Debra S' Baker and Donald G' Huggins

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Nutrient Trends in Reference Streams of the
Central Plains

• Debra S. Baker and Donald G. Huggins

Central Plains Center for BioAssessment
Kansas Biological Survey, University of Kansas
30th Annual Great Plains Limnology Conference,
Lincoln, NE, 10 11 October 2003
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Nutrients in Streams

• Clean Water Action Plan 1998 - USEPA initiative
  to establish regionally-based nutrient criteria
  for waterbodies via Regional Technical Assistance
  Groups (RTAGs).
• Develop a dataset of nutrient levels found in
  reference or least impacted streams of USEPA
  Region 7.
• Should criteria be single values for the entire
  EPA Region, or should criteria be based on a
  subset of stream characteristics, such as
  ecoregion?

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Stream Sites
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Parameters

• in situ
• DO, turbidity, pH, conductivity
• Lab analysis
• TN, NH4-N, NO3-N,
• TP, PO4-P,
• chlorophyll a, phaeophytin a

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Hypothesis

• Streams will show affiliations based on some
  suite of water quality characteristics (e.g.
  nutrient concentrations).
• Principal Components Analysis (PCA) was used to
  determine probable relationships among the
  parameters.
• Resulting factor scores were used as input for
  clustering analyses to identify stream groupings
  and compare resulting spatial differences to
  ecoregions.

Analyses
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Resulting Dataset

• May 1999 June 2002
• 94 streams, 522 records, taken at base flow
• TN 5 20410 ?g/l Median 1180 ?g/l
• TP 2.5 1320 ?g/l Median 86 ?g/l
• Chlorophyll a 0.5 216 ?g/l Median 4 ?g/l

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PCA Analysis

• Factor 1 TP, PO4-P
• Factor 2 TN, NO3-N
• Factor 3 chlorophyll a, phaeophytin a
• Factor 4 pH, DO
• Factor 5 conductivity
• Factor 6 NH4-N

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K-means Cluster Analysis

• Calculated medians of the 6 PCA factor scores for
  each of the 94 sites.
• K-means cluster analysis on all PCA factors
  resulted in 6 clusters.
• K-means cluster analysis on just the nutrient
  factors resulted in 6 clusters.

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Clustering on All Factors
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Clustering on Nutrient Factors
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N P Factors
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N P Factors
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N P Factors
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N P Factors
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N P Factors
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N P Factors
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N P Factors
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Conclusions

• Nutrient levels varied by ecoregion.
• Streams that we clustered by nutrient factors and
  independently of ecoregion showed ecoregional
  affiliations.

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Future Study

• Seasonal influences
• Chlorophyll a
• USEPA Region7 Nutrient RTAG
• Macroinvertebrates
• Watershed and land use