Surface water

The Parker River basin, which has an area of about 66 mi2 in northeastern Massachusetts, contains numerous small streams that wind through extensive wetlands. It is bordered on the south by basins of the Rowley River and a few smaller coastal streams, which together drain about 15 mi2 and are discussed with the Parker River in this report. Upstream of coastal tidal marshes, about 70 percent of these basins is forested and about 15 percent is covered by lakes, ponds, and marshes. There are a total of 18 lakes and ponds, 10 of which cover at least 10 acres. The largest lake is Pentucket Pond in Georgetown, which is 85 acres.

Wetlands upstream from Byfield and the tidal estuary downstream from Byfield minimize flood flows caused by storms by temporarily storing surface water in low areas and in wetland sediments. However, because wetlands transpire and evaporate large amounts of water, low flows can be depressed downstream from wetlands during the late spring to early fall growing season.

As is common in areas containing many wetlands, stream gradients are low. For example, the channel slope from the headwaters area of the Parker River to the USGS streamflow-gaging station at Byfield, a distance of about 11 river mi, is about 6 ft/mi.

About one-third of the runoff from the Parker River basin is measured at the Byfield streamflow-gaging station; the remainder enters the river channel in the tidal reach below Byfield or flows directly into tidal marshes and Plum Island Sound.