The U.S. Army Corps of Engineers has "made good progress" in broadening a study of possible navigation improvements on the Upper Mississippi River-Illinois Waterway system to give greater consideration to ecological restoration, says a new report from the National Academies' National Research Council. However, because of flaws in the models used in the study to predict demand for barge transportation, the economic justification for expanding locks on the rivers has not yet been demonstrated, the report says. And little attention has been paid to inexpensive, nonstructural navigation improvements that could ease current barge traffic. "The Corps should be commended for expanding the scope of its study, but changes are still needed to make the study fully credible," said John J.