In a novel way to check factories from flushing waste into a river, it has now been made mandatory for industrial units in the Baddi and Barotiwala industrial towns of Himachal Pradesh to build fish ponds. The treated waste water flowing out from each factory in these towns will now have to flow into a fish pond. And only if fish survive in that water will it be allowed to flow into the nearby Sarsa river. The State Pollution Control Board has decided to get tough with industrialists who have been accused of allowing untreated factory waste into the Sarsa river, often killing fish and other marine life in it.