(Olympia, WA)  --  Washington state transportation officials say they're no longer getting help from prison inmates to pick up trash along the state's highways.  Officials tell KIRO-TV the partnership between the Department of Transportation and the Washington State Department of Corrections was put on hold last August because of concerns over how pending legislation in Olympia will impact liability.  A bill to resolve the liability issue is currently before a legislative committee.  The transportation department says Washington's growing population is contributing to the increased amount of litter on the highways.