Establishing Reference Expectations Using Data Collected with Different Sampling Protocols

Ellen Natesan 1 and Lester L. Yuan 2

1 American Association for the Advancement of Science Environmental Fellow
2 National Center for Environmental Assessment, Office of Research and Development, US Environmental Protection Agency, Washington, DC 20460

The goal of the National Wadeable Streams Survey Demonstration is to characterize the ecological condition of wadeable streams in the United States. EMAP monitoring protocols will be used to collect data from streams in EPA Regions 1 through 7 and combined with previously collected data from Regions 8 through 10 to derive a national assessment of streams. Biological condition will be inferred using a variety of commonly used metrics (e.g. Ephemeroptera, Plecoptera and Trichoptera richness) that are known to respond to anthropogenic disturbance. However, to be most informative these metric values must be compared to expectations that are established by a set of least-impacted reference sites. At the present time, only limited sampling of reference sites in Regions 1 through 7 is planned. However, these reference sites can be characterized more completely if existing state, USGS and historic data can be incorporated. These data have been collected using sampling protocols that differ from the current EMAP protocol, which hampers efforts to combine the data in a single analysis. We present a potential method for reconciling biological data collected using different protocols. We illustrate this method using a pilot study, in which existing state data from EPA Region 3 is used to derive reference expectations. These reference expectations are then compared to expectations derived using data collected using EMAP protocols.

Keywords: reference condition, sampling protocols, national stream survey