Article 78 proceeding to determine validity of unpaid water and sewar charges  assessed against real property by City of New York Department of Environment Protection dismissed. Petitioner objected to the water and sewar charges and subsequently entered into a settlement agreement with the City agency. After petitioner performed the settlement agreement by paying stipulated amounts, the City demanded payment of the balance of charges. Court held the Department of Environment Protection had no authority to enter into an accord and satisfaction of the charges.