Introduction

An important element required for survival of all species-water is available mainly as Surface Water and Ground Water. Our state is blessed with one of the major river systems of India comprising three major river valleys viz. Godavari, Krishna and Pennar and about 37 medium and minor river systems which carry about 38.45 million hectare meters of water into the Bay of Bengal. The drainage area of the rivers Krishna and Godavari within the state is 1,47,722 sq. km, which is nearly 64% of the geographical area of the state. Andhra Pradesh comprises several major and minor lake systems, important being the Kolleru lake, which is identified as the largest fresh water lake system in Asia. Lake Pulicat is one of the major salt-water lakes in our state. This lake is located in Nellore district.