@tconz That's a good question. In another aspect of my life, one of my tasks is helping people to understand chemical analysis reports. I find this article helpful in explaining how colony counts are done:
http://microbiologynetwork.com/counting-colonies.asp
What is the bottom line? M. chimaera was detected in your water - at the lowest measurable level. I don't know if this is a level of concern as far as danger of infection. It is helpful to know there are no other NTM detected. One way to limit/eliminate NTM in your water is to turn your water heater to 135F or hotter.

I see that you are also on ntminfo.org. Perhaps you can address Dr Joe Falkinham there and ask for his input?
Sue