Increasingly, ecologists are being called upon to demonstrate how ecological interactions are modified by human disturbances, and what the consequences are for ecosystem services.  As a prime example, streams of the northeastern United States are experiencing increasing baseline salinities as a result of road deicer runoff.  Preliminary studies have shown increases of microbial respiration on leaf litter in response to heightened chloride levels.  Organic debris dams in streams can serve as regions of high microbial processing, which are critical to ecosystem function.  We investigated the influence of heightened chloride and dissolved organic carbon (DOC) levels similar to those observed in urban streams to identify responses of microbial respiration rates in sub-debris dam sediments.  A dark-bottle biological oxygen demand study was conducted utilizing sub-debris dam sediments collected from forested, urban and restored-urban streams from within the Baltimore metropolitan region.  Sediments were treated with elevated chloride (1500 mg/l), a DOC inoculum, in a full factorial design.  Within sites, the effect of chloride was variable, but generally reduced rates of microbial respiration.  This interacted with DOC addition, but DOC caused a predictable increase in respiration rates.  Results suggest that increasing loads of road salt deicer to streams could alter the capacity for carbon to be metabolized within sediments, with the effective amount of change depending on the ecological condition of the stream receiving such surface runoff.