Williams Creek is a fantastic river in Terrace that serves as the local after work classic when you want to go river running. Located just a few minutes from the center of town, this river flows out of the mountains into the Skeena, carving a beautiful valley through coastal forest with smooth granite and clear water of exceedingly high quality. Aside from being the bread and butter run for the locals, and it's a must do for anyone who's in that zone when the water is flowing.
Generally speaking, most of the rivers close to Terrace flow best from snowmelt in the spring and early summer, and Williams is no exception. Unless there's a ton of snow, July is usually getting pretty late to catch it with water. It will also run from rain throughout the year, but the northerly location tends to shut it down for the winter even though Terrace is close to the coast. There is a visual gauge at the take out. 0.3 to 0.5 is a a good low through high range preferred by the local crowd.
Williams is found south of Terrace, about 10 minutes from town. The take out is at a bridge over the river on Old Lakelse Lake Drive, which intersects with highway 16 east of Terrace. Follow this road south for about 12 km until it crosses the river. There's a large parking area on river left downstream of the bridge. The put in is up the river right logging road. The most obvious put in (Middle Williams) is at a bridge over the river, found down a short spur off the logging main about 7 km in. There is a short section above this called the Race Course, accessed by going about 1 km further upstream where there is a good but hard to find trail right off the road down to the water. There is also river access at the start and the end of the significant whitewater, letting you customize your Williams experience depending on the group and water level.
At the Race Course put in, the river is mellow, but quickly picks up to fun class III-IV read and run down to and past the road bridge put in. It mellows for a while below here until you get to the first rapid, a small ledge called Toothache that has a big hole at high flow. Ledges of smooth granite and long boulder slaloms come in quick succession after here for a few km through the meat of the run, with most places having relatively easy scouting and portaging. After the last rapids, it takes around half an hour to paddle all the way out to the road.