You can not load the data without having loaded the header, hence it can be assumed that ReadHeader(IDiagnostics) has already been called.
public void ReadData(
IDiagnostics diagnostics
)[Missing <param name="diagnostics"/> documentation for "M:DHI.Mike1D.ResultDataAccess.Epanet.MuEpanetBridge.ReadData(DHI.Mike1D.Generic.IDiagnostics)"]