Alabama estuaries cover an area of 610 square miles, including Mobile Bay, the fourth largest estuary on the North American continent. Mobile Bay drains a watershed of approximately 43,662 square miles, receiving an average of 460,000 gallons per second of freshwater.
The U.S. EPA’s National Coastal Condition Assessment (NCCA) is a multi-year partnership with the EPA’s Office of Research and Development (ORD), EPA’s Regional office, all coastal states, and selected territories and tribes. Alabama entered the program in 2000 and continues to participate in each event. Samples are collected to determine water quality, sediment quality, and biota at each location. ADEM partners with the Alabama Department of Natural Resources, Marine Resources Division (AMRD) for collection of fish tissue. NCCA initially started as an annual program and has now shifted to once every five years. The NCCA program is based on EPA’s Environmental Monitoring and Assessment Program (EMAP), using a compatible probabilistic program and a common set of environmental indicators to survey each state’s estuaries and assess their condition. These estimates can then be aggregated to assess conditions at EPA’s regional, biogeographical, and national levels.
The goal of NCCA is to make statistically unbiased estimates of ecological condition with known confidence. To approach this goal, a probabilistic sampling framework was established among the overall estuarine areas along the Alabama coast. Under this design, each sampling point is a statistically valid probability sample. Thus, percentages of estuarine area with values of selected indicators differing from established environmental guidelines can be estimated based on the conditions observed at the individual sampling locations. Statistical confidence intervals around these estimates also can be calculated. Moreover, these estimates can be combined with estimates from other states or regions that were sampled in a consistent manner to yield national estimates of estuarine condition.
The goal of NCCA is to make statistically unbiased estimates of ecological condition with know confidence. To approach this goal, a probabilistic sampling framework was established among the overall estuarine areas along the Alabama coast. Under this design, each sampling point is a statistically valid probability sample. Thus, percentages of estuarine area with values of selected indicators differing from established environmental guidelines can be estimated based on the conditions observed at the individual sampling locations. Statistical confidence intervals around these estimates also can be calculated. Moreover, these estimates can be combined with estimates from other states or regions that were sampled in a consistent manner to yield national estimates of estuarine condition.