Logging didn't cause water problems

On June 28, the Mail Tribune reported that an environmental group warns that a substantial portion of the drinking water for some 1.5 million Oregonians could be at risk if a proposed bill to create a timber trust on federal forestlands in Western Oregon becomes law.

This conclusion was based upon a computerized study by the Ashland-based Geos Institute. In the Tribune's article, Dominick DellaSala, the chief scientist at the Geos Institute, was quoted as saying that in 1996, Salem spent $100 million on new treatment facilities after logging in upper watersheds combined with storms led to high levels of sediment in the water supply.

In actuality, the impacts to the city of Salem's water supply from the 1996 storm (nearly a 100-year event) were not the result of "logging in the watershed." A series of investigations by different parties, including the U. S. General Accounting Office, resulted in the same conclusion, that the high levels of "turbidity" produced by the 1996 storm were predominantly the result of "natural geologic hazards" of earth flows and other erosion processes affecting deeply weathered, smectitic clay deposits of the ancestral Western Cascades.

The studies also concluded that the turbidity problem was exacerbated by post-flood water storage in Detroit Reservoir. The GAO report found little direct impact from logging and other land-use activities. Indeed, one of their recommendations was to "dissociate public concern about water quality from dissatisfaction over land management issues, such as timber harvesting and road construction." (Emphasis added)

The 1996 storm did result in subsequent changes to the city's water system. With an increased understanding of the risks posed by extraordinary flood events and in recognition of growing water demand, the city since 1996 has spent more than $180 million on creating additional storage of treated water, increasing treatment capacity and securing additional supplies from alternative groundwater sources. The water from the North Santiam River is normally of very high quality with low turbidity, which allows the city to continue to use slow sand filtration as its water treatment process as was the case before the storm. Slow sand filtration allows the city to save $2 million to $3 million per year over more conventional treatment methods.

Research has found that forest management and practices can have both negative and positive impacts on watershed function depending on the time scale and watershed attribute being evaluated. Indeed, management that reduces the risk of catastrophic fire on BLM lands can help reduce one potential source of increased sediment.

Decisions and choices about forest management need to be based upon sound, field-verified and third party-reviewed science, not modeling by advocacy groups dissatisfied over land management issues. As the public considers forest management options, I hope that the involved parties will carefully consider the full range of social, environmental and economic effects, both negative and positive.

Theodore L. Lorensen of Salem is a retired assistant state forester.

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