Carlyle Lake Final Plan.pdf - Fayette County Soil & Water ...

Among the twelve tributary streams resampled in 1997, conditions appeared to be slightly better,
on average, than in the Kaskaskia River proper. Overall mean AIBI score increased slightly (39.2
to 41.0) even though mean species richness declined (25.4 to 20.3) between 1983 and 1997. The
latter may have been largely attributable to changes in sampling methods, as the electric seine
was not as efficient as rotenone. The AIBI scoring system accounts, in part, for different methods
and also considers factors other than species richness. Therefore, while an increase in species
generally increases the AIBI score, this is not an absolute rule and was not the case here.
Some of the most degraded communities appeared in streams draining directly into Carlyle Lake
from the east. East Fork Kaskaskia River and its tributary, North Fork, maintained a “D” rating
(“Limited Aquatic Resource”) in its lowermost segment while East Fork upgraded slightly (from
“D” to “C” or “Moderate”) despite low species diversity. According to IEPA’s Illinois Water
Quality Report 1994 – 1995, these streams are impaired by siltation, nutrients and oxygendemanding
materials from nonpoint agricultural sources. A third stream, Wolf Creek, slipped
from “C” to “D”; oil field pollution may be a causative factor.
Conversely, the highest degree of biotic integrity in 1997 was displayed by Ramsey Creek and
Hurricane Creek. Each stream yielded a high number of species (29) and yielded AIBI’s of 49 and
51, respectively. This retains lower Ramsey Creek in the “A” category (“Unique Aquatic
Resource”); a designation carried by only 5% of Illinois’ rated stream miles. Meanwhile, the
lower most half of Hurricane Creek was upgraded from “C” to “B” (“Highly Valued Aquatic
Resource”) to reflect its elevated biological richness. Reasons for the improvement are unclear;
both streams exhibited high quality habitat typified by diverse pool/riffle/run sequences and
significant proportions of coarse substrate materials (i.e. gravel, cobble and boulder). While no
state threatened and endangered species were collected, each stream supported darters and other
fishes considered “intolerant” of environmental stress.
Elsewhere, tributary streams appeared in good shape with five streams (Big, Becks, Mitchell,
Richland, and Robinson Creeks) maintaining the “B” ratings (“Highly Valued Aquatic
Resource”) observed in 1983. Opossum Creek, a tributary of Becks, maintained its “C” status
from before. From a biotic integrity standpoint, streams of the middle Kaskaskia watershed
appear superior to those of the lower Kaskaskia basin (below Carlyle Lake) as reflected by a 1996
survey. While the entire Kaskaskia watershed is agricultural in nature, the section below Carlyle
is typified by somewhat flatter topography (and thus less diverse stream habitat), increasing
urbanization and locally intense livestock operations.
Resource management options might vary between “sub-basins” of the Carlyle Lake Watershed.
Due to the degraded nature of the East Fork/North Fork system (and its proximity to the lake
itself), the most intensive rehabilative measures may be exerted here. Riparian buffer strips,
upland sediment treatment, and pesticide/nutrient management may, in time, reverse or lessen
the severe agricultural impacts observed here. At the other extreme, protection of existing
resources, through voluntary conservation easements or similar measures, may allow Ramsey
Creek to maintain its presently high level of biotic integrity. Perhaps a combination of
remediation and protection tools could be employed in other parts of the watershed based upon
local resource conditions and the willingness of landowners.
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