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Show gardens." Seeps usually appear where a canyon has been cut through an aquifer or has intercepted a water- bearing joint connected with an aquifer. Most commonly, the aquifer is the Navajo Sandstone. Springs in the recreation area are more often found in intermittent drainages where subsurface flow finds an outlet. Occasionally, they are found in upland alcoves or beneath perched aquifers. Springs are not common in the NRA; they sometimes discharge only seasonally or diurnally. Springs usually support a water- dependent plant community and associated fauna. A special case of spring flow occurs between Glen Canyon Dam and Lees Ferry, where several spontaneous, copious flows from the lower canyon walls have begun in the past few years. These springs are believed to originate from Lake Powell bank storage in the Navajo Sandstone. Waterpockets, or natural bedrock depressions, are the most numerous source of surface water in the uplands of Glen Canyon NRA. They occur where rain fills depressions weathered into exposed sandstone surfaces. Most waterpockets are ephemeral, although some are large enough to be virtually permanent. Waterpockets often support a diverse assemblage of invertebrate fauna such as water fleas, amphipods, fairy shrimp, and insects, and in some cases amphibians such as the canyon tree frog. These animals are important food sources for native terrestrial fauna and a source of interest for recreationists. Threats to these three water sources are varied. Seeps can be depleted by mineral development on adjacent land or by use of the aquifer recharge water for development. Springs are subject to these same threats, and additionally they can be fouled by cattle. Waterpockets are not threatened by development affecting the subsurface, but because they are used by cattle they are vulnerable to surface pollution. Waterpockets are in serious need of formal study to document their biology and their role in the desert ecosystem. The chemical quality of water from springs and seeps in the recreation area is usually quite high. Williamson ( 1985) performed chemical profiles on 13 surface seeps and springs in the NRA and found anions, cations, and trace elements to be well within the " normal" range for waters in this region. III. G. 2. Management alternatives. Alternative A: No action Under this alternative no additional information would be obtained on seeps, springs, or waterpockets. Future proposals potentially affecting water resources, such as mineral leasing, could be inadequately evaluated due to poor baseline information. Sensitive ecosystems or unusual biota may remain unidentified. 38 |