We really do not have an energy source that in some way is not destructive to our environment................We know about the CO2 impacts on temperatures and health related conditions(asthma)from oil, coal and gas extraction,,,,,,,,,,,,,,,,,,,,,,We know about the radioactive material waste generated by Nuclear power plants..................And if we are honest with ourselves, we know that currently, there is no such thing as renewable green energy via putting 300-500 foot windmills on our mountain, forest and prairie lands (or) carpeting our deserts with solar panels....................Both of these create new industrial zones in what was once open space, kill off wildlife and require extensive ripping up of land to put transmission lines and such infrastructure to get the energy to where people live........................Fracking for natural gas poisons aquifers, lakes and rivers via the chemicals pumped into the ground to release the gas...................................And our outdated dams destroy the biological diversity and carrying capacity of our river system as the article below reinforces.....................I am all in favor or solar panels on every existing structure on the planet----This, the one endeavor that does not further degrade biodiversity(except in the mining of the minerals needed to make the solar panels(oops!).................................So you see blog readers, for us to exist as a modern society, neither the democrats pushing the false narrative of wind and solar as renewables or the Republicans pushing more coal, oil, and gas,,,, have the answer to a clean source of power..........................Our best and brightest minds will have to figure out how to harness nuclear fusion(not fission which is our current nuclear plant paradigm) or come up with something that none of us know about for green energy to truly come into play as a reality

http://feedproxy.google.com/~r/sciencedaily/plants_animals/~3/_JdZpQMBKr8/170510174855.htm?utm_source=feedburner&utm_medium=email

Fish should figure into fate of nation's aging dams

As nearly 75 percent of the nation's largest dams approach the high maintenance years, safety and economics figure large in decisions to fix or replace. A recent study by Michigan State University (MSU) researchers makes a case to consider how those dams affect the streams and fish that live in them.

This is a distribution of the 49,468 large dams for the conterminous USA.

Credit: US EPA, 2006

Big dams -- many approaching 50 years old -- span the United States. In some areas, like the northeast, there are many and close together. In other areas like the southwest, dams are sparser and further apart. It's not just the presence of a single dam that can affect streams by increasing or decreasing flows or fragmenting streams and creating dead ends for fish. The group showed that multiple dams throughout watersheds can have cumulative effects on a stream and its fishes. This underscores the fact that effects of dams could affect habitats and fish miles away from a single dam.

The report, published in the May edition of the journal Science of the Total Environment, also shows how several aspects of streams and dams must be examined and considered to understand a dam's role in an ecosystem, said Arthur Cooper, the paper's primary author and a research assistant in the Aquatic Landscape Ecology Lab.

"This study advances our ability to understand the effects of dams as a landscape-scale disturbance, providing information vitally needed to prioritize dam removal and management, informing policy and decision-making to improve and conserve the nation's stream resources," Cooper said.Barton Dam in the Huron River in Ann Arbor, Michigan

The group scrutinized 49,468 of the nation's dams -- those considered the largest and used for a wide variety of purposes, like hydropower, flood control, water supply and irrigation. By looking at how those dams affect different groups of fishes, it became clear dams benefit certain types of fishes while negatively influencing others. In particular, some trout and darter species that prefer fast-flowing streams and streams lined with gravel, or that are considered generally intolerant to human disturbances, decline in numbers with dams.

But the widespread changes in stream flow and the creation of lake-like environments formed by reservoirs above dams are associated with more sunfish in some regions of the U.S.

And Cooper said this isn't just about streams closest to the dams. Dams and their reservoirs deliver a cumulative effect, leaving their mark on streams further upstream.

"Dams have not only fragmented large rivers themselves, but their main tributaries are also truncated by dams," Cooper said. "This is analogous to a tree having its trunk cut in half and many of its main branches removed."

Cooper said this information has been used in a national assessment of stream fish habitats conducted in support of the National Fish Habitat Partnership. Along with other disturbances to stream habitats such as urban and agricultural land use, mines, and point-source pollution, the group is working to identify the condition of and threats to streams nationally.

Besides Cooper, "Assessment of dam effects on streams and fish assemblages of the conterminous USA" was written by associate professor Dana Infante, the leader of the aquatic lab and a member of MSU's Center for Systems Integration and Sustainability; Wesley Daniel, Kevin Wehrly, Lizhu Wang and Travis Brenden.

"This study offers new insights into the variable effects that dams can have on stream fishes," Infante said. "This information is important for stakeholders who may be working to conserve stream habitats, considering dam removals, or planning development of new dams. So that others can benefit from the tremendous amount of information assembled for this project, all dam metrics that we calculated are publically available through this publication."

Partners are using this information to prioritize where and how to protect or restore streams. Managers involved in dam removal decisions throughout large regions could also use this information to compare locations for dam removal that would have the greatest ecological benefits.

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Story Source:

Journal Reference:

1. Arthur R. Cooper, Dana M. Infante, Wesley M. Daniel, Kevin E. Wehrly, Lizhu Wang, Travis O. Brenden. Assessment of dam effects on streams and fish assemblages of the conterminous USA. Science of The Total Environment, 2017; 586: 879 DOI: 10.1016/j.scitotenv.2017.02.

Date:

May 10, 2017

Source:

Michigan State University