Assessing coastal waters of American Samoa: territory-wide water quality data provide a critical big-picture view for this tropical archipelago

The coastal waters of American Samoa's five high islands (Tutuila, Aunu'u, Ofu, Olosega, and Ta'u) were surveyed in 2004 using a probabilistic design. Water quality data were collected from the near-shore coastal habitat, defined as all near-shore coastal waters including embayments, extending out to 1/4 mile off-shore. Hydrography and water column samples were collected, and water quality data were compared to the Territorial water quality standards for pH, dissolved oxygen (DO), Enterococcus, chlorophyll a, water clarity, total nitrogen, and total phosphorus. All station measurements for pH, DO, and Enterococcus satisfied the local water quality standards, although some fraction of the Territory could not be assessed for either DO or Enterococcus. With respect to chlorophyll a, 66 +/- 18% of Territory coastal waters complied with the standard, while 34 +/- 18% failed to comply with the standard. For water clarity, 54 +/- 18% of the Territorial waters complied with the standard while 42 +/- 7% failed to comply. Territorial waters satisfied the standards for total nitrogen and phosphorus 72 +/- 17% and 92 +/- 10%, respectively. These data provide the first big-picture view of water quality in the near shore region around the high islands of American Samoa. While the picture is encouraging, these data suggest emerging water quality concerns.