Christine,
Thanks for taking the time to respond. After a couple of weeks of learning ArcHydro I was able to get the problem solved. I modified one of the models in the ArcHydro toolbox to create the features you mentioned. Then all I had to do was run Populate DrainArea for Drainage Lines under Attribute Tools. I wasn't able that particular tool in the ArcHydro toolbox so I couldn't include it in the model.
Below is a screenshot of the modified model if anyone is interested. Because I have to run this on 82 counties I included the target locations as parameters/variables so it was easy to deploy. It runs pretty seamlessly. I've only had it crash a couple of times and I'm using 2GB+ LIDAR derived county DEMs.
Initially I kept getting the COM Return error, but after upgrading to 2.1 and ArcMap 10.2 it has been smooth sailing.
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