Gravel Mining part 3

An intensive study was undertaken on July 7, 1980 due to an extended period of 100 +F air temperatures when solar intensity on the stream bottom was near maximum. Flow and temperatures were measured above and below the mouth of every spring tributary branch on the stream.

The major source of flow in the study area, except during periods of precipitation, is from seven surface springs, three above the gravel plant and four below. During low flow the uppermost three springs contribute 8 cfs of 57 degree F water which passes through the Havin lake. An additional 16 cfs of spring water at the same temperature is added by the four springs downstream from the lake over the course of about 1 mile. About 1/4 mile of stream an either side of the lake has been channelized by previous dredging. Consequently, all canopy vegetation has been removed and the stream is open to direct solar radiation. An intensive study was undertaken on July 7, 1980 due to an extended period of 100 + degree F air temperatures when solar intensity on the stream bottom was near maximum. Flow and temperatures were measured above and below the mouth of every spring tributary branch in the stream.

The results showed a temperature increase of 30 degrees F between the spring discharge above the Havin pond where the permanent stream flow originates and a point downstream where flow from the first downstream spring enters. The addition of 4 cfs at this point lowers the temperature from 90 degrees F to 77 degrees F. Stream temperature was further characterized by gradual increases between points of additional entry of spring flow due to high ambient temperatures. However, the steepest point on the temperature curve or the zone of greatest observed temperature increase corresponded to the ponded water on the Little Piney River at the Havin lake. The channelized portion of the stream also undoubtedly added to the thermal increase which was never completely overcome by further additions of spring flow.

The author of this study concluded the 86 degrees F temperature, measured upstream from Table Rock Spring was lethal to any trout present. Down- stream from Table Rock Spring where temperature. were cooler (75-80 degrees F) it was inferred there were no surviving young-of-the-year which are more sensitive to thermal increases. The juvenile and adult trout in this same area were believed to be under considerable stress. Downstream from Lane Spring the water cooled further to nearly 70 F and the trout were probably unaffected. Unfortunately, almost all of the natural trout spawning had historically been upstream from Lane Spring where the thermal stress had been greatest.

In addition to the projected trout losses, the put-and-take trout stocking program had to be cancelled until temperatures cooled later in the season. In addition to the thermal increases, Havin processes gravel, returns wash water to the stream and substantially increases turbidity downstream in the trout management area. The Little Piney River is normally a clear stream with visibility extending to the stream bottom, which may reach 5-6 feet in pools. Any increase in turbidity in this type of stream is aesthetically damaging and can restrict recreational uses. Some of the serious complaints have come from fishermen, especially fly fishermen who rely on trout to spot surface laid patterns through several feet of water. In addition to a turbid washer effluent, turbidity generated from the actual dredging within the onstream lake or within the stream is sufficient to warrant complaints in downstream areas on the river. This problem is not unique to the Little Piney, but is virtually characteristic of almost any free-flowing stream in the Ozarks where gravel mining takes place. The streams in this physiographic region are noted for unusual water clarity and are in high demand for recreational use. Turbidity in these streams is aesthetically damaging to recreational users expecting a high quality experience. Certain aspects of fishing and canoeing are adversely affected for many miles below problem sources of turbiditv.

CONCLUSIONS

The quantity of sand, gravel, and stone is the second largest non-fuel mineral mined in Missouri. Because of its low value and high transportation costs, sand, gravel, and stone are produced near the point of use; therefore, the industry is concentrated in large rapidly expanding areas or where other large-scale projects are under construction. This places the industry in direct competition with other land use and in-some instances alternative stream use for fish, wildlife and recreation.

The industry faces the problem of any mining practices which can affect the environment. From a fisheries and wildlife viewpoint the few positive aspects that instream dredging might afford, such as deepening of pools, are far outweighed by the detrimental aspects of the mining process. Off-stream mining should be encouraged wherever feasible and would have very few adverse effects if the channel integrity and a buffer of riparian vegetation remained intact.

The two case histories discussed pointed out significant problems that need to be addressed in further regulation of the industry. Present guidelines are largely ineffective and in some instances promote the location of sand and gravel mines in or near river channels. This maximizes the potential for environmental conflict. An effective effort most be made to reduce water pollution, reclaim areas, and improve the overall operation of facilities. The industry and users of the product must recognize the time and costs required to protect the environment. Overregulation is a concern, but historically and in perspective with many other states, the industry has operated freely in Missouri. Concern for development of the resource needs to be properly balanced with available technology that will also protect fish, wildlife and recreational use.