Project History

In 1998, approximately 100,000 CY of sediments were discharged to a 5-mile section of Fawn River, in Steuben County, Indiana as the result of a rapid draw down of an upstream reservoir (the “Event”). The quantity of the sediment discharge was magnified by two prior herbicide applications in the reservoir, spaced one year apart, followed by three years in which sediments destabilized as anchoring vegetation and root masses rotted.

Figure_1

Fawn River was also beloved place of family recreation.

Prior to the Event, Fawn River below the Orland dam was recognized as one of the best preserved sections of river in the State of Indiana. Fawn River had a narrow, deep, swift thalweg, with alternating pools and runs, desirable water quality, a clean, porous, gravel hyporheos interconnected with up-welling springs, and a riparian corridor under conservation easements protecting undisturbed woodlands, wetlands and calcareous fens.

The “Bible” of Indiana natural areas described the pre-Event lower Fawn River as:

Event (2), 1998

This stream reach of nearly 5 miles . . . rivals any other in the State for combined biological interest and feasibility. . . . The upstream half of this stream averages about 25’wide but it is quite swift and relatively deep with a uniform bottom of fine gravel . . . . It is here a miniature “wild river” reminiscent of cool swift streams of the upper Lake States.

Indiana Natural Areas, Lyndsey, et al., 1968, pp. 408-09.

 

Event Footage

The Effects

When the massive sediment flow entered the river in 1998, its aquatic life was immediately imperiled; including, a large fish kill from abraded and plugged gills, and mussel and macro-invertebrate colonies were rapidly buried under the silt and sand. This hyper concentrated flow (> 60% solids) deformed and buried the gravel bottom, filled the deep pools and cuts with silts and sand, and reduced connectivity  to the underlying aquifer by plugging the hyporheic pores.

Click here to view images from the Event →

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