Gravel Mining in Missouri
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From a report by RONALD L. CRUNKTLTON.
Fisheries Research, Missouri Department of Conservation
1110 College Avenue, Columbia, Missouri 65201.

Sand, gravel and stone is the largest non-mineral industry in the United States and Missouri is ranked 20th nationally in sand and gravel production. Since the mining industry typically operates in the expanding fringe areas of cities or near associated recreation areas, multiple use conflicts are likely to result. Certain segments of the industry have a direct impact on fish and wildlife or indirectly affect the recreational use of those resources.

In 1980, eight million tons of sand and gravel were mined in Missouri. The principal sources of sand and gravel are the alluvial deposits associated with streams and floodplains. Low unit value, high bulk density, and high transportation costs cause major production sites to be located near large metropolitan areas. More than 50% of the states total production is centered in the four county area near metropolitan St. Louis. The potential sand and gravel production from the Mississippi and Missouri rivers and the Ozark region is virtually unlimited and supplies will remain far into the future. The two basic types of sand and gravel mining employed in the state are open pit excavation and dredging.

Open pit extraction is not as harmful to the stream environment as river dredging because most operations are located off-river. However, mining sites located near a stream channel or on the floodplain are of great concern and can produce some adverse effects even if the river channel is not physically altered. Site clearing on the floodplain and removal of riparian vegetation may lead to alteration of the runoff pattern, increased erosion, bank destabilization, sedimentation and turbidity. These direct effects of off-river excavation may not be as damaging to the environment as the methods of processing mined materials. Construction specifications requires essentially all sand and gravel to undergo washing to remove silt and discharges from washing operations are a predominant source of environmental problems.

The practice of instream gravel removal or dredging is quite different from open pit extraction and varies greatly with the size of the operation and the composition of the material to be removed. Larger operations use a suction or bucket-type dredge mounted on boats or barges. Equipment used in smaller operations range in size from a crane and dragline dredge bucket to a front loading or earthmover that can operate in shallow streams.

Adverse effects of dredging may include:

A. Modifications of the Stream Channel

1. Alteration of habitat a. creation of deep pools b. loss of riffle habitat 2. Alteration of bed load transport 3. Increased head cutting 4. Alteration of channel flow 5. Bank destabilization

B. Modifications of Water Quality

1. Increased turbidity 2. Reduced light penetration 3. Reduced photosynthesis (primary production) 4. Increased stream temperature due to ponding and removal of riparian vegetation 5. Resuspension of organic material resulting in increased oxygen demand 6. Resuspension of toxic materials associated with sediment such as pesticides or metals.

C. Modifications of Aquatic Populations

1. Physical elimination of mussels, and other macroinvertebrate life 2. Destruction of spawning beds, and nursery, habitat 3. Reduction and/or elimination of silt intolerant organisms 4. Enhancement of silt tolerant organisms 5. Alteration of food web

D. Modification of Recreation

1. Change in fish species composition 2. Reduced fishing success 3. Aesthetics

Continued excavation of an open pit mine and the floodplain can result in many of the same environmental problems as dredging. Many operations that originate on the floodplain progressively enlarge, encroach upon and eventually capture. the adjacent stream channel. Thus, the open pit becomes contiguous with the stream and can result in a compounding of the adverse consequences of both open pit and dredging practices. One of the most serious outcomes is the subsequent ponding resulting from the excavated pit. This in association with the removal of riparian vegetation can result in abnormal thermal increases, which can have far reaching environmental effects on downstream aquatic communities. This has been particularly damaging in Missouri streams that normally support a coldwater fauna.

INDUSTRY REGULATION

Regulation of the industry in Missouri is based on the Missouri Land Reclamation Act, the Missouri. Clean Water Law, and the Federal Clean Water Act. The Missouri Land Reclamation Act requires registration of all active mining sites. It has no provisions for setting guidelines for extraction procedures, but does require reclamation of worked sites. In part, the purpose of the act is to "encourage the planting of forests, to advance seeding of grasses and legumes for grazing purposes and crops for harvest, to aid in the protection of wildlife and aquatic resources, and to establish recreational, home and industrial sites. All ridges and peaks of overburden must be reduced to a minimum of 20 feet at the top or the affected land must be graded in a manner that the area can be traversed with farm machinery."

A serious weakness of this law is that mining sites in the river or floodplain are exempt from the reclamation requirements which has resulted in an economic advantage and has effectively kept the industry in or near the river channel where reclamation costs are not a factor. It also places the industry in a position that maximizes the potential for environmental conflict.