You are here:
A flow-chart for developing water quality criteria from two field-based methods
Citation:
Cormier, S., L. Zheng, R. Novak, AND C. Flaherty. A flow-chart for developing water quality criteria from two field-based methods. SCIENCE OF THE TOTAL ENVIRONMENT. Elsevier BV, AMSTERDAM, Netherlands, 633:1647-1656, (2018). https://doi.org/10.1016/j.scitotenv.2018.01.137
Impact/Purpose:
This paper describes a selection process for choosing between different methods to estimate a specific conductivity level that is expected to extirpate 5% of benthic invertebrates from streams. Examples are calculated for 63 ecoregions in the conterminous United States with cautionary notes regards ecoregional background variability, ionic composition and degree an landscape modification.
Description:
We developed and then used a flowchart to identify example specific conductivity (SC) hazardous concentration (HC05) values for 63 of the 85 Level III ecoregions in the conterminous United States. Using the flowchart, we compared SC HC05 values estimated at the mean regression line and the lower 50% prediction limit of a field-based background-to-criterion (B-C) model, and where data were sufficient, we also estimated an HC05 from a field-based extirpation concentration distribution (XCD) using the method developed by the U.S. Environmental Protection Agency in 2011. The B-C model is a least squares regression of HC05 values against estimates of background SC for ion mixtures dominated by HCO3− and SO42− (mg/L). The branch points that lead to selection of an HC05 from the flowchart are determined by characteristics of data sets and confidence in estimated HC05 values. We indicated our confidence in these example SC HC05 values based on the size of the data sets and ecoregional SC disturbance. The level of ecoregional SC disturbance was judged by comparing the background SC (the 25th centile of the data set used to calculate a HC05) and an estimate of natural base flow SC modeled from geophysical attributes in the region. The B-C approach appears to be a viable option for calculating a SC benchmark with inexpensive estimates of SC background.
URLs/Downloads:
DOI: A flow-chart for developing water quality criteria from two field-based methods
FLOWCHART MAIN NIHMS-1017938.PDF (PDF, NA pp, 694.405 KB, about PDF)
NIHMS1017938-SUPPLEMENT-APPENDIX_A.PDF (PDF, NA pp, 188.458 KB, about PDF)
https://www.ncbi.nlm.nih.gov/pmc/articles/pmc7249996/