Salmon won't be up there on opening day. You might see the odd bright salmon there by July 1st.
As for trout you will probably only catch small river trout in that area. Most big trout have fallen back way down to the tidal areas for the winter and are feeding. Getting ready for the run to start up by the end of May. You might see some nice big trout up by the Rt 123 bridge by Father's day in June. Possibly the first of June.
Hey tiller, The long weekend in May is usually a good time to start fishing the Cains near route 123 for trout (and this maybe a little early as well), but as salmon fever said, unlikely for brights as the Cains tends to have a late run. hope this helps, M