I've mentioned "tolerance values" for taxa in many blog entries. Where do we find them?
For the tolerance values -- by family -- used by StreamWatch and VA DEQ, go to the StreamWatch website at:
For tolerance values by genus, as determined by region of the country, I have used "Appendix B: Regional Tolerance Values, Functional Feeding Groups and Habit-Behavior Assignments for Benthic Macroinvertebrates," which is part of the EPA's Rapid Bioassessment Protocols for Use in Stream and Wadeable Rivers: Periphyton, Benthic Macroinvertebrates, and Fish: Second Edition. This is available on line at:
The "regional tolerance values" I've followed are those posted for the "southeast" -- specifically North Carolina.
Please note that all of these values are up for debate and must be considered tentative. Also, Virginia DEQ is presently developing its own scale of tolerance values by genus and will start using those assessments this year.
(Please see the entry for 6/14 for an update on North Carolina tolerance values.)