In March 2014, the Ohio River Valley Water Sanitation Commission (ORSANCO) announced that it was accepting public comments, technical scientific studies, and data through May 9, 2014, to assist in a review and update of its Pollution Control Standards for discharges to the Ohio River. ORSANCO identified an initial set of issues to be considered and addressed in the Triennial Review process. Several of the water quality standard issues that were identified are of significant interest to industrial and municipal sources discharging wastewater to the Ohio River. Because ORSANCO is an interstate compact, its Pollution Control Standards apply to discharges to the main stem of the Ohio River in addition to any more stringent state water quality standards.

A key water quality criterion identified for review is ORSANCO’s total mercury criterion of 0.012 µg/l (12 parts per trillion). ORSANCO’s 12 parts per trillion (ppt) criterion is considerably more stringent than the mercury water quality criterion adopted by several states that border the Ohio River, including Kentucky. Indiana has already adopted the 0.012 µg/l standard for mercury. ORSANCO’s criterion was derived from the same methylmercury fish tissue criterion of 0.3 mg/kg that formed the basis of many of the state standards. Therefore, ORSANCO utilized a more stringent translator to derive its water quality criterion.

A related issue is ORSANCO’s scheduled prohibition on mixing zones for bioaccumulative chemicals of concern (BCCs), which was modeled on EPA’s rules for the Great Lakes Initiative. ORSANCO noted on its website that the BCC prohibition under the Great Lakes Initiative was driven by the long retention times of the Great Lakes and the potential for mixing zones to create BCC hot spots. The same concerns may not exist with a flow through river system such as the Ohio River.

ORSANCO may also reevaluate other water quality criteria, including the existing total dissolved solids criterion, the temperature criterion of 110° F to protect human health during recreational use of the river, and the E. coli water quality criteria. ORSANCO is also considering whether it should begin development of numeric nutrient criteria for phosphorus and nitrogen.

ORSANCO will consider all comments submitted by the May 9, 2014, deadline. ORSANCO will consult with member states through its technical workgroups and committees in determining whether to revise its Pollution Control Standards. There will be another opportunity for public review and comment on proposed revisions, which will likely garner substantial public comment from industries, municipalities, and environmental interest groups. Final revisions to the Pollution Control Standards will likely be issued in 2015.