The Watertown Area YMCA will be hosting the Riverfest 5K and 1 mile Kids Fun Run which will begin and end at Riverside Park. Not long ago, the Watertown Riverfest 5K was the only organized run in town. With a great increase in interest and dedication to fitness in the Watertown area in recent years that's no longer the case--but it is still one of the area's most popular 5K runs. The 5K is great for competitive and non-competitive runners and walkers. The one mile Kids Fun Run will begin at 8:00 a.m. and the 5k will begin at 8:30 a.m.