Sunday, November 14, 2010

Stream Nutrients

Determining the health of a stream is complex, especially when you factor in the factors of location, soil, and especially the impact of human activity on the watershed.  Any attempt to develop a standard scale is all the more difficult.
Take for example the nutrient levels of  total nitrogen (TN) and total phosphorus (TP).  In the words of the Missouri Department of Natural Resources on the DNR Website:
"Too much nutrient loading to a water body can cause rapid growth of algal blooms, organic enrichment and depletion of dissolved oxygen. Too little may result in insufficient enrichment of the aquatic food chain, which would be detrimental to a healthy aquatic biological community."
It is complicated further by the varying geology and human density around the state, making it difficult to set a standard for the state.  A heavily karst region like the Ozarks will have smaller nutrient levels that a muddy Northern Missouri stream.  The answer to which is better?  "It depends."
One thing we know is that our Stream Team monitoring is an important tool in the assessment of the stream health.
"An assessment of algal, macroinvertebrate, and fish communities in streams with low-level nutrients found that algal communities correlated well with increasing nutrient levels. Using algal community data to investigate nutrient conditions have been shown to be a successful method in many water-quality monitoring programs."

Unfortunately, there are tremendous scientific and political opinions on what Numeric Nutrient criteria should be.  I suspect that any criteria put out, like many other solid numeric criteria such as the econimic numbers we read daily, will be the "best guess" available at the time, interpreted by the organization with the "Final Word.'
This isn't meant as criticism, just an observation that with complex data, sometimes you just have to take a position to believe in and adjust it later.  In the words of a famous philosopher:

"Everybody should believe in something. I believe I'll have another drink."
                              — W.C. Fields
David Casaletto* wrote the story in the Ozarks Water Watch newsletter quoted above that has a lot of good information on the subject.  This is a great resource for other local water issues and is available by email simply by signing up at http://www.uwrb.org/

* David Casaletto is the President and executive director of Ozarks water Watch and Acting executive director of Table Rock Lake Water Quality.

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