Don't dam it!
More than 1000 dams have been removed across the United States
because of safety concerns, sediment buildup, inefficiency or having otherwise
outlived usefulness. A paper published in Science finds that
rivers are resilient and respond relatively quickly after a dam is removed.
"The apparent success of dam removal as a means of river
restoration is reflected in the increasing number of dams coming down, more
than 1,000 in the last 40 years," said lead author of the study Jim
O'Connor, geologist with the U.S. Geological Survey. "Rivers quickly erode
sediment accumulated in former reservoirs and redistribute it downstream,
commonly returning the river to conditions similar to those prior to
impoundment."
"In many cases, fish and other biological aspects of river
ecosystems also respond quickly to dam removal," said co-author of the
study Jeff Duda, an ecologist with USGS. "When given the chance, salmon
and other migratory fish will move upstream and utilize newly opened
habitat."
The increase in the number of dam removals, both nationally and
internationally, has spurred the effort to understand the consequences and help
guide future dam removals.
"As existing dams age and outlive usefulness, dam removal
is becoming more common, particularly where it can benefit riverine
ecosystems," said Gordon Grant, Forest Service hydrologist. "But it
can be a complicated decision with significant economic and ecologic consequences.
Better understanding of outcomes enables better decisions about which dams
might be good candidates for removal and what the river might look like as a
result."
Story Source:
The above story is based on materials provided by United States Geological Survey. Note: Materials
may be edited for content and length.
Journal Reference:
J. E. O'Connor, J. J. Duda, and G. E. Grant. 1000 dams
down and counting. Science, April 2015 DOI:10.1126/science.aaa9204
Cite This Page:
United States Geological Survey. "Dam removal study reveals
river resiliency." Science Daily,
30 April 2015. <www.sciencedaily.com/releases/2015/04/150430145120.htm>