New Jersey wants another year to decide one of its most intractable environmental issues: whether to allow experimental oyster colonies in polluted areas to see if they can help clean the waterways. The research is designed to see if re-establishing oysters in areas like the Raritan Bay can help improve water quality by using their natural filtering techniques. Environmentalists and scientists began planting oyster colonies in polluted areas including Raritan Bay in the early 2000s, hoping to re-establish a species that was once so plentiful that maritime charts listed piles of oysters as threats to navigation. Researchers now want to expand the oyster colonies to other parts of the bay and to other waterways in the state to see once and for all if the shellfish can improve water quality.