Filling gaps in your data

After mosaicing all the Travis county DEMs (10meter) you can see the abrupt white squiggles that represent areas that have NoData.

After running this through the Raster Calculator using the conditional formula FilledDEM= Con (isnull([traviscty]),Focalmean([traviscty],rectangle,4,4),[traviscty])  through several iterations, the result was a gapless digital elevation model for all of Travis county.