An estuary is a coastal area where a river meets the sea, creating an unique ecosystem for fresh water as well as marine species. This is the only tropical estuary included in the U.S. Environmental Protection Agency National Estuary Program, and its home to 124 species of fish, 160 species of birds and 19 species of reptiles and amphibians.
Around 1920, urban developers began filling up the margins of the Caño with concrete, to start building affordable houses, in its majority for families who migrated to San Juan in search of better opportunities. Nowadays, "the 70 percent of the river basin is developed and the waterproofing of the land with concrete facilitates and accelerates the transport of polluting agents." "In spite of its great natural, economic and social value, few have realized that the future of this valuable coastal ecosystem depends on the actions taken in the municipalities that compose its hydrographic river basin", as well as the communities that surround the Caño. In addition, poor planning, sedimentation and contamination, have contributed to the environmental deterioration of the estuary and to the socioeconomic marginalization of the communities that surround it.
As part of the revamping plan for the estuary, dredging of the Caño is set to start before 2012; a modern sanitary sewage system will be constructed. Reforestation of the banks of the rivers that feed the estuary is key to restrain the passage of pollutants and prevent sedimentation. Another priority of this initiative is to establish biological indicators that allow the evaluation of the quality of the waters of the estuary. This phase will happen with the collaboration of the University of Puerto Rico-Mayagüez and a group of volunteers that will take and analyze the samples, to create a database.”
The revitalization of the San Juan Bay Estuary "is part of the mission of the Enlace Project, a multi-sectorial effort to promote socio-economical and environmental justice for the communities bordering the Caño." This communitarian group has participated in the formulation of Integral Plan of Handling and Conservation of the San Juan Bay Estuary, organizes outreach activities to educate the population, contractors and the government on the problems that affect the zone, and proposed the Land Trust, that gives collective ownership of the land to the residents of the Caño.