Business, fish advocates at odds over NC's strict limits on silver in wastewater

State lawmakers met Tuesday at the North Carolina Zoo to discuss whether water regulations should be loosened to help businesses. It's a change that could prove dangerous to aquatic life.

North Carolina has tightest standard in the country to keep silver out of surface waters and streams.

Many industries use silver and discharge trace amounts of it in their wastewater. As the state grows, city wastewater treatment systems say they can’t get the silver down to the level required in the treated water they release.

On Tuesday, AquaLaw co-founder Paul Calamita told state lawmakers that North Carolina law is too strict and research shows the limits are not necessary. He said most states don’t even have a silver standard.

“We do not want to have to impose restrictions on the businesses to discharge our wastewater plant, forcing them to reduce chronic silver when there's no toxicity issue,” he said.

State Rep. Pricey Harrison, D- Guilford County, couldn’t believe it.

“It's got this toxicity level that we are seeing in aquatic species, and we know it's a problem and we're just talking about eliminating the standard,” Harrison said.

Calamita said his group may ask lawmakers this summer to loosen the regulations on silver in surface waters. Environmental regulators say they’re working on a compromise, but they don’t want to lessen water quality.

Silver is toxic to aquatic life, but no so much to people.

The North Carolina Water Quality Association, which claims to represent low-income water users, is pushing to relax the standards saying they're overly strict. The North Carolina Department of Environmental Quality (DEQ) is trying to find a way not to relax them.

According to presentation materials provided by the DEQ, eight in 10 species that are most sensitive to silver as evaluated by the Environmental Protection Agency (EPA) are found in North Carolina surface waters:

• Daphnia (most sensitive)
• Fathead minnow (second-most sensitive)
• Bluegill
• Rainbow trout

DEQ uses two standards to protect aquatic life against toxins:

• Acute standards: Protect organisms from short-term exposures that may result in death
• Chronic standards: Protect organisms from long-term exposures that may impact growth, reproduction and behavior

The Environmental Management Commission (EMC) has oversight of North Carolina’s federal environment programs such as the Clean Water Act, which requires the state to adopt standards to protect designated uses, such as aquatic life. The EMC adopted its current chronic silver standard in 1989 to address discharge of silver from industrial facilities.

In March, the EMC heard a petition from the North Carolina Water Quality Association with a request to remove the standard for silver. The EMC denied the petition.

State lawmakers could take up the issue again when they convene on May 18.