Mining Gravel and Protecting Streams

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Published on: Oct. 2, 2001

Last revision: Nov. 9, 2010

Owners of streamside land have always faced flooding and erosion due to natural events, but damages caused by in-stream mining should not be an additional threat to personal property.

More than 500 in-stream mining sites exist in Missouri. Considering the potential harm any one gravel mining operation can cause, it is important that gravel mining occur only with proper safeguards.

Missouri's streams are vulnerable to huge problems caused by gravel mining. These waterways have formed within their valleys over thousands of years. During this period, the stream meandered across its flood plain. Because this movement of the stream channel happens very slowly over many years, natural erosion occurs at a rate to which the stream can adjust.

The characteristics of a given stream are not formed on hot summer days when there is little water flowing in the channel. Instead, our streams are carved out during periods when the stream channel is flowing at least half full. During high flow, the water has enough power to cause changes.

Streams are a series of alternating deep areas called pools and shallow areas called riffles. Riffles are high areas of the stream bottom that control the slope of the stream. It's because riffles help control the slope of the stream that they work to control erosion.

Generally speaking, erosion occurs on outside bends and silt, sand and gravel deposition occurs on the inside bends. This process produces the sinewy characteristics that we are accustomed to seeing as we float, fish or swim in our favorite stream.

Gravel mining often results in piles or pits that, during high water events, can rapidly increase the erosive process in streams.

Although many of our streams have plenty of gravel to spare, we also have many streams which cannot afford to have gravel removed from them. To ensure you are mining from a stream that has ample gravel, look for some key characteristics. Streams with excess gravel generally have gravel bars with little or no vegetation growing on them. The rocks are generally small (less than three inches in diameter) and are loosely packed.

Gravel bars that are vegetated or where the rocks are tightly packed (not easily loosened when kicked) are characteristic of healthy streams with just the right amount of gravel. These should not be disturbed.

When practical, rock aggregate should be acquired from non-stream sources such as nearby rock quarries, but if you must remove sand or gravel from a stream or its

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