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In 2004, Western New York received large quantities of rain as a result of the hurricanes that struck Florida then moved north and stalled over New York. During one such storm event, over 450 feet of a seven-foot high streambank on Chautauqua Creek in Chautauqua County, New York, eroded back eight feet, eliminating a popular fishing trail and dumping over 1,200 tons of sediment and multiple large trees, root mass and all, directly into Lake Erie, only 700 feet downstream. The sediment plume from the erosion could be seen extending from the mouth of the creek ¼ mile to nearby Barcelona Harbor. Since the storm, the bank experienced a very severe lateral recession rate of over ½ ft. per month. |
| After the storm, the trees, pools and fish habitat were destroyed leaving raw eroding banks, gravel bars and an exposed stream. Chautauqua Creek is listed by the New York State Department of Environmental Conservation as a prime trout stream with thousands of people fishing this stream for steelhead trout for eight to ten months of the year. The stream is also a known location for the endangered eastern sand darter. People interested in fishing used to access the stream by a trail from a nearby parking location. Since the storm event the trail has been closed due to hazardous bank undercutting along the creek. | |
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The approved design called for the installation of approximately 450 linear feet of large, 4’x3’x3’ 4,500 pound blocky limestone rocks to be used to re-establish the toe of the stream bank. The toe rocks provided a stable base on which to support large flat bank rocks and large blocky rocks stacked on top of each other. These stacked and placed bank rocks were designed to be of sufficient size and weight to withstand heavy ice jamming, the high flow velocities of the creek, and to protect the newly created bank slope from erosion. To anchor all of the rock into stable ground, and to protect the slope from undermining from behind, four “key ways” were to be dug back 20 feet perpendicular to the stream into the natural bank. The key way trenches would be filled with a gradation of limestone rocks that interlocked with the rocks on the stream bank. |
| To redirect the thalweg, or normal stream flow, from the base of the toe stones, single stone benway weirs were designed at approximately 50 foot intervals along the toe. Each weir stone would be pinned to the shale bottom using steel rebar to keep them in place. Above the bank rock, large scale plantings of native vegetation were designed to reduce flood level velocities, restore shade and provide a food source for improved fish habitat. Large scale or whole tree transplants, willow curtains and willow stakes were installed. To protect the project site from surface erosion, the entire site has been seeded with a seed mixture specially mixed for streambank restoration. | |
