The Marshfield Waterways Committee this month plans to settle on a list of topics that it will address over the course of 2013 to develop a waterways plan, according to Michael McNamara, committee chairman. McNamara declined to discuss the committee’s priorities, which it refined after public hearings, but according to minutes from the Dec. 5 meeting, one person suggested that rivers and ponds be included to the extent that pollution from those waters affects navigable waters. Another person asked that the town study the maximum sustainable yield of the shellfish harvest, and another asked for a survey of town docks. McNamara said the committee hopes to make recommendations to the Board of Selectmen in late spring, and that the plan should be complete in late 2013 or early 2014. The Urban Harbors Institute at the University of Massachusetts Boston is consulting on the project.