[jvanderbot]

That's very interesting. It should be pointed out that all of NASAs data is open (by law - source I used to work there, subject to a short embargo for phds to be written). So anyone could have the same data underneath. But this analysis is cool.

So, the questions that remain:

1. Are lawns more or less likely to be treated with chemicals that harm waterways

2. Are lawns more or less likely to produce runoff of those treatments

3. Given answers to above is the net effect more or less than agriculture on our water.

I'm not seeing much that answers those questions specifically. It does appear there's regulations against phosphorous lawn fertilizer nowadays. But that's all I can find on a cursory search. I'm happy to believe they both are equally important nowadays.

[ttyprintk]

Those would be valuable to know, but I bet separating the non-point-sources is unachievable. I mean, we may be detecting latent (> 1 year old) hydrological concentrations from the combination of lawn, ag, failing septic tanks, and point sources that conveniently become non-point.

On that last source: the design is to concentrate liquid manure, which as a point source is a liability, and spray it over an area. I believe this makes it a non-point-source for the purposes of carveouts in the clean water act.