Skip to main content

Regional Approach for Mercury TMDLs: Quantifying Atmospheric Deposition for Coastal Louisiana

Buy Article:

$9.50 plus tax (Refund Policy)

Or sign up for a free trial

Despite growing national interest in pursuing alternatives to total maximum daily loads (TMDL) for addressing fish consumption advisories for mercury, the U.S. Environmental Protection Agency (USEPA) Region 6 was compelled by a settlement agreement to prepare TMDLs for coastal bays and Gulf waters of the entire Louisiana coastline. A comprehensive paper summarizing the technical approach is not available for inclusion in the WEF TMDL 2005 Conference Proceedings because the TMDL Report was not finalized to the level required by USEPA Region 6. However, the presentation will highlight the key elements of the TMDL technical approach.

More than 44 states list waterbodies as impaired as a result of mercury levels in fish tissue concentrations high enough to warrant consumption advisories. To adequately address mercury sources potentially contributing to the fish consumption advisory for king mackerel in Louisiana, a basin-scale assessment approach was deemed necessary to evaluate the Coastal Bays and Gulf Waters and their contributing watersheds. Given the ubiquitous distribution of mercury and the large geographic area considered in this assessment, a regional rather than a waterbody-specific approach was used to develop the TMDLs. Recognizing the need to conduct a more thorough identification and quantification of mercury loading from point and nonpoint sources, Region 6 relied on Parsons for technical support to link recent advancements in modeling atmospheric deposition using the Regional Modeling System for Aerosols and Deposition (REMSAD) with the Pollutant Load Application (PLOAD) of the Better Assessment Science Integrating Point and Nonpoint Sources (BASINS) watershed loading model. It is well-known that a major source of mercury deposition to many of our nation's waters is from the atmosphere. To support development of these TMDLs for coastal Louisiana, REMSAD atmospheric deposition modeling was used to segregate wet and dry deposition into local, regional, and global air sources by calculating wet and dry loading estimates to both terrestrial and aquatic surfaces. Because of the large surface water area in southern Louisiana, this was a critical step in refining the quantification of mercury loading into receiving waters.

Since more than 90 percent of mercury in receiving waters is attributable to air emissions, special emphasis was placed on distributing the burden of reducing mercury loading on facilities with mercury air emissions and not just on municipal and industrial wastewater dischargers. Alternative approaches were identified to provide the State with flexibility in its permitting program so mercury limitations for NPDES dischargers could be established or lowered only when warranted. This approach also addressed any potential localized impact of this persistent bioaccumulative pollutant by a point source discharger. While the fate and transport of mercury through the aquatic environment is very complex and not completely understood, certain simplifying assumptions about mercury loading were made so required reductions could be identified and a TMDL determined.

This technical presentation summarizes the data compilation, assessment results, and policy decisions associated with developing draft mercury TMDLs for the fish consumption advisory placed on king mackerel (Scomberomorus cavalla) in the coastal bays and Gulf waters of Louisiana. Data compilation and assessment results occurred between September 2003 and April 2005. The technical presentation provides an overview of the various issues and methods considered and utilized in developing TMDLs for mercury using a regional or basins-cale approach. While information provided in the presentation is derived primarily from development of mercury TMDLs in coastal Louisiana, a number of questions and issues that apply to a 303(d)-listed water body anywhere in the U.S. with a fish consumption advisory is addressed.
No Reference information available - sign in for access.
No Citation information available - sign in for access.
No Supplementary Data.
No Article Media
No Metrics

Document Type: Research Article

Publication date: 2005-01-01

More about this publication?
  • Proceedings of the Water Environment Federation is an archive of papers published in the proceedings of the annual Water Environment Federation® Technical Exhibition and Conference (WEFTEC® ) and specialty conferences held since the year 2000. These proceedings are not peer reviewed.

    A subscription to the Proceedings of the Water Environment Federation includes access to most papers presented at the annual WEF Technical Exhibition and Conference (WEFTEC) and other conferences held since 2000. Subscription access begins 12 months after the event and is valid for 12 months from month of purchase. A subscription to the Proceedings of the Water Environment Federation is included in Water Environment Federation (WEF) membership.

    WEF Members: Sign in (right panel) with your IngentaConnect user name and password to receive complimentary access. Access begins 12 months after the conference or event
  • Subscribe to this Title
  • Membership Information
  • About WEF Proceedings
  • WEFTEC Conference Information
  • Learn about the many other WEF member benefits and join today
  • Ingenta Connect is not responsible for the content or availability of external websites
  • Access Key
  • Free content
  • Partial Free content
  • New content
  • Open access content
  • Partial Open access content
  • Subscribed content
  • Partial Subscribed content
  • Free trial content
Cookie Policy
X
Cookie Policy
Ingenta Connect website makes use of cookies so as to keep track of data that you have filled in. I am Happy with this Find out more