Protecting Water Quality- Mica Creek

Forests play a crucial role in collecting and filtering the water that countless organisms depend on — including humans. In our planting, harvesting, and road building, we take comprehensive measures to minimize sedimentation and runoff, with the goal of protecting the water quality and aquatic ecosystems. We follow each state’s prescribed “best management practices” as well as our own procedures that have been refined and improved over decades of research and science-based forestry. Following passage of the Clean Water Act in 1972, many states adopted forest management guidelines intended to reduce forestry’s negative effects on waters. At the time, there was little research showing whether these new guidelines worked.

That’s why PotlatchDeltic undertook a landmark study that was the first of its kind among U.S. forest products companies and remains one of the most comprehensive in length, scope and findings.

In 1990, with help from the U.S. Forest Service and the Idaho Department of Lands, we established the Mica Creek Experimental Watershed — an area southeast of Coeur d’Alene, Idaho, comprising the 6,672-acre catchments of Mica Creek, a tributary of the St. Joe River. While the watershed has been the site of numerous research projects over the years, we created this “living laboratory” for one main reason: to conduct a multi-decade study of the effects of modern forest best management practices on stream water quality and aquatic life.

Over the course of the study, we have worked with scientists from the University of Idaho and other academic institutions to collect data on the effects of tree harvesting, road building, and other practices. The results of that research are published in independent, peer-reviewed academic journals such as Forest Science and presented at scientific conferences. In our leadership roles serving on the Idaho Forest Practices Act Committee, we work to incorporate the results of the Mica Creek research into effective and efficient Forest Practices Act rules. The conclusions to date are encouraging. They show that forest management that adheres to contemporary best management practices has little to no adverse effect on streams’ aquatic life.

Key Findings of Mica Creek Research

• Stream flows generally increase modestly following tree harvests.
• Stream temperature in fish-bearing streams within harvest sites increases slightly in the spring and decreases slightly in the summer.
• Measurable suspended sediment increases in the first spring following thinning or harvesting, and quickly returns to pre-harvest levels.
• Forest management that adheres to contemporary best practices has no detrimental effect on fish, amphibians, or aquatic insect communities.

The findings from the first 25 years of research comparing treated versus control stands have been summarized and published in numerous scientific journals. In collaboration with the University of Idaho, we continue to collect data on water flow, sedimentation, fish, and other key environmental conditions in the Mica Creek watershed. The watershed is now being managed as a working forest – the forestlands that we harvest, replant, and manage for sustainable production of timber. The research and monitoring that are being conducted now provide an ongoing evaluation of the effectiveness of contemporary best management practices.