- Published on Friday, 04 May 2012 22:26
- Written by Super User
RALEIGH, N.C. : April 27, 2012 - Officials with the N.C. Department of Environment and Natural Resources have developed a draft strategy to take additional steps to reduce the amount of mercury in North Carolina waterways and invite public comment on the proposal.
DENR’s divisions of Water and Air Quality will lead two public meetings next month to gather input on the department’s proposed statewide mercury management strategy for waterbodies. The first meeting is scheduled for May 14 from 12:30-2:30 p.m. at the Western Piedmont Council of Governments, 1880 2nd Ave. NW in Hickory. The second meeting is scheduled for May 23 from 1-3 p.m. at the Craven Cooperative Extension Building at 300 Industrial Drive in New Bern. DENR plans to present the draft strategy to the Environmental Management Commission in July.
Mercury occurs naturally in the environment, but human activity has increased the amount of mercury in the air, in soils and in surface waters. Worldwide, air emissions from fossil fuel combustion, mining and smelting and solid waste incineration represent the primary source of mercury later found in the water. Air-borne mercury can be directly deposited on a water body or be deposited on land and washed into rivers, lakes and streams in stormwater runoff. Humans are exposed to mercury primarily by consuming fish that contain methylmercury – an organic form of the metal that is found in lakes and rivers worldwide. In North Carolina, methylmercury has been found in fish caught in water bodies from the far western part of the state to the Lumber River basin and the lower Cape Fear River in the east. However, higher levels of mercury found in some large predator fish - such as largemouth bass, walleye, chain pickerel and bowfin - have prompted the Department of Health and Human Services to issue a statewide mercury fish consumption advisory for children under 15 and for women who may be pregnant or may become pregnant.
The federal Clean Water Act requires the state to develop a total maximum daily load, or TMDL, for a pollutant that causes water quality impairment in a water body within the state. Development of the mercury TMDL is the first step toward reducing in-state contributions to mercury impairment in state waters. The TMDL describes the causes of the mercury impairment and the amount of reduction in mercury loading that would be required to ensure that the affected water bodies meet water quality standards. In this case, the TMDL document estimates that 98 percent of the mercury loading in water bodies comes from air emissions (mostly from out-of-state sources) rather than wastewater discharges, so the direct impact on water quality permit holders in the state will be minimal. The TMDL will be subject to approval by the U.S. Environmental Protection Agency.
The second part of the plan is a water quality permitting strategy for those entities with National Pollutant Discharge Elimination System (NPDES) wastewater permits based on the TMDL.
Since wastewater dischargers represent only 2 percent of the mercury loading, the permitting strategy does not place significant new demands on municipal and industrial dischargers; instead, the water quality permitting strategy focuses on ensuring that those permitted discharges do not create localized mercury problems.
Air emissions will not be subject to the water quality permitting strategy. North Carolina’s coal-fired power plants have substantially reduced their air emissions of mercury as a result of controls required under the 2002 Clean Smokestacks Act.
Further reductions from utilities and other industrial sources are expected under new EPA requirements that limit toxic air emissions from electric power plants and industrial boilers. In combination, these actions are expected to reduce total mercury emissions by 70 percent and deposition-prone mercury emissions by 81 percent in North Carolina.
To build on these significant steps, the Division of Air Quality has developed a list of options for achieving additional reductions in mercury air emissions that will be presented at the public meetings in May. The public is invited to comment on these options or suggest additional ones. The options include:
• Filing a legal petition aimed at seeking reductions in mercury air emissions from sources outside North Carolina (in-state sources are estimated to cover only 16 percent of mercury emissions);
• Establishing a statewide emissions reduction credit program for mercury reductions;
• Setting a cap on statewide mercury emissions with a cap-and-trade program for existing and new facilities to allow for future growth;
• Establishing case-by-case evaluations of control technologies at any new or modified existing facilities that would result in increased mercury emissions; and
• Creating a mercury mitigation fund that would provide grants for projects with low to zero mercury emissions.