Water Quality Assessment and Onshore Development in Tropical Waters

Standards for bacteriological recreational water quality in Puerto Rico are those proposed by US EPA. The standard for primary contact recreational use has both single-sample limits and running- average threshold limits based on historical data developed for the specific site. La Parguera is the site of a Special Marine Reserve and counts among its unusual habitats a phosphorescent bay, important reef systems and a diverse and healthy mangrove system including significant cays.A study, underway since 1998, has analyzed inshore waters for total coliforms (TC), fecal coliforms (FC), Escherichia coli (Ec) and Enterococcus (Ent) in addition to some twenty-odd other chemical, biological and physical parameters. In support of this effort mapping activities, including surveys and development of a map including heavy development occurring in the last four years, are underway. A number of stations, selected for the onshore development and natural systems located onshore, were monitored over the period. Significant differences were found among stations monitored in the frequency of violations of Ent standards for primary contact activities. In addition, several of the chemical and physical parameters monitored showed significant differences between stations. Those stations and the incidence of violations are correlated to onshore land use and the parameters monitored during the study. The development and utility of the map for the study, the classification of onshore development and planned experiments to measure ameliorative efforts are discussed. Categorization by level of development onshore, supported by watershed modeling and close study of risks, is useful in predicting the occurrence of high indicator densities in these waters.