Does anyone know what happened to the ESER.ORG website?
If something happened to ESER, it may be because they gave information that was sometimes years out of date. I would suggest that you learn the use of the GIS server map on the NDIC website, it is also free and usually updated to within 10 days.
Mainly North Dakota.
If you are interested in Montana, learning to use the Mt. site is worthwhile because they give the info that most people want that ND charges for, free of charge, like the full production breakdown of wells from IP.