one city on the front range that isn't even in the colorado river watershed is hardly indicative of the snow pack / snowfall inside that watershed. The inflows into lake Powell are a much better equivalent for the entire watershed and do show a decline. https://graphs.water-data.com/lakepowell/ though that doesn't show diversions / how much is being caught in upstream reservoirs. and the snotel graphs for the watersheds in the colorado basin are a much better source https://www.wcc.nrcs.usda.gov/ftpref/support/states/CO/produ...
I chose Boulder as it has very good record keeping(and it goes way back) and is a good bellwether for the state, plus a number of key government climate labs are based here. So its a solid data point. If I had more time I would crunch numbers from a array of other cities like Breckenridge, Aspen, Colorado springs, and Grand Junction, the former two may or may not have great data from before the 1950s'.
