PARENT SESSION
Oral Session 12: Restoration Ecology I: Streams and Wetlands.
Presiding: M Wu
Monday, August 2, 8:00 AM to 11:30 AM, Meeting Room D 133.
Current reports overestimate the ecological health of the nation's aquatic ecosystems.
HAWKINS, CHARLES*,1, 1 Utah State University, Logan, UT
ABSTRACT- Since 1972, the Clean Water Act has required states to monitor, assess, and restore the physical, chemical, and biological integrity of the Nation's surface waters. Every two years, states are required to provide the EPA with reports that describe the condition of waters within their borders, which EPA then compiles and publishes (305b reports). Biological condition is typically measured with one or more indices, whose values are interpreted as either supporting, partially supporting, or not-supporting aquatic life designated use. Although most indices have no direct biological interpretation, their values are assumed to provide a robust indication of overall biological integrity. I assessed the condition of samples taken from streams in several states by estimating the proportion of taxa in each sample that was observed relative to that expected under reference conditions (O/E varies from 0 to 1). I then determined the O/E threshold value needed to partition the population of assessed samples into the same percentages of supporting and non-supporting stream lengths reported by each state. This value varied among states, but was often as low as 0.1 to 0.2, implying that 80-90 percent of the taxa could be missing from a sample before a stream reach was declared biologically impaired (i.e., not-supporting an aquatic life designated use). Although states have recently made marked progress in developing tools for measuring the biological condition of aquatic ecosystems, the interpretation of index values may grossly overestimate the real biological condition of the nation's aquatic ecosystems. Society must balance political and economic constraints both when establishing standards to protect biological integrity and when setting restoration targets, but any meaningful balance is impossible unless we interpret indices in meaningful terms.
Key words: biological integrity, policy, environmental protection, surface water quality