Once a year, a group of tiny but valiant fathead minnows and freshwater fleas hazard illness and even death to put the output from the Quantico Advanced Wastewater Treatment Plant to the ultimate toxicity test, living in — and in the case of the minnows, breathing — the sewage plant’s effluent for days on end.

These unsung heroes risk their lives to ensure the safety of all life in the lower Potomac River. So far, the treatment plant’s staff has not let them down, and the product has been pure enough that the little creatures have emerged from the trial more or less unscathed.

The plant tests daily for about half a dozen pollutants, but the truest test of toxicity is whether its output harms river organisms. So, in accordance with the plant’s permit, an independent laboratory annually collects samples from the facility’s outfall into the Potomac and introduces the fleas and minnows into it.

There are streams in Northern Virginia that are too polluted to support populations of these sensitive species, but this year, they thrived and even multiplied in effluent from the plant that treats wastewater from the main side of Marine Corps base Quantico and the town of Quantico.

 “If there are other things in the water we don’t test for, you’ll see it in this test,” said Stacy Rosenquist, supervisor of the Environmental Compliance Section. “It’s kind of a holistic approach to testing whether we’re harming the environment.”

The samples were collected in October. They were diluted five times to mimic concentrations at the plant’s outfall, and the water fleas were placed in them for three days, while the minnows lived in the effluent for a week. On Nov. 1, the results came back. Survival rates were more than 100 percent, meaning the little animals not only survived but reproduced.

In years past, Rosenquist said, the lab has mistakenly tested undiluted sewage plant output, and even then, most of the little animals survived.

Tom Sperlazza, utility general foreman for the base, said this year’s results were especially remarkable because the plant has undergone constant renovations over the last year and a half.

“There’s hardly a feature there that’s part of the treatment process that hasn’t been refurbished,” Sperlazza said, noting that the digesters, equalization tank, ultraviolet lights, grit system and other major components have been upgraded  in the last 18 months.

“Even with the plant going through all this work and renovation, the staff has been able to maintain high-quality effluent into the bight,” Rosenquist said, referring to the portion of the Potomac River between the base and Chopawamsic Island.

She said freshwater fleas and fathead minnows are used in the test because they’re native to the region and highly sensitive to pollution. “They’re the perfect organisms to use to evaluate water toxicity,” Rosenquist said.

Sperlazza said work on the plant should be finished in about a year, right around the time another cohort of fleas and minnows bravely take the plunge.

— Writer: mdicicco@quanticosentryonline.com