During the Valley secession campaign in 2002, the city's Department of Water and Power hid its plans to ask for massive rate hikes, the Daily News charges in its lead story today. Fear of big utility rate increases under a new city was one of the main arguments used against secession in the Valley. Residents of the Valley are especially sensitive to DWP rates because they use more electricity and water to keep cool and maintain their lawns and yards during the hot summers.