Applied Ecosystem Services, LLC

The Environmental Issues Doctor

Photo of Forecasting Water Quality


Estimated reading time: 1 minutes

Predicting concentrations of chemicals in surface waters is a major component of permitting decisions, from NEPA impact assessments and NPDES point source discharge to mine closure and Superfund liability bond releases. Decision delays are costly for operators, and regulators are too often sued by those claiming that decisions were based on inadequate data.

Usual approaches to forecasting chemical concentrations are to build complex numeric ecosystem models or predict concentrations of single chemicals rather than the entire set of chemicals of interest. While the usual approaches can produce results, too often that answer is incorrect. The proper approach applies statistical time series models to the set of chemicals as a complete composition. This analytical approach is called compositional data analysis (CoDA) and is slowly gaining recognition for its usefulness in addressing complex environmental data analyses. CoDA has been extensively used for about 30 years to analyze social, economic, political, and geochemical data.

This work was originally published on the Applied Ecosystem Services, LLC web site at

It is offered under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International license. In short, you may copy and redistribute the material in any medium or format as long as you credit Dr. Richard Shepard as the author. You may not use the material for commercial purposes, and you may not distribute modified versions.

Keep reading

  1. Photo of Fit Model to Data

    Fit Model to Data


    Estimated reading time: 2 minutes

    To make informed regulatory decisions it is necessary to understand differences between ecological and environmental data. Analyses of environmental data historically use models adapted from engineering models by numerical ecologists for ecological data collected by academic and research agency scientists. These numeric and statistic models require well-structured data collected to fit assumptions and requirements of the models. This works for researchers who identify a question to be answered and work forward from that to determine when, where, and how much data need collecting to answer that question.
  2. Photo of Improving the ESA

    Improving the ESA


    Estimated reading time: 1 minutes

    The United States’ Endangered Species Act (ESA) is based on societal values, not science. For practical as well as political reasons, the ESA should remain an active, Federal statute. However, many modifications can be made in the language of the ESA to greatly improve its implementation and enforcement. Some proposed changes are minor; others will have major impact on the law. My suggestion intend: To make the ESA more reasonable, effective and accepted (by the regulated public).

Contact me to avoid, or resolve, water quality issues.