A new federal report lists one-third of Iowa’s waterways as “impaired.” Susan Heathcote of the Iowa Environmental Council says most of the pollution comes from run-off — dirt or chemicals applied to land which are pushed into rivers and lakes by rain.Heathcote says the report isn’t all bad news, as Iowa has made progress in cutting back pollution from factories.Heathcote says you should swim and fish with caution in the one-third of Iowa lakes, rivers and streams which are classified by the E-P-A as impaired. Heathcote says a few of those streams are in such poor shape that fish can’t live in the waterway.