Consider including 5_data_munge/out/wqp_daily_depths.rds into final data

[limnoliver]

Right now these data are not included in the final combined dataset. I don't totally recall why, but I think it was related to some of the records potentially being lake sites, or not knowing how we should handle multiple depths. One thing we could consider is to treat a depth as a "sub_location", similar to how sensors at different depths are handled in NWIS.