atcUtility depends on MapWinUtility.dll, so be sure to get the version of MapWinUtility.dll that was in the same package with it.
If this is the version from BASINS, then it is compiled for x86 and .Net 3.5. If it is from D4EM, then it is compiled for x86 and .Net 4.0.
If this is the version from BASINS, then it is compiled for x86 and .Net 3.5. If it is from D4EM, then it is compiled for x86 and .Net 4.0.