Feildes Weir is a weir on the River Lea located near Hoddesdon, Hertfordshire at the confluence of the River Lea and River Stort. The weir marks the start of the Lower Lee. A channel of the man-made River Lee Flood Relief Channel is incorporated into the weir.
In 1976 a 29 metre wide thin-plate weir was installed, with three vertical-lift sluices controlling a parallel flood relief channel. Flows average about 4.4 m3/s discharge over the weir; higher flows enter the flood channel .