Which other municipalities/utilities irrigate their lawns with treated wastewater effluent?
The Pebble Beach golf course in California near Carmel and Monterey on the Monterey Peninsula uses treated waste water to irrigate their greens. Parsons Engineering Science Inc. of Alameda, California designed their treatment facilities. The project is financed by 4 entities: the Carmel Area Wastewater District (CAWD), Pebble Beach Community Services District (PBCSD), Monterey Peninsula Water Management District (MPWMD), and the privately-owned Pebble Beach Company (PBC). See article by Ian Lisk at http://www.wwdmag.com/wastewater/tertiary-treated-wastewater-irrigates-monterey-peninsulas-recreational-acreage
There is some concern about contaminant accumulation in reclaimed water. In Montana reuse is regulated by our Department of Environmental Quality. Perhaps your state's department can supply you with a guideline to refer to?
Risk to human health and exposure is the primary risk. Pathogens such as viruses, bacteria, nematodes, helminths, worms etc. Depending on the reuse application, there are different treatment requirements as well as requirements to limit exposure to irrigated lands. i.e. fencing, night time irrigation etc.
The City of Vernon, BC has used tertiary level treated effluent for years.
California had the most stringent effluent requirements, Code Title 22 Recycled Water Regulations when I was last looking into this. California are certainly leaders in regulating and implementing re-use of treated effluent.