring since 2004, killing an estimated 80 percent of adult smallmouth bass and a few other species. Four years later, and despite the best efforts of an expert-laden “fish kill task force,” there are few good answers to the many whys: Why the Shenandoah? Why now? Why just adults from a few species?
The prevalence of poultry farming in the Valley jumps out as one unique watershed characteristic that may point to the cause. But that may be too simple an answer for these fish kills. According to the fish kill task force, it’s likely the combined effect of several environmental stressors: nutrification, pathogens, runoff, and numerous different contaminants weaken and eventually kill certain fish.
That’s not to say that the hundreds of thousands of tons of litter produced each year in the Valley’s roughly 900 poultry farms—most of which is then spread as fertilizer on nearby fields—have been ruled out. One hypothesized fish kill cause involves the introduction of arsenic into the Shenandoah watershed through the use of poultry litter as fertilizer. The poultry feed additive Roxarsone has attracted growing scrutiny nationwide as an environmental health concern. Roxarsone, or 3-nitro-4-hydroxyphenylarsonic acid, has been used for decades to control intestinal parasites and promote growth in poultry. It contains arsenic, though bound up in a relatively harmless form. Once Roxarsone finds its way through the bird and into the litter, however, bacteria can quickly break it down and release inorganic arsenic, a known human carcinogen, and an immune system suppressor in fish.
Recent testing by the Virginia Department of Conservation and Recreation (DCR) detected arsenic ranging from 0.3 parts per million to 30.3 parts per million, probably because the six major poultry companies operating locally don’t all use Roxarsone the same way, if at all. Tyson, for example, discontinued Roxarsone use in 2004 in response to growing national concern over potential human health impacts. Cargill—the company for whom Morris raises turkeys—hasn’t used Roxarsone locally for a number of years.
Nevertheless, the DCR testing found an average arsenic concentration of 11.7 parts per million, noticeably higher than horse, beef, and dairy cattle manure samples also tested. Because inorganic arsenic is water soluble, arsenic in poultry litter spread on fields can eventually be washed into the river and contribute to the fish kills.
Arsenic in excess of the Department of Environmental Quality’s screening value showed up in 19 percent of Shenandoah River fish tissue samples tested in 2005. The finding doesn’t necessarily mean arsenic caused the fish kills; 2005 tissue samples from the nearby York and Holston watersheds, neither of which have experienced Shenandoah-like kills, exceeded the arsenic screening value by 56 percent and 36 percent, respectively.
The poultry industry has reacted with skepticism to the idea that poultry litter or Roxarsone specifically has anything to do with the fish kills. Hobey Bauhan, president of the Virginia Poultry Federation, an industry advocacy group, acknowledges the DCR testing showing elevated arsenic levels in litter. But, he points out, the average concentration of 11.7 parts per million falls well short of the U.S. Environmental Protection Agency’s arsenic standard for land-applied biosolids from sewage treatment plants, set at 75 parts per million.
For that matter, arsenic also shows up in various forms in pesticides historically used in the area, and it also occurs naturally in the soil (locally, only in small amounts, thanks to underlying geology). Even if some level of fish kill blame eventually falls on arsenic, poultry litter couldn’t be the lone culprit, says Bauhan, whose organization has donated $20,000 to fund fish kill investigations.
“If someone proves it’s poultry litter, which I doubt will happen, then [poultry] growers and [companies] will do everything they can to stop it,” says Morris.
Nevertheless, testing by state regulatory agencies—and the majority of scientific literature on the subject—strongly suggest that Roxarsone use in the Valley means more inorganic arsenic at large in the Valley. For Jeff Kelble, Shenandoah Riverkeeper for the environmental advocacy group Potomac Riverkeeper, that’s reason enough for action.
“There’s a business that’s electing to continue introducing a known carcinogen and toxic substance onto the land, and then into the water,” he says. “That’s a problem.”
If anything, Kelble says, the topic deserves further study, and the poultry industry should abandon Roxarsone altogether. DEQ is trying to find a middle ground.
“I don’t see [arsenic] as our sole focus,” says Don Kain, water compliance manager for the DEQ and a co-chair of the fish kill task force. Dr. Vicki Blazer, a U.S. Geological Survey fish pathologist, and Dr. Greg Garman, a Virginia Commonwealth University biology professor, echo Kain’s comments, emphasizing that arsenic remains just one of several potential causes, which include pesticides, herbicides, endocrine-disrupting hormones, pH swings, and unknown pathogens.
Roxarsone-derived arsenic raises numerous yet-unanswered questions, among the biggest: Why doesn’t it also affect streams on the Delmarva Peninsula, or in Georgia, or Arkansas, or the other bright centers of the poultry universe?
In the meantime, bloated fish continue to float along the Shenandoah. The river is suffering from a thousand vague cuts, and there are good reasons against bandaging any single one. But doing nothing won’t stop the bleeding.