The Metals Tolerance Index is a diagnostic metric used to identify samples with a high degree of organisms tolerant of metals. This index is on a scale from 0 to 10 with higher values indicating more tolerant organism, and more polluted conditions. The formula is ∑ (RAi * ti ), where RAi is the fraction or relative abundance of individuals of the "i"th taxon in the sample, ti is the tolerance index value of that taxon.
McGuire, D. L. 2009. Clarke Fork River Biomonitoring Macroinvertebrate Community Assessments in 2008. McGuire Consulting Prepared for CH2MHill and submitted to US Environmental Protection Agency Region 8, Boise, Idaho.
If the organism you need is missing, first make sure the above is not checked. If you still cannot find it, contact Doug Henderson (Douglas.Henderson@KingCounty.gov) with its name, its parent taxon, e.g., a species's genus, and, if available, its TSN.