Two years ago, while establishing in Cuba the National Council for Hydrological Basins, a new style emerged in environmental working efforts. Eight main basins were selected and studied distributed among eleven provinces. In this areas live 40% of the total Cuban population, and takes place 60% of national economic activity. The evaluations pointed out the main environmental problems present in these areas and contributed to the outlining of specific mitigation plans for each of them. There have been advances in reforestation, elimination or reduction of important contaminating sources, in environmental education, as well as the sanitary conditions in human habitats. In 1999 twenty new basins -at a provincial scale- were studied.

Over the last decade eutrophication of freshwater artificial reservoirs in Cuba occurred in parallel to oligotrophication of estuarine and coastal waters. These two processes influenced both freshwater and marine fisheries. A dramatic shift in species composition in freshwater fisheries has occurred, from dominance by cichlids (tilapia) to dominance by cyprinids. The high fishery yield from some reservoirs, and shift in species composition, seems related to progressive eutrophication of reservoirs by nutrient subsidies from different anthropogenic activities; particular those related to the size of urban areas within their watersheds.

Rivers and Lakes Of Cuba’s 200 rivers, only 2 are navigable. The Cauto, located in the southeast and 240 km (150 mi) long, provides only 120 km (75 mi) of transport waterway. The Sagua la Grande, in central Cuba, is large enough to provide hydroelectric power and is navigable for short stretches. Several waterfalls throughout the island provide small amounts of hydroelectric power. The rest of the rivers are small and shallow, but several are internationally known for their trophy-sized fish.