Tuesday, April 18, 2017

Pasture Stream Restoration

We were driving on a backroad in Oregon toward a lighthouse, and came across this site.  It looks a little like a cemetery, but its the opposite.  It's a nursery.

This is a really cool example of a pasture stream restoration project.   When cattle graze and are allowed access to streams:
  • they degrade the banks causing soil erosion (increasing sediment in the stream, which buries the habitat benthic organisms need to survive, and the habitat where salmonoid fish would lay eggs) 
  • the cows do their "business" in the streams (causing increased nutrient loading which leads to eutrophication and the increased success of noxious vegetation), 
  • maintaining a field means the stream banks are devoid of vegetation which causes more light to reach the stream, warming it (causing the stream temperatures to be too warm for salmonoid species, like trout, salmon, and steelhead). 
  • the shade plants are gone that many fish need for protection from predation.
  • the plants are gone that provided pollution filtration - no longer preventing pollutants (like the nutrients from the cow poo) from reaching the stream.
So, ecologists and resource managers restore the stream by protecting it from the cattle and replanting native vegetation.   Here, you can see how they've planted right up to the stream.  I can't tell what these plants are, but often folks plant willows and birches, which are fast growing and provide good shade and cover over the stream.  Notice that the cows are fenced and out in the field, not out in the stream stomping around making a mess. Also, you can see how the creek meanders in a natural way. Sometimes, when streams have been straightened to "improve" drainage, conservationists will have to dig new meanders.

Here, you can see the restoration area, and the new fencing designed to keep the cows out of the stream.

This is a stream crossing.  It's not available to the cows all the time, just when the farmer needs to move them.  

Here's a picture that shows the field, then the fence, then the restored area, stream, restored area, and other fence and other field.  Different states have different laws or guidelines concerning setbacks on streams.  For instance, many states have a 50' or 75' setback for logging.  This filter strip is not as big as that.  So, the farmer loses some space, but not too much, and its a big win for the aquatic ecosystem.  

The idea being to protect the stream / river resource by protecting the bit of the watershed near the stream / river.  Eventually, this restored area will protect the stream.

Just to give you an idea, here's an undisturbed stream in the native temperate rainforest a few miles away.  The stream above would have looked like this a hundred or so years ago.  Pretty amazing the change mankind makes in the world, huh?  The restored area will not look like this, but it will be an improvement and a compromise between the needs of nature and human/farmer.  Pretty amazing the change mankind can make in the world, huh?

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