Road-related turbidity and suspended sediments is a concern for both commonly occurring and higher magnitude storm events with the potential to negatively affect in-stream biota. Here, we present preliminary results that address whether forest road crossings deliver fine sediments into streams. Specifically, we evaluate evidence of sediment routing before/after road interventions (including new roads and road upgrades - surfacing with gravel) and above/below road crossing within forest harvest units. We hypothesize that newly constructed and upgraded roads will increase turbidity and suspended sediments where roads have hydrologic connections to streams. This response will be heightened during high intensity precipitation. We measured suspended sediment and turbidity above and below road crossing and before (June 2010-Apr 2011) and after (July 2011-June-2012) road upgrades using ISCO samplers in five headwater streams from small-sized watersheds (5-36 ha). We complemented this information with available data from hydrology (four flume stations) and precipitation (two climate stations) during the same time periods. We examined statistical differences of in-stream turbidity and concentrations of suspended sediments below and above road crossing and characterized the behavior of sites before and after road upgrades.

The hydraulic response of the Alsea watershed study to the first harvest produced results to in the streamflow of Needle Branch creek. Deer creek was shown to be a suitable control and that Upper and Lower Needle Branch respond similarly. There is still a lot of work to be done and suspended sediment analysis to complete.

The original Alsea Watershed Study found dissolved oxygen (DO) concentrations at or near saturation in the control (Flynn Creek) and patchcut and buffered (Deer Creek) watersheds. DO concentrations in some reaches of the clearcut and unbuffered watershed (Needle Branch) were found to be substantially below saturation following the 1966 harvest. The depressed concentrations were thought to result from a combination of increased biochemical oxygen demand, reduced solubility due to stream heating, increased biological activity, and reduced reaeration. The Alsea Watershed Study Revisited (AWSR) returns to the same watersheds and provides an assessment of physical, chemical, and biological response to contemporary forest practices. During the pre-treatment phase of the AWRS low DO concentrations were observed in Needle Branch in the summer and fall. These low concentrations coincided with low flow periods. At these times flow becomes “discontinuously perennial” and portions of the stream network go subsurface. We now believe that despite having some of the highest reaeration rates ever measured, certain reaches of Needle Branch are prone to depressed DO concentrations. For some reaches, surface flow during critical late season periods is largely composed of recently emerged groundwater or hyporheic water. Both original study and AWSR findings show high spatial variability in DO concentrations.

Nutrients are one of the factors which limit primary production and can be a water pollutant. Fertilizer can be applied to increase the Nitrogen and therefore increase the growth. The Hinkle Creek Paired Watershed Study addresses concerns about the loss of essential plant nutrients in Douglas-fir plantations and assesses the impacts of forest management on stream water chemistry of fish-bearing streams. The objective is to determine the cumulative impacts to fish-bearing streams of non-fish-bearing streams which are not afforded the protection of un-harvested and unfertilized riparian strips and to compare those impacts with the local impacts of different treatments.