Measuring Stream Productivity for the Purpose of a TMDL Assessment

Understanding stream metabolism requires measuring two important metabolic processes i.e. primary production and community respiration. Primary production increases the aquatic dissolved oxygen while community respiration decreases dissolved oxygen. They are commonly used to quantitatively classify ecosystem communities. Excess nutrients input (Le. eutrophication) leads to excess primary algae production, and phosphorous, nitrogen and organic carbon in dissolved forms can alter stream metabolism by increasing algal biomass. The study focused on four streams in North Utah surrounding Cutler Reservoir that range in physical characteristics and water quality. The water in three of the streams is relatively turbid; therefore, due to the poor light penetration, the benthic algae affect on the total production was expected to be minimal. The dark -light bottle method was used to measure primary production and respiration in the streams, and relate those measures to stream water quality and watershed characteristics