Abstract

Fifty-four of the 58 springs reported here as principal springs yield 5 to 200 gpm. The other four and 140 more springs in the Henry Mountains yield less than 5 gpm. All springs that yield 5 gpm or more rise on the slopes of Mt. Ellen, Mt. Pennell, or Mt. Hillers, the three highest mountains in the range. Only springs that yield 1 gpm or less rise from Mt. Ellsworth and Mt. Holmes.

Water that supplies the springs of the Henry Mountains area is stored in small, generally highly permeable, colluvial or alluvial aquifers in the mountains and in pediment gravels or sandstone beds in the areas that flank the mountains. The source of the water is principally snowmelt and hence the yields of most of the springs tend to be higher after winters of high or normal snowfall than they are after winters of low snowfall. Thus the springs cannot be expected to give year-in, year-out dependable yields. The temperature of the spring water as measured in the summer ranges from near freezing where close to the snowmelt source to about 30°C (86°F). The higher temperatures are appreciably above the mean annual air temperatures and thus are attributed to warming of the water by the sun, for many of the aquifers are close to the land surface. Most of the spring waters are of calcium carbonate type, and many whose sources contain igneous materials are fairly high in silica (SiO₂), whereas some of those whose sources are in the sedimentary rocks flanking the mountains are high in sulfate (SO₄). Spring-fed Birch Creek loses some of its calcium carbonate as its temperature rises, and likely most of the other spring waters behave similarly.