The Hinkle Creek Paired Watershed Study was initiated to carry out two overarching goals: to investigate the environmental impact of contemporary forest practices on non-fish-bearing streams and downstream in tributary and main stem fish-bearing streams. This presentation serves as a summary of some of the results for the studies in Hinkle Creek.  Statistically significant increases in water yield, summer low flows, peak flows, and storm flows were detected as a consequence of timber harvest and the subsequent silvicultural activities. Statistically significant increases in sediment yield were also detected. The increases in sediment yield were not consistent with the literature; however they were highly correlated with the observed increases in water yield. Statistically significant increases and decreases were detected in maximum and minimum daily stream temperatures in the non-fish-bearing tributaries, fish-bearing tributaries, and the main stem as a consequence of the two harvest entries. Statistically significant increases in nitrogen were detected as a consequence of the timber harvest and the subsequent silvicultural activities. Nitrogen was the only nutrient that responded to the silvicultural activities. In Hinkle Creek the pacific giant salamander was the only amphibian that was abundant enough to study. In the two years after the first harvest entry, the data did not support the hypothesis that there was any change in the abundance of salamanders.

Here we evaluate the response of a headwater fish community to forest management using a before, after, control, impact (BACI) study design. Annual fish abundance and biomass estimates are from a census of pool and cascade habitat units over the fish-bearing portion of both the reference and treatment catchments. Movement, survival, and growth were estimated from the monitoring and recapture of salmonids marked with passive integrated transponder (PIT) tags. Sampling consisted of an annual electrofishing and marking event during the low-flow period (2001-2011), and beginning in the winter of 2003, there were three annual mobile antenna PIT-tag survey events in December, March, and June. Additionally, continuously operating swim-through antennas were located at the downstream end of each stream segment. The study calibration phase occurred 2001-05. Treatment-1 (2006-2008) consisted of stream adjacent logging without retention of standing tree buffers with harvest units occurring in channels upstream from channel sections inhabited by fish. During Treatment-2 (2009-2011), there was stream adjacent logging with standard buffers as prescribed by current forest practice regulations. Analysis occurred at two spatial scales, tributaries only and catchments. Overall, very few detectable changes in habitat or biologic parameters were observed in conjunction with either treatment.

Fertilizer was applied in 2004 and the response of the nutrient levels in the water was measured. Stream water samples were analyzed for nitrogen, phosphorus, calcium, sodium, potassium, magnesium, sulfate, chloride, and silicon as well as specific conductance, pH, and alkalinity. All treatment watersheds showed a statistically significant increase in NO3 + NO2 concentrations after clearcutting (p < 0.001). The slope of the streambed through the disturbance was a stronger predictor of the magnitude of the response than was the magnitude of disturbance. Ammonia and organic nitrogen displayed notable increases after harvest treatment, but these increases were attributed to increases in the control watersheds. Phosphorus showed a response to timber harvest in one headwater stream. The remaining nutrients showed a small decrease in the control and treatment watersheds for the period after harvest. The storm response results showed that NO3 + NO2 concentrations in stream water increase with discharge during small storms that occur after periods of negligible precipitation.

Coastal cutthroat trout Oncorhynchus clarkii clarkii are the most widely distributed native salmonid in the forested watersheds of western Oregon. The initial Alsea Watershed Study demonstrated negative impacts on the abundance of cutthroat trout due to logging practices of the day. Here we report on abundance, size, growth, and condition of coastal cutthroat trout before and after logging under the current forest management practice regulations using a before, after, control, impact (BACI) study design with Flynn Creek and Needle Branch as the control and impact streams respectively. Relative abundance estimates are from a census of pool habitats using single-pass electrofishing and relative growth is from the recapture of individuals implanted with passive integrated transponder tags. A significant increase in age 1+ cutthroat trout biomass and abundance was observed post-harvest in Needle Branch relative to Flynn Creek (p=0.04 and 0.01 respectively). There was also a significant shift in the spatial distribution of cutthroat biomass in Needle Branch (p=0.04) in an upstream direction post-treatment suggesting that increases in cutthroat trout were spatially linked to the location of the harvest unit. There was no evidence for a treatment effect on mean fork length or the 90th percentile of fork length for age 1+ cutthroat trout (p=0.32 and 0.24 respectively). This result was supported by an absence of evidence for a treatment effect on relative growth rate.