Three of the most important rivers in the Philippines are at risk from water depletion due to illegal conversion of their common watershed into cabbage farms, officials said Monday.

Provincial Governor Maximo Dalog said the local administration had asked the national government to cancel land titles covering forested sections of the affected area, the Mount Data National Park.

The 5,512-hectare (13,620-acre) park in the Cordillera range is the common watershed of the Chico, Amburayan and Agno rivers, which provide irrigation, tap water and electricity to the northern Philippines.

Forest rangers are powerless to stop the deforestation because the culprits are armed with land titles issued by the environment and natural resources department, provincial government spokesman Andrew Doga-ong told reporters.

The provincial government estimates only 33 percent of the park still has forest cover.

Declared a protected area by a 1963 law which allowed only 349 hectares to be converted to other uses, some 2,902 hectares of forests have been cut down and the land turned into vegetable farms and residential areas.

The park is under renewed siege as farmers burn the Dacudac section of the watershed to expand plots planted with cabbage, potatoes and carrots, said Febe Sally, a local vice mayor.