Most of WC LUT traffic is on VHF 151.055 PL100.0 repeater, but in the past weeks I have heard their talkgroups on the WC TRS come active with traffic.
I am not aware of any 800 conventional frequencies assigned to LUT, however Clean Water Services does have conventional repeaters on 856.3375MHz WNSR611. I've heard activity at the Hillsboro treatment plant and I think at the Portland and Tigard plants are also set up similarly.
For construction operations outside of the treatment plants, they use their WC TRS talkgroups.