Figure 5.— Aerial photograph of the Navajo surface mine in New Mexico, showing mining operations proceeding 10 miles 

 toward the south. A single 16-foot bed in the north and four thin coalbeds in the south are being mined. The associated 

 Four Corners powerplant and its cooling basin are in the center. This mine is in an area of less than 10 inches of rainfall per 

 year, and irrigation is being used to reestablish vegetative cover on the graded spoils. Haul roads that are perpendicular to 

 the working cut were not completely covered because of continued mining. November 1978. 



and scale. What seems acceptable in laboratory 

 studies or on experimental plots at mines may 

 not be successful for a large area over long 

 periods of time, and results can vary widely with 

 changes in local reclamation techniques and 

 with climatic factors. These problems were 

 generally recognized in one of the most com- 

 prehensive field examinations to date on the 

 revegetation potentials of western coal mines 

 (Packer and others, 1981). The authors of that 

 study examined 28 of the major western coal 

 mines in 1976 and 1977; until 1976, revegetation 

 had been attempted at only 36 western coal 

 mines. Although expressing qualified optimism 

 for success, they indicated that a reassessment 

 in 5 or 10 years would be needed. Their study 

 included maps of the Western States that show 

 locations of surface minable coal, soil associa- 

 tion types, potential natural vegetation types, 

 the average annual precipitation, and length of 

 growing season. 



REGIONAL CHARACTERISTICS THAT 

 AFFECT RECLAMATION 



LANDFORM AND CLIMATE 



The western coalfields, although extending 

 over almost 18° of latitude, have some common 

 geographic features. They occur on high plains, 

 dissected plateaus, and mountainous foothills 

 at elevations above 2,000 feet, and many occur at 

 elevations of 5,000 to more than 6,000 feet. The 

 climate is continental and semiarid. The mean 

 annual precipitation (fig. 15) in most areas is be- 

 tween 7 and 15 inches, reaching about 19 inches 

 in the higher elevations in Colorado. Evaporation 

 rates may be three times greater than the precip- 

 itation rate. The amount of precipitation varies 

 widely from year to year, and droughts are com- 

 mon. Except in the higher elevations in Colorado 

 and Utah, most of the precipitation occurs in the 



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