Agricultural activities in Tonga are exhausting the fertility of the soil. The forest area is declining because of land clearing, and attempts at reforestation have had limited success. Water pollution is also a significant problem due to salinization, sewage, and toxic chemicals from farming activities. The impurity of the water supply contributes to the spread of disease. The nation is also vulnerable to cyclones, flooding, earthquakes, and drought. The government has established a Water Master Plan to manage the nation's water resources for two decades. The National Development Plan is a more comprehensive attempt to address the nation's environmental concerns.
There has been some damage to the nation's coral reefs from starfish and from coral and shell collectors. The Fiji banded iguana, and the loggerhead, green sea, and hawksbill turtles are endangered. Overhunting threatens the native sea turtle populations. The Tonga ground skink has become extinct.