Section 8(4)(c) in West Bengal Municipal (Building) Rules, 2007
(c)no building shall be more than 20.00 metres long alongside the river or other water fronts. There shall be a clear linear gap between the two buildings alongside the river or other water front as per following :(i)30 metres in case the river width is more than 75 metres;(ii)20 metres in case the river width is between 50 and 75 metres;(iii)15 metres in case the river width is less than 50 metres;