responsiveness summary to public comments - US Environmental ...

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invertebrate protocols 3 can be expressed qualitatively as the number of taxa. EPA reviewed a
number of sources in selecting the tolerance values that were utilized in determining impairment
or non-impairment. These sources were listed in Enclosure 1 to EPA’s April 29, 2003 decision
letter to Missouri regarding their 303(d) list. Not all authors are in agreement on tolerance
values. However, EPA reconciled differences by seeking the advice of an unbiased expert,
Leonard C. Ferrington, Jr., PhD, Department of Entomology, University of Minnesota, and
former Associate Director, Kansas Biological Survey, on the appropriateness of the tolerance
values.
2. EPA disagrees with the comment that the visual/benthic surveys do not indicate
impairment. In general, impairment was ascribed to waters where either actual chemical data or
combination or cumulation of factors such as “large amounts of algae” (which EPA believes
carries considerable weight in visually determining impairment), along with elevated
conductance and turbidity, and “reduced aquatic diversity” indicate impairment. With regard to a
commenter’s comparison of McCarty Creek (WBID 13378), East Honey Creek (WBID 555), and
Sandy Creek (WBID 652), to further support their argument that the visual/benthic surveys do
not indicate impairment, EPA has the following response:
a. McCarty Creek (WBID 1338) - No Visual/Benthic survey form was provided
to EPA. However, chemical monitoring data collected by MDNR, and included in their revised
“Monitoring Report on the 26 Waters”, indicated compliance with Missouri’s water quality
standards. This coincides with the summary of aquatic life present in the stream which appears
to indicate good overall stream health. Accordingly, EPA did not add McCarty Creek to the
Missouri’s 303(d) list.
b. East Honey Creek (WBID 555) - As presented in Enclosure 1 to EPA’s April
29, 2003 decision letter to Missouri regarding their 303(d) list, a combination of factors led to
EPA’s conclusion that this waterbody was impaired. For instance, the State’s “Monitoring
Report on 26 Waters” describe specific conductance was slightly high when compared to streams
in the same region and with similar drainage and discharge. Furthermore, minor growth of
epilithic, filamentous algae was noted by the state and the water was slightly turbid. The state
has concluded in its comparative notes that the slightly elevated conductivity levels and minor
algal growth suggest that nutrients are entering the stream. However, EPA found during it
review of public comments that it had overlooked a visual/benthic survey form which was
available during its original review of the State’s 303(d) list. EPA, therefore, calculated the
average tolerance value of taxa report at the monitoring site for this waterbody. The average
tolerance value of the taxa reported at the monitoring site for this waterbody indicates a CTI
value of 6.3 which falls below the 6.5 cut-off value. Consequently, EPA is removing East Honey
Creek from the Missouri 2002 Section 303(d) list.
3 U.S. EPA. July 1999. Rapid Bioassessment Protocols for Use in Wadeable Streams and Rivers - Periphyton, Benthic,
macroinvertebrates, andFish. 2 nd Edition. EPA 841-B-99-002.