Why is a plan required to bring back the alewife?

Most of the alewife’s upstream spawning habitat has been closed to them since 1987, when alewife were believed to have caused a rapid decline in the smallmouth bass population. Maine State law closed passage at all but the most downstream dam (Milltown) in 1995. That law was amended in 2008 to reopen the next dam upstream (Woodland), but alewife can still only access 2% of their native habitat in the basin.