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Results for April sampling periods from 1987 through 1997 show that ORNL operations adversely affect the benthic macroinvertebrate communities in First Creek, Fifth Creek, and WOC (Figs. 1 through 3). The number of taxa (i.e., total taxonomic richness) and number of pollution intolerant taxa (i.e., Ephemeroptera, Plecoptera, and Trichoptera, or EPT richness) are markedly lower downstream of ORNL effluent discharges in all three streams. |
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However, there have been some changes in the macroinvertebrate community at most sites since 1986 suggesting that improvements have occurred in environmental conditions. The most significant changes have occurred in the middle reaches of WOC at WCK 3.9, most notably since 1994, and at the downstream site in Fifth Creek (FFK 0.2). |
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In lower WOC at WCK 2.3 on the other hand, there have been no persistent changes indicating that conditions have notably improved. |
| Figure 1. Mean total taxonomic richness (number of taxa/sample) and taxonomic richness of pollution intolerant taxa (number of Ephemeroptera, Plecoptera, and Trichoptera (EPT)/sample) of the benthic macroinvertebrate community in First Creek for April sampling periods in 1987 - 1997. FCK = First Creek kilometer. |
| Figure 2. Mean total taxonomic richness (number of taxa/sample) and taxonomic richness of pollution intolerant taxa (number of Ephemeroptera, Plecoptera, and Trichoptera (EPT)/sample) of the benthic macroinvertebrate community in Fifth Creek for April sampling periods in 1987 - 1997. FFK = Fifth Creek kilometer. |
| Figure 3. Mean total taxonomic richness (number of taxa/sample)and taxonomic richness of pollution intolerant taxa (number of Ephemeroptera, Plecoptera, and Trichoptera (EPT)/sample) of the benthic macroinvertebrate community in White Oak Creek for April sampling periods in 1987-1997. WCK = White Oak Creek kilometer. |
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Last Modified: April 17, 2001