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The photo on the left shows Milltown Dam in 1989.
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Blue River below Milltown Dam was visited on the following dates: September 25, 27, October 9 and 16. On September 25, we studied water chemistry and estimated discharge. On September 27, we performed RBPs. On October 9, we collected water for nitrate and phosphate testing. In addition, we collected 100 ml whirlpacks for fecal coliform bacteria testing. The river had high discharge at this time. On October 16, we collected water for water chemistry tests performed in the laboratory at IUS. The river was flooding at the time. The sites description below is based on September 25 data.
Blue River field site at Milltown dam (permanent sampling Site 7) was visited at approximately 1:15 PM EDT on September 25 by the 2001 Ecology class. The site is located on the Harrison-Crawford County line downstream from an extant old dam and bridge. The weather at the time of collection was overcast and windy (61o F). The site is located at elevation 561 feet at 38o 20'26.6" N Latitude and 86o 16'28.5" in the NE 1/4 of the SE 1/4 of Section 15 in Range 2E and Township 2S. We parked in a gravel parking lot that is used by Cave Country Canoes for stream access. We walked down a steep access path to reach the river.
Water flowing over the dam has gouged a deep pool along the base. From this location, water flows through two riffles separated by a smaller outwash community. The two areas of swift water then join forming a riffle/glide area that flows for a considerable distance downstream. On the opposite bank is an overflow race and pool. At this time of year, the race is normally dry, but often there is a large pool farther downstream. In past years, this pool yielded several sunfish, Kentucky spotted bass, and a large black crappie.
Site three's physiography is characterized by a mixed mesophytic forest that is part of the Eastern Deciduous Forest Biome, Shawnee Hills Natural Region, Escarpment Section. The general soils in the area are from the Elkinsville/Hagerstown Association. The bankside soils are the typical Haymond Silt Loam. This unglaciated area has a bedrock geology consisting of limestone and shale of predominantly Mississippian age.
Facing upstream, one would observe a substantial concrete dam with a bridge overhead, logs wedged against the dam, the plunge pool mentioned above, and two riffles separated by an outwash area. The study riffle is located in this direction on the left side. The dam was impeding the movement of leaves downstream, and a considerable organic detritus mass was being impounded by the low water.
Downstream, the watershed character on the right side was a steep wooded slope and a parking lot above the riparian zone. The site vegetation along the transect line was primarily sycamores, silver maple, and one osage oranges along the edge of the stream. The bank vegetative stability was optimal with more than 90% of each stream bank surface and immediate riparian zones covered by native vegetation. Vegetative disruption was not evident, and almost all plants were allowed to grow naturally. The stream banks appeared unaltered except for the path we used to access the stream.
On the left side is the outwash community and floodway mentioned above. This area is obviously scoured when the river floods sends water toward its path of least resistance. Therefore, the bank is covered with a stand of smaller silver maple trees. During this sampling period, we noted a great deal of trash, logs and other materials dropped into the area by floods.
The longitudinal profile of the stream at the time of collection indicated a shallow riffle and glide system with exposed bedrock, some gravel and a few larger boulders. The riffle velocity was 3 feet/second that produced a discharge of approximately 90 cubic feet per second.
The stream was cool with the water temperature measuring only 17.2° C. The water quality tests indicated a moderate alkalinity (13 gpg), and total hardness (19 gpg), ample dissolved oxygen (9.5 mg/L), and an alkaline pH of 8. Nitrate and phosphate levels were low (0.5 mg/L and 0.23 mg/L). Low fecal coliform bacteria of 9 and 12 coliform/ 100 ml were found at this location.
Invertebrates observed included aquatic worms, Asiatic clams, stoneflies, mayflies, helgrammites, caddisflies, snails, bloodworms, and riffle beetles. Our PTI of 32 suggested that the water quality at this site was excellent.
We visited this site hoping to find spotted darters in the riffle areas below the dam. Previously these darters were taken in this area in relatively large numbers on 25 July 1984. What we found instead were rainbow darters, greenside darters, banded sculpins, stonerollers and banded darters near the dam. Later, seine hauls produced spotted and bluebreast darters downstream from the study riffle.
