Chew Magna Reservoir is a small reservoir on the western outskirts of the village of Chew Magna, Somerset, England. It lies just north of the B3130 Winford Road.
This 5 acres (2 ha) reservoir was created in the 1930s, damming Winford brook, to supply water for villages in the Chew Valley. It is owned and managed by Bristol Water.
Chew Magna reservoir provides fly fishing for stocked Brown Trout (Salmo trutta morpha fario) and Rainbow Trout (Oncorhynchus mykiss). Rainbows can be fished all year. Parking is close to the lake and there are many stagings erected around the lake.
In 2011 the reservoir emptied following a long period without sustained rainfall. Staff from Bristol Water rescued the trout and transferred them to the nearby Chew Valley Lake.