Fans of cleaner rivers and the Chesapeake Bay are claiming victory with the passage in the General Assembly of a significant environmental bill. The legislation will require thousands of Maryland homes to install more costly nitrogen-removing septic systems. Opponents say the cost of the systems will hurt a housing industry that’s already suffering and also be a burden to those living in rural areas. Senate President Thomas V. Mike Miller made passage of the bill a priority, saying the clarity of the bay’s water is not what it was when he was a child.