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The Blue River site at Stage-stop Campground is located near Highway 62, about eleven miles west of Corydon, Indiana near the Harrison and Crawford county line. The nearest post office is located in Leavenworth, Indiana. This site was evaluated on September 7, 1999 at 1:15 P.M. The weather was sunny and hot with an air temperature of 92 F. The water level of the stream was extremely low this year due to an extended drought.
We walked down the canoe area access path at the campground to the riffle. The flood plain around the site has mainly recreational usage, but occasionally some land is leased for corn and soybean production. The riverbank slopes steeply down the canoe access path to the river. Along each side of the path, we noted large riparian trees and various understory plants on the hillside. The dry section of the river bed was covered with gravel and larger rocks, and it was obvious that water normally covers most of the area where we were walking.
We walked approximately 25 yards west to a long riffle area where we performed our analysis. It was interesting that this portion of the river was re-channeled by canoers so that they could pass through at low water levels. We initially suspected that this activity may have had a profound effect on the darter populations, but this fear was later allayed when we started finding the darters. The re-channeled river water was directed almost completely down the center of the stream. The end result was that the water was deeper and moved more swiftly than when the water is spread more evenly across the entire riffle complex.
Stage-stop's physiography is a mixed mesophytic forest that is part of the Eastern Deciduous Forest Biome, Shawnee Hills Natural Region, Escarpment Section. Bankside soils were classified as sandstone derived soils that included Haymond silt loam and Pekin silt loam soils. The Haymond silt loam soils are well drained on bottom lands in basins of sinkholes in uplands. Furthermore, the Pekin silt loam is a flood plain where the land plateaus up from the river. The region has common karst features with rugged hills situated along the eastern border of the region.
The general area included a variety of forested habitats, a campground with the appropriate amenities, and a strip of riparian bankside vegetation along the stream. The canopy cover ranged from open (no shading) to partial shading of the stream. There was evidence of animal usage (raccoons and deer) along the banks and near the stream. The river's banks were steep and eroded indicating frequent flooding. The stream bed consisted of gravel, cobble and boulders minimally embedded by fine silt. Where the river was redirected, there were shallow pools of water on each side. Again, we know from frequent visits to this site that this area is normally part of the riffle habitat.
The altered riffle at Stage-stop had the following characteristics. The riffle was positioned between long pools of water. Upstream, we found that the pooled water was six feet in depth. Approaching the riffle, the water developed into a glide as it entered the riffle proper. The riffle study site was approximately 140ft. in length and 16ft. wide. The average depth of the riffle was 0.923ft. with the deepest part being 15.5in. deep. The average velocity of the riffle was 4.8ft/s. The discharge of the riffle was calculated to be 72 cubic feet per second.
The water quality of the river was what one would expect for a forth order stream. Water quality tests indicated that the water was well oxygenated during its travel over the rocky habitat. The pH was slightly alkaline (8), and a conductivity measurement of 0.46 mS/cm indicated moderate amounts of dissolved solids and electrolytes. The nitrate content of the river at this site was 0.7 mg/mL, and the phosphate was 0.47 mg/L. Fecal coliform bacteria analysis for this site indicated 13 per 100mL of river water which is within the range considered safe for recreational use.
If a person were to stand in the center of the river at this site and face west or downstream, the individual would observe a shallow, calm area followed by a long, 20 yard riffle area affected considerably by human alteration of the rocks. The substrate here was mostly sand, gravel, cobble and some boulders. There was a seasonal growth of water willow located on either side of the river as well as a riparian component of large sycamores and silver maples. On the left side of the riffle was a gravel outwash community gravel bar covered with vegetation. We positioned our equipment on an exposed gravel bar on the right side approximately twenty to thirty feet from the riffle.
Facing upstream, one would note the calm, deep pool mentioned above. We did not determine the length of this pool, but it extended well beyond a bend in the river. Several large fish were observed using snorkeling equipment and wading. Furthermore, several overhanging trees shaded the area. On the south bank, a large hill was forested by several hardwoods including silver maples and sycamore in the riparian zone and other hardwoods when the vegetation assumed the upland configuration of the river. Even though this side had extremely steep banks leading up the hill, it was stabilized by the large trees and abundant understory. The opposite bank with foot and canoe traffic was eroded exposing the soil and many tree roots.
The macro-invertebrates observed were taken using a triangular kick net (TKN). Our TKNs yielded stonefly nymphs, mayfly nymphs, caddis fly larvae, dobson fly larvae, snails, young Asiatic clams, gray midge larvae and fresh water mussels. The PTI water quality rating of 25 indicated that the stream quality at this location is excellent.
Since the river had been manipulated to form a single riffle area, we used this to our advantage and collected the entire riffle system at this site. In our analysis, we found stonerollers, hogsuckers, banded darters, spotted darters, greenside darters, bluebreast darters, emerald shiners, log perch and banded sculpin. Interestingly, we found no juvenile spotted darters here. Perhaps the rocks were moved during darter breeding season.