responsiveness summary to public comments - US Environmental ...

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EPA Response: During EPA’s public notice, the State provided EPA with a biological
assessment report on Hinkson Creek, dated December 18, 2002. EPA believes there is basis for
adding Hinkson Creek back to the list based on the following findings contained in the biological
assessment report: (a) Total Taxa and EPT (Ephemeroptera (Mayflies), Plecoptera (Stoneflies),
Trichoptera (Caddisflies) Taxa exhibited a sharp drop in the urbanized portion of Hinkson Creek;
(b) In the Spring of 2002, stoneflies were present in samples collected from the upstream two
stations, but absent at stations within the urbanized reach; (c) The Semi-quantitative Macroinvertebrate
Stream Bioassessment Project Procedure found that during the Fall of 2001 the
macroinvertebrate community of Hinkson Creek was partially sustaining in the upstream three
sample sites and fully sustaining at the remaining five downstream sites. During the Spring of
2002, this trend was reversed; the macroinvertebrate community at the upper two stations were
fully sustaining, whereas the downstream six stations were partially sustaining. Although the
study did not identify specific pollutant(s), the planned second phase of MDNR’s study will
answer that question.
EPA is noting for the record that during MDNR’s public notices of the draft 2002 Section
303(d) list, MDNR had proposed to divide the original 11-mile segment of Hinkson Creek that
was listed in 1998 into two classified segments (i.e., 6 miles-WBID 1007 and 5 miles-WBID
1008). The State’s public notice(s), prior to its final list submission to EPA, identified the 5mile
segment (WBID 1008) as an Addition to the list. The reduction of the original listed
segment (WBID 1007) from 11-miles to 6 miles was noted as a Change. However, it was the 5mile
segment (WBID 1008) which was proposed for delisting by MDNR in the State’s final
submission. The original 1998 listed segment (WBID 1007), albeit reduced to 6 miles, was not
accounted for in the State’s final submission. It may have been the State’s intention to delist the
entire 11-mile segment of Hinkson Creek regardless of this bifurcation. EPA is retaining the
originally listed 11-mile section of Hinkson Creek on the 2002 Missouri 303(d) list for an
“unspecified” pollutant based on information contained in MDNR’s Biological Assessment
Report of Hinkson Creek which indicates impairment of its aquatic life use designation.
With regard to public comments critical of listing for “unspecified” or “unknown”
pollutants, EPA regulations require states to identify all waters still requiring TMDLs where
standards are not met or are not expected to be met through the application of controls described
in 40 C.F.R. Section 130.7(b)(1). While the Act specifies that TMDLs shall be developed for
pollutants, Section 303(d)(1) simply requires that certain waters be listed. The regulations do not
exempt waters where the specific pollutant causing or expected to cause the exceedence of the
applicable water quality standard is not known. Where either EPA’s or MDNR’s evaluation of
data and/or information of the waterbody’s designated use, numeric criteria, or narrative criteria
for waterbodies, classified and unclassified, indicate impairment of the natural biological
community, then the waterbody should be included on the State’s 303(d) list. As such, listing
for “unknown” or “unspecified” pollutants is a valid listing until such time as a specific pollutant
or pollutants have been determined through additional monitoring and assessment before a
TMDL is actually developed.