It took years of effort and investment to bring migratory fish back to the Presumpscot River as it flows through Westbrook. Now experts and advocates will have to wait to see what impact a landslide that blocked the river this week has on fish migration patterns and the river’s health. Sea-run fish won’t migrate upriver until spring, and advocates hope that will allow enough time to restore the river and allow clear passage. And the impact on the health of other aquatic live could depend on how much of the sediment is removed and how much is left to blanket the riverbed downstream.PORTLAND PRESS HERALD • September 18, 2020