A bill to amend the River and Harbor Act of 1970 relating to the demonstration program for winter navigation of the Great Lakes-Saint Lawrence Seaway System.

Expands environmental and ecological investigations carried out to the River and Harbor Act of 1970 to include an investigation of measures necessary to ameliorate any adverse impacts upon local communities. Extends the demonstration program for winter navigation of the Great Lakes-Saint Lawrence Seaway System until June 30, 1979 (presently expires December 31, 1976). Increases appropriations for such program from $9,500,000 to $15,968,000.