Ponds and Lakes ivith Excavated Basins 27 



or the runoff water from higher lands may flush out the stripmine lakes, 

 removing some of the acidic material. Occasionally, stripped lands ad- 

 jacent to small rivers are flooded by the latter, resulting in a great improve- 

 ment in the sulfate composition of the stripmine water after the flood 

 recedes. 



In many respects, stripmine lakes are similar to gravel-pit lakes, but 

 they usually differ markedly from them in the acid and mineral content 

 of the water. Stripmine waters usually contain several hundred parts per 

 million of sulfate; in one instance, fish were found living and reproducing 

 in a mine pond that contained 1500 ppm of sulfate. 



Stripmine ponds vary considerably with one another in the weight of 

 fish supported because of their great range of dissolved salts. It is reason- 

 able that fish production might be low in new stripmine waters, since 

 many invertebrate animals and algae in the food chain are more sensitive 

 than fishes to abnormal mineral content. But aging, weathering, flooding, 

 and the annual accumulation of dust and leaves gradually build up the 

 basic fertility and reduce the chemical imbalance of these waters until 

 they become very fertile. ^^ The waters of the South Polly wog Association, 

 an 80-year-old stripmine area in Vermilion County, Illinois, support 

 populations of miscellaneous fishes as high as 750 pounds per acre. 



Quarry Lakes 



A great deal of limestone is used in agriculture as limestone dust to 

 neutralize acid soils and as crushed rock in road building and other 

 construction. Other deposits of rock of value in building may be quarried 

 from near-surface deposits. Quarrying and strip mining operations are 

 somewhat similar in that often the top soil and overburden are first 

 removed, leaving the strata of limestone or other rock exposed. In quarry- 

 ing, limestone and other rocks are subsequently loosened by blasting, 

 and loaded in large trucks by cranes. Then, the blasted rock (the lime- 

 stone portion) is taken to a rock crusher capable of producing particle 

 sizes, from limestone dust to rocks as large as hens' eggs. Since deposits 

 of limestone are often below the level of tlie water table, quarrying 

 operations depend upon pumps to remove the water as it seeps into the 

 quarry pits. 



When all of the valuable rock has been extracted, the pumps are 

 stopped and the pits fill up to the level of ground water (Figure 2.4), 

 forming one or several bodies of water. New limestone quarry waters are 

 usually quite infertile because they contain almost no phosphates, nitrates 

 or organic material. However, minerals causing hard water are present 

 in abundance and organic nutrient materials may be carried into quarries 

 through surface runoff from surrounding lands, so that the production of 

 fish may increase quite rapidly as the water in the abandoned quarry ages. 



