A vessel's draft is another obstacle to passage on the seaway, particularly in connecting waterways such as the Saint Lawrence River. The depth in the seaway's channels is (Panamax-depth) downstream of Quebec City, between Quebec City and Deschaillons, to Montreal, and upstream of Montreal. Channel depths and limited lock sizes meant only 10% of current oceangoing ships, which have been built much larger than in the 1950s, can traverse the entire seaway. Proposals to expand the seaway, dating from as early as the 1960s, have been rejected since the late 20th century as too costly. In addition, researchers, policy makers, and the public are much more aware of the environmental issues that have accompanied seaway development and are reluctant to open the Great Lakes to more invasions of damaging species, as well as associated issues along the canals and river. Questions have been raised as to whether such infrastructure costs could ever be recovered. Lower water levels in the Great Lakes have also posed problems for some vessels in recent years, and pose greater issues to communities, industries, and agriculture in the region.