Laserfiche WebLink
local Soil Conservation Service (Hill, 1980). Table 2.7-12 gives estimates <br />of average annual yields for the Trapper Mine drainages. Most of the runoff <br />occurs during the months of April, May and June, while the crops need water <br />mainly in July and August. The runoff from any of the major drainages in <br />the Trapper Mine would not supply water for continuing irrigation. Evapor- <br />ation and pond seepage would probably use at least half the runoff water. <br />For example, the estimated annual yield of Pyeatt Gulch is 154 ac-ft. This <br />would probably irrigate only 20 to 38 acres for average years after losses. <br />Irrigation of lands in drainages with fill material with surface water from <br />the Trapper Mine drainages would therefore not be economical. <br />In most samples, the natural molybdenum concentration in surface runoff from <br />the Trapper Mine area has exceeded the recommended limit for continuous <br />irrigation use. Table 2.7-18 should be consulted for concentrations of <br />• molybdenum in surface runoff from the Trapper Mine. Copper, iron, lithium <br />and manganese have exceeded their recommended limits in a few samples. <br />Total dissolved solids have been close to the upper recommended limit and <br />would probably exceed the limit at times with evaporation in a holding reser- <br />voir. Therefore, the water quality from the Trapper mine drainages would <br />probably not be suitable for irrigation at times, even if sufficient water <br />was available. <br />r_.-,.,.., a..., . e.- <br />Groundwater conditions for the Trapper mine have been presented in Section <br />2.7.5 Additional information on the ground-water conditions at the potential <br />AVF sites is presented in this section. Monitoring wells were drilled in <br />Pyeatt and Flume Gulches because the geologic information indicated that <br />• these two gulches have fill material and have the most potential to be im- <br />patted. Data on completion of wells and pump tests which were used to define <br />2-539 <br />