Main Menu

EPA Approves Majority of Kentucky Division of Water’s Triennial Review Water Quality Standards


Over the past year, we have reported on progress with respect to the Kentucky Division of Water’s (DOW) development of amended regulations as part of its Triennial Review of Water Quality Standards.  The amended regulations at 401 KAR 10:001, 10:026, and 10:031 became effective as a matter of state law in the Spring of 2013.  The Energy and Environment Cabinet (Cabinet) transmitted the amended regulations to EPA for review and approval pursuant to Section 303(c) of the Clean Water Act on May 23, 2013.  By letter dated November 15, 2013, EPA approved all of the proposed amendments except for a revised acute water quality aquatic life criterion for selenium.

The Triennial Review amendments that were submitted to EPA for approval contain several important provisions for municipal and industrial wastewater dischargers.  First, DOW adopted revised water quality aquatic life criteria for selenium, which were very controversial and received extensive comments in opposition during the regulatory review process from environmental interest groups.  Kentucky’s existing acute and chronic water quality criteria for selenium were adopted in 1990 and were considered not scientifically sound or defensible.  DOW adopted amended chronic and acute water quality criteria for selenium based upon more current studies and data, including those cited in EPA’s 2004 draft selenium criteria document.  DOW adopted a proposed acute criterion for warm water aquatic habitat for selenium of 258 ug/L, with an alternate acute standard based upon a formula where the concentration of sulfate is less than 44 ug/L.  The adopted water quality chronic criteria for selenium are 8.6 ug/g and 19.2 ug/g in whole fish tissue and fish egg/ovary tissue, respectively.  These proposed values were derived by DOW based on species native or naturalized to Kentucky waters.

In approving the chronic selenium criteria, EPA found the standards were scientifically defensible and protective of the designated use of warm water aquatic habitat in Kentucky’s waterbodies.  Although EPA was concerned regarding certain implementation issues, Kentucky affirmed in a letter to EPA that in the event sufficient fish tissue could not be obtained in a stream for testing, the permit holder would be deemed to be in noncompliance with its KPDES Permit if it exceeded the chronic water column trigger level of 5.0 ug/L of selenium.  The trigger level is used to determine if fish flesh testing is required.

With respect to the adopted acute criterion, EPA found that existing science indicates that short term impact to aquatic life can result from low level exposure to selenium in the water column.  EPA found that the acute criterion that DOW adopted does not provide adequate short term protection because it is based on water-only exposure with no associated aquatic life dietary exposure.  As a result of EPA’s disapproval of the acute criterion, EPA explained DOW’s previous acute water quality criterion of 20 ug/L remains in effect for all Clean Water Act purposes.  EPA’s November 15, 2013 letter notes that to resolve the disapproval, Kentucky must develop and adopt an acute criterion that protects for short term exposure and is derived from the approved chronic fish tissue based criteria.  EPA stated it was willing to work with DOW on the development of such a criterion.

The second significant amended water quality standard that was approved by EPA relates to the narrative nutrient standard.  Kentucky’s prior narrative nutrient standard for protection of aquatic life provided that in “surface waters where eutrophication problems may exist, [nutrients] shall be limited in accordance with: (1) the scope of the problem; (2) the geography of the affected area; and (3) relative contributions from existing and proposed sources.”  (Emphasis added.)  DOW revised the narrative nutrient standard to clarify it consistent with its long-term interpretation of requiring effluent limitations on the discharge of nutrients (e.g., phosphorus and nitrogen) only where the discharge would cause or contribute to a eutrophication problem.  The reference to situations where a eutrophication problem “may exist” was deleted from the regulation.  DOW also clarified the definition of “eutrophication” at 401 KAR 10:001 Section 1(30) as the enrichment of surface water with nutrients nitrogen and phosphorus that results in adverse effects on water chemistry and the indigenous aquatic community.  Accordingly, consistent with the application of other water quality criteria for protection of aquatic life, nutrient limitations are required where the discharge would cause or contribute to adverse effects on indigenous aquatic life.  In approving DOW’s revised narrative criterion, EPA found the standard to be adequate to ensure the protection of the designated use and precludes “elevation of nutrients such that the nutrients result in a problematic eutrophic condition.”

Finally, EPA also approved DOW’s clarification of the dissolved oxygen standard that applies to the main stem of the Ohio River at 401 KAR 10:031 Section 9(2).  Specifically, DOW clarified that the dissolved oxygen standards set forth in the regulation are “instream” concentrations and do not apply at the end-of-pipe.  This clarification is intended to ensure that the standard is construed consistent with the Ohio River Valley Water Sanitation Compact (ORSANCO) dissolved oxygen standard and the long-standing application of the dissolved oxygen standard by EPA and DOW.  In approving the standard, EPA acknowledged that the revised standard clarifies that the dissolved oxygen criteria applies instream and not at the end-of-pipe.

To view a complete PDF of the September/October 2013 issue of the Environmental Letter, click HERE.

Back to Page