Stream temperature change detection for state and private forests in the Oregon Coast Range

Abstract

[1] Oregon's forested coastal watersheds support important cold-water fisheries of salmon and steelhead (Oncorhynchus spp.) as well as forestry-dependent local economies. Riparian timber harvest restrictions in Oregon and elsewhere are designed to protect stream habitat characteristics while enabling upland timber harvest. We present an assessment of riparian leave tree rule effectiveness at protecting streams from temperature increases in the Oregon Coast Range. We evaluated temperature responses to timber harvest at 33 privately owned and state forest sites with Oregon's water quality temperature antidegradation standard, the Protecting Cold Water (PCW) criterion. At each site we evaluated stream temperature patterns before and after harvest upstream, within, and downstream of harvest units. We developed a method for detecting stream temperature change between years that adhered as closely as possible to Oregon's water quality rule language. The procedure provided an exceedance history across sites that allowed us to quantify background and treatment (timber harvest) PCW exceedance rates. For streams adjacent to harvested areas on privately owned lands, preharvest to postharvest year comparisons exhibited a 40% probability of exceedance. Sites managed according to the more stringent state forest riparian standards did not exhibit exceedance rates that differed from preharvest, control, or downstream rates (5%). These results will inform policy discussion regarding the sufficiency of Oregon's forest practices regulation at protecting stream temperature. The analysis process itself may assist other states and countries in developing and evaluating their forest management and water quality antidegradation regulations.

Response of western Oregon (USA) stream temperatures to contemporary forest management

“…We expand our assessment of stream temperature beyond the water quality standard-focused weekly maximum temperatures reported by Groom et al (2011) and examine daily maximum, minimum, and mean temperatures as well as diurnal fluctuation, in order to better capture the spectrum of temperature changes following harvest. The implications of findings for this study likely extend to other regions with similar physical and biological characteristics, stream temperature concerns, cold-water fisheries, and prescriptive riparian zone protections such as Idaho, Alaska, British Columbia, Washington, and California.…”

“…Study and analysis designs must therefore be able to separate this inherent variability from potential harvest effects. Groom et al (2011) evaluated changes in stream temperature following harvest in the Oregon Coast Range. Their study design was developed to account for aforementioned spatial and temporal variability.…”

Estimation of forest harvesting-induced stream temperature changes and bioenergetic consequences for cutthroat trout in a coastal stream in British Columbia, Canada

“…Statistical approaches such as generalized least squares regression can account explicitly for the presence of autocorrelation in regression residuals, and have made it possible to develop reliable pre-harvest regression models for daily stream temperature using 1-2 years of data (Gomi et al 2006;Groom et al 2011). In this study, we analyzed daily stream temperature data from a paired-catchment study in order to understand seasonal effects of forest harvesting on stream temperature and its biological consequences.…”

A Review of Performance Bonding in Forest Policy Settings

“…PCWS in Oregon is an example of an ambient-based water quality standard [79]. The criteria in PCWS set a limit of 0.3°C for the allowed post-harvesting increase in stream temperatures in fish bearing water bodies when compared to natural reference temperatures that are typical to the area in question.…”