If your concern is data accuracy I'd just quit watering and let the lawn go to hell. That way the data will reflect the negative externalities of the decisions we make on a regular basis (such as needing to have a nice lawn). We can't have our cake and eat it too.
I don't have a lawn. My water use is less than 30% of the average use in my area. I will not cut back further to subsidize my neighbor's lack of conservation.
Lawn, yard, whatever. That's semantics. It's a half acre of whatever. You're trying to get 13,000+ gallons of crystal clear potable water onto it (and further wasting a ton in the process through evaporation as evident by the significant temperature drop). All because you want your shrubs to look nice and climate change is going to make that a non-starter. I guess you want a pat on the back for doing 30% better than horrible people. Congrats?
You are right. Life is a series of compromises. All too often we (myself included) choose ignorance over action because action requires selflessness and we have been programmed against that. Just saw some irony there in the concern over your precious data, which wouldn't accurately reflect the changing climate, which is directly related to waste, which is directly related to the choices and compromises we do or don't make.
In any event. If you don't want to xeriscape (too a greater extent than maybe you are), consider spending a whole Saturday that month you need to water walking around with your hose and flood irrigating (no nozzle), applying the water directly to the soil in lieu of applying it in the least efficient way possible (spraying it willy-nilly through the air). It will be good exercise, and you will have plenty of time to commune with each endangered native shrub and ponder the nature of life's decisions. There will still be a perceptible change in your data, but maybe it won't be so severe that you get dumped off of the website for the day.
Sorry for the preaching.