Water Quality Management - River Dynamics and Integrated River Management - page 579

Rankin (1989) examined relations between the QHEI and the Index of Biological Integrity (IBI)
(Section 10.4.2) in order to develop a procedure for relating stream potential to habitat quality that would
provide some insight into how habitat might affect biological expectations in a given water body. The
goal of his study was to provide guidance on the specification of aquatic life uses (i.e. potential aquatic
ecological community) for water bodies that were impaired by pollution impacts. Rankin (1989, p. 2)
noted that the procedure developed “needed to be useful enough to separate the relative effects of habitat
versus water quality on fish community structure or at a minimum determine the baseline community that
could be expected in a particular habitat.” To develop the relations between QHEI and its subcomponent
metrics and life uses Rankin (1989) considered data from a large number and wide variety of streams in
Ohio including:
(1) streams that represent sites minimally impacted by chemical water quality or habitat,
(2) streams that contain areas that have relatively un-impacted water quality but have documented
habitat impacts (“modified” reference sites), and
(3) within stream basins where the State of Ohio had used the QHEI in some water quality management
decision.
In total, Rankin (1989) evaluated conditions for 471 reference sites throughout the State of Ohio.
Rankin (1989) found that for QHEI values less than 46, 72.5% of the waters evaluated had IBI values
falling in the poor range, 23.5% falling in the fair range, and only 4% falling in the good range. When
summarizing results such as these with respect to the relation between habitat, fish communities, and
water-quality management Rankin (1989, p. 52) offered the following warning:
“It makes little sense to protect the biota by multimillion dollar improvements to a point source discharge
while important biological uses are impaired by habitat modifications for reasons such as flood control,
construction activities, and waterway improvements.”
Hence, for cases where the QHEI is less than 46 a lower use standard (Modified Warmwater Stream),
which must meet a lower DO concentration standard, is designated. Similarly, Rankin (1989) found that
for QHEI values greater than 60, 26% of the waters evaluated had IBI values falling in the exceptional
range, 54% falling in the good range, 17% falling in the fair range, and only 3% falling in the poor range.
Thus, waters with QHEI values greater than 60 are designated Warmwater Streams for which the full
CWA goals can be obtained. For QHEI values in the range 46 to 60, Rankin (1989) found 5% of the
waters evaluated had IBI values falling in the exceptional range, 25% falling in the good range, 41%
falling in the fair range, and 29% falling in the poor range. Thus, in this range waters are designated
Warmwater Streams or Modified Warmwater Streams depending on the values of the individual QHEI
component metrics. Table 9.9 indicates the key factors that determine whether a river is a Warmwater
Stream or Modified Warmwater Stream. Finally, rivers with very low QHEI values less than 30 or 32 may
be designated as Limited Resource Waters.
In the State of Ohio the DO criteria for Modified Warmwater Streams is a daily minimum of 3.0 mg/L
and a daily average of 4.0 mg/L, and the minimum reduces to 2.5 mg/L in the Huron/Erie Lake Plain
Ecoregion (Ohio rule 3745-1-07). Whereas for Limited Resources Waters the criterion for the daily
minimum is 2.0 mg/L with a daily average of 3.0 mg/L (Ohio rule 3745-1-07). Such ecologically justified
standards, tailored to the ecological conditions of a State or region, should be considered in all areas as a
way to logically achieve the goals of the CWA.
9.2.4.3 Dissolved Oxygen Remediation
The best solution to the pollution problem is prevention—not to produce and discharge pollutants in the
first place and to manage lands so that they do not result in degradation of receiving waters and other
resources (Novotny, 2003, p. 50). Thus, the most effective means to improve DO concentrations in a river