The Rideau Valley Conservation Authority (RVCA) is an inter-municipal environmental protection and advisory agency that works with local municipalities, government agencies, special interest groups and the general public to protect the natural resources of the Rideau River watershed. The watershed drains an area of over 4,000 square kilometres of eastern Ontario and includes towns such as Portland, Perth, Smith Falls, Merrickville, Kemptville, and Manotick. About 620,000 live in the watershed, mostly deriving from the City of Ottawa. There are 18 municipalities within the valley and most people, outside of Ottawa, draw their drinking water from the river or from groundwater.