Rafters, anglers and swimmers beware: The Pit River, which flows from Eastern Shasta County to Lake Shasta, will grow by more than three times it’s size this weekend on a 9 mile stretch between Pit 5 Dam and Big Bend. As part of their licensing conditions for operating hydroelectric plants along the Pit River, PG&E is required to provide whitewater flows periodically to replicate the inconsistency the river would have if it weren’t dammed. Friday the current flow of about 450 cubic feet per second will increase to 1,500 CFS. It’ll then gradually recede to 450 CFS Sunday afternoon. PG&E says the flush will create class 4 and 5 rapids that are appropriate only for skilled paddlers. This year’s heavy rains and the continually melting record snowpack have already swelled the river and its tributaries, including Fall River and Hat Creek, above the seasonal norm.