Origins of stream salinization in an upland New England watershed

Salinity levels are above historical levels in many New England watersheds. We investigated potential sources of salinity in the Pemigewasset River, a relatively undeveloped watershed in northern New England. We utilized a synoptic sampling approach on six occasions between April and September 2011 paired with a novel land use analysis that incorporated traditional watershed and riparian zones as well as a local contributing area. We established background specific conductivity (SC) and found that SC was above established background levels in both the mainstem of the river (peak of 172 μS cm⁻¹) and multiple tributaries. Specific conductivity was highest during low flow conditions (June) indicating potential groundwater storage and release of de-icing salts applied during winter months. Development in the watershed and riparian zone was found to be more strongly associated with elevated SC, compared to roads. The local contributing area was not found to be strongly associated with SC; however, there was evidence that the local contributing area may contribute to SC under low flow conditions.