Water is
an essential element of Yosemite’s landscape. Many thousands of
years ago glaciers carved through the area creating the dramatic
vistas. Nowadays, winter snow and,
on
many afternoons,
summer thunderstorms help fill and replenish lakes, ponds and puddles,
feed quiet mountain
streams and flowing rivers, and produce slender trickles and dramatic
waterfalls. And of course the water sustains the Park’s
varied plant and animal
life. The animals include everything from pesky mosquitoes,
which find many
places to breed in ponds and puddles, to fish and frogs, which make
their home in and around the water, to those
stopping by for a drink. While thirsty hikers may well be
tempted to drink directly from cool
mountain streams alongside trails, the possible presence of
Giardia, a protozoan
parasite
which affects the digestive system, means that it is prudent to filter
or purify the water. Finally, after a long, hot hike, it’s
great to cool off in the river, although not directly above a
waterfall.
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