DWQ-2011-020001

FIGURE 1: Taxa richness is a tally of how many different kinds of organisms are present.
It’s a good metric to broadly compare community diversity and structure. However, it
lacks the ability to describe the composition of the community. For example, how many
groups are pollutant-tolerant versus intolerant? Although we’d expect some diversity
reduction from upstream to downstream due to some ‘urban-effect’, the degree it
appeared in RBC was beyond that effect. For example, the Chipeta Way site is located
only 500 yards downstream of the Red Butte garden site, yet on average contains half the
number of richness through April 2011.

Update 1: The July 2011 sample reveals improvements (increases) in invertebrate
diversity in the oil-impacted site locations.

Update 2: Both oil impacted areas collected in late August reveal increases in taxa
richness; which is in addition to the increased taxa richness observed in July. Also, take
note that the taxa richness at the Chipeta Way site surpassed taxa richness observed
upstream (RB Garden).
Taxa Richness
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Jun-10 Aug-10 Nov-10 April-2011 July-11 Aug-11
Sample Date
Above Spill (RB Garden)
Below Spill (Chipeta Way)
Below Spill (1500 East)

FIGURE 2: This measure is tallying how many aquatic organisms were collected. Note
the improvement in the Chipeta Way site since November 2010 while the 1500 E (Miller
Park) location continues to be very reduced. Bear in mind that the individuals counted in
the Chipeta Way location predominately consist of three taxa (mayfly, blackfly, and
midge) which comprise 97% of the sample compared to 79% above the spill. In other
words, this location is improving in overall numbers, however the diversity in the
community is relatively homogenous.

Update 1: The most dramatic improvements to the overall number of aquatic organisms
for the July 2011 sample was found at the 1500 East location.

Update 2: The total number of aquatic organisms remained relatively unchanged.
However, as the Figure 1 indicated, the community composition has changed.
Number of Aquatic Organisms
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Jun-10 Aug-10 Nov-10 Apr-11 July-11 Aug-11
Sample Date
Above Spill (RB Garden)
Below Spill (Chipeta Way)
Below Spill (1500 East)

Figure 3: EPT Taxa Richness is a tally of how many (E)phemeroptera, (P)lecoptera, and
(T)richoptera groups were collected. Ephemeroptera (mayflies), Plecoptera (stoneflies),
and Trichoptera (caddisflies) groups are generally more sensitive to various types of
pollutants and other changes to their environment. This measure provides a better
understanding of the community composition at each site. Notice that many of the more
sensitive taxa (groups) have not recovered in locations affected by the oil spill.

Update 1: The July 2011 sample estimates that EPT diversity at the Chipeta Way location
nearly tripled since April 2011. Additionally, the 1500 East location adds another EPT
taxon.

Update 2: As Figure 1 indicated, there are observed increases in community composition.
This figure is showing that some of the increase is attributable to higher EPT taxa
richness. The most marked change was observed at the lowest sampled site where EPT
taxa richness increased over three times from the previous collection. In addition, taxa
richness at the Chipeta Way site is nearing the taxa richness above the spill (RG Garden).
EPT Taxa Richness
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Jun-10 Aug-10 Nov-10 Apr-11 July-11 Aug-11
Sample Date
Above Spill (RB Garden)
Below Spill (Chipeta Way)
Below Spill (1500 East)

Figure 4: EPT abundance is the number of individuals collected representing EPT groups.
Notice in November 2010, the Chipeta Way site begins to populate with some EPT taxa.
However, the EPT population is predominately dominated by one taxon, Baetis mayfly,
which represents 98% of EPT while only representing 68% of EPT above the spill.
Additionally, the 1500 East location has yet to establish any EPT population.

Update 1: The July 2011 sample reveals that the EPT population has increased in the oil-
impacted sites from year over year. The 1500 East location has established a Baetidae
population; while the Chipeta Way location experienced increased EPT abundance
overall. However, 92% of the Chipeta Way EPT taxa abundance is attributed to Baetidae;
whereas 63% of EPT taxa is attributed to Baetidae above the spill. This suggests the
newest EPT taxa have yet to gain a comparable population at this location.

Update 2: Reflective of Figure 2, EPT abundance has remained relatively unchanged.
However, the community composition of the Chipeta Way site shifted towards a less
dominated community of Baetidae, comprising 82%. This suggests the more recent EPT
taxa are becoming more established.

EPT Abundance
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Jun-10 Aug-10 Nov-10 Apr-11 July-11 Aug-11
Sample Date
Above Spill (RB Garden)
Below Spill (Chipeta Way)
Below Spill (1500 East)