Shannon Chapin, left, records notes from surveying a dam Wednesday with Steve Knapp at an impoundment on Vaughan Stream in Hallowell.  The Kleinschmidt Associates employees are locating and assessing  dams across Maine for the National Marine Fisheries Service to locate barriers to fish passage for native species, according to a statement from the federal agency.  The inventory on approximately 394 dams in the state performed by the crew consists of locating a structure across a waterway, assessing the condition and determining the current use.