The Revised Charleston Harbor Dissolved Oxygen TMDL

The Clean Water Act (CWA) is built upon a foundation of public participation in water quality protection. Making use of the CWA’s public participation provisions and other laws, like the Freedom of Information Act, is a big part of our work here at Charleston Waterkeeper. This past week we received a response from DHEC to comments we submitted late last year regarding the Revised Charleston Harbor Dissolved Oxygen TMDL. So what’s a TMDL? Why did we comment on it? Why are we writing about it now? Read on.

A Quick History Lesson

In the 1990s scientists discovered the Charleston Harbor estuary frequently experienced low levels of dissolved oxygen (DO). The low DO levels meant that much of the estuary failed to meet state water quality standards for dissolved oxygen. Low levels of DO threatened the health of fish and other aquatic species. Research revealed the problem was due to both natural conditions and point source discharges from NPDES permit holders.

This triggered DHEC’s obligation under the Clean Water Act to develop a DO total maximum daily load, or TMDL for short. A TMDL is a plan to cap the total discharge of dissolved oxygen demanding pollutants to help the estuary meet its water quality standard for DO. The cap is then divided among all sources of oxygen demanding pollutants.

To set the cap, DHEC and scientists attempted to develop a computer model that incorporated the Ashley, Cooper, and Wando Rivers and the Charleston Harbor. However, the computers available at the time were not powerful enough to run the model. DHEC ultimately developed two TMDLs, one for the Ashley River and another for the Cooper and Wando Rivers and the Charleston Harbor.

Another Acronym Gets Involved

The TMDLs required NPDES permit holders to achieve a 60% reduction in discharges of oxygen demanding pollutants. DHEC and permit holders agreed to implement the reductions in two phases. The first phase was implemented in most permits by 2003 (a few permit holders challenged implementation in court). Shortly afterward, the Cooper River Water Users Association, a coalition of NPDES permit holders working through the Berkeley, Charleston, Dorchester Council of Governments (BCDCOG), offered to fund development of a “3D” model that would incorporate the Ashley, Cooper, and Wando Rivers and the Charleston Harbor.

DHEC agreed to work with the BCDCOG and the Cooper River Water Users Association on development of a 3D water quality model to inform implementation of the second phase of reductions. Two environmental engineering firms, Tetra Tech and Jordan, Jones, and Goulding, completed the 3D model and delivered it to DHEC in 2008. Afterwards, DHEC began development of a revised TMDL, combining and updating the Ashley River TMDL and the Cooper and Wando Rivers and Charleston Harbor TMDL.

In October 2012, DHEC issued public notice of its revision and published a draft of the revised TMDL for public comment. Charleston Waterkeeper requested an extension of the 30 day comment period and filed a Freedom of Information Act request in order to review the documentation contained in DHEC’s files regarding development of the revised TMDL.

After reviewing the draft revised TMDL, 3D modeling report, and DHEC’s TMDL file we developed several concerns regarding the provisions for public participation and how the TMDL accounted for stormwater inputs. We submitted our comments to DHEC in late December 2012. The South Carolina Department of Natural Resources and the EPA also submitted comments.

TMDLs are Complicated

This lengthy narrative highlights the simple fact that TMDL development is difficult. Unfortunately, this also presents a significant barrier to public participation. For instance, the TMDL document itself is forty-three pages long. DHEC’s TMDL file contains thousands of pages of technical reports, scientific studies, correspondence, and notes. The 3D modeling report requires an environmental engineering background and experience with water quality modeling to fully understand.

That’s why the work of groups like Charleston Waterkeeper is so important. Our work lowers the barrier to public participation. We were able to use the power of the law to review DHEC’s files, extend the public comment period, and devote resources to reviewing the TMDL and its supporting materials to ensure the public’s right to clean water is adequately protected. Without this work the public would lack a voice in the TMDL process.

DHEC takes public comments seriously and considers and responds to each comment. In response to our comments DHEC added language to the TMDL clarifying how stormwater inputs were accounted for in the TMDL. DHEC also added an explicit statement outlining how public notice and comment are handled when the revised TMDL is implemented and reallocated in the future. Charleston Waterkeeper is proud to play a role in development of the revised TMDL. We believe our water quality is best protected when DHEC, permit holders, and the public are actively engaged in the TMDL process.

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