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Oregon Cities Aim at Mitigating Harmful Urban Effects


Wild salmon depend on rivers and streams for spawning. Researchers say various detrimental effects from urban areas have contributed to the decline of salmon populations, and mitigation efforts in Oregon and other Pacific Northwest cities would go a long way toward salmon recovery and restoration. Photo courtesy of Oregon Fish and Wildlife Department.

When the Pacific Northwest salmon fishery collapsed in 2006, commercial and recreational fishermen, perhaps for the first time ever, agreed on a fisheries issue: the need to mitigate the factors causing the decline and collapse.

While the past three salmon seasons brought somewhat of a reprieve for commercial salmon fishermen, the crash and snail's-pace recovery are part of what fishery managers say is a boom-and-bust cycle for salmon that will continue until they find a solution to overcome certain factors that prevent the fishery from restoration to a steady commercially viable status. Some fishery advocates fear that if nothing is resolved, the salmon fishery in both Oregon and California could permanently collapse. If so, it would end not just a commercial enterprise, but a cherished way of life.

Experts say salmon could very well survive dams, hatcheries and continually varying ocean conditions contributing to salmon decline if not for other factors, among them the ever-increasing amounts of water extracted from freshwater rivers and streams where the fish must migrate to spawn. Farm irrigation is a prime extractor of river and stream water, and until recently, restoration of salmon habitat in the Pacific Northwest focused mainly on runoff and other negative contributions from rural areas primarily dominated by agricultural and forested lands.

But more and more, researchers are considering and investigating the impact of urban areas on the well-being of these commercially and culturally vital fish. They say metropolitan areas and even small towns can have a major impact on the waterways carrying fish, but leaders in many Pacific Coast cities – with Oregon leading the way – are taking steps to mitigate those effects. The issues, policies and impacts of urban areas on salmon, steelhead and trout are the focus of a new book, "Wild Salmonids in the Urbanizing Pacific Northwest," published by Springer.

While contaminants and toxic chemicals are two of the most obvious impacts, urban areas can also heat up rivers, alter stream flows, and have other detrimental impacts, says Carl Schreck, a professor of fisheries and wildlife at Oregon State University (OSU) and a contributing author.

"One of the biggest issues with cities and towns is that they have huge areas of compacted surfaces," he notes. "Instead of gradually being absorbed into the water table where the ground can act as a sponge and a filter, precipitation is funneled directly into drains and then quickly finds its way into river systems."

Schreck says urban areas "can do something about it," and several Oregon cities near the coast - among them Salem, Eugene, Corvallis and Portland - are leading the way. For example, Schreck says Portland has put in permeable substrate in many areas, used pavers instead of pavement, and "boasts a number of rain gardens, roof eco-gardens and bio-swales. When it comes to looking for positive ways to improve water conditions, Portland is one of the greenest cities in the world."

The book's roots trace to 1997, when the Oregon legislature established the Independent Multidisciplinary Science Team (IMST) to focus on natural resource issues. Co-chaired by Schreck, the team created a report in 2010 for Governor John Kitzhaber and the legislature, providing an in-depth look at the issues and policies affecting salmon success in Oregon and the influence of urban areas. The report's acceptance by folks in many Oregon communities stirred researchers to write the book, which features dozens of contributing scientists.

"One of the things we're trying to do is add the social dimension to the science," says Kathleen Maas-Hebner, a senior research scientist with OSU's fisheries and wildlife department and one of the book's editors. "The science is important, but the policies and restoration efforts of communities are a huge part of improving conditions for fish."

Researchers say the location, size, and distribution of urban areas along streams, rivers, estuaries and coasts "have directly and indirectly altered and degraded wild salmon populations and their habitats."

"Although urban and exurban areas typically cover a smaller fraction of the landscape than other land uses combined, they have profound and often grave consequences for local ecosystems, aquatic and terrestrial populations, and water quality and quantity," they note. Their central question is: Can viable wild salmon populations coexist with humans in urban and urbanizing areas? While their focus is on wild salmon in the Pacific Northwest, the book's ideas and suggestions extend to salmon-supporting watersheds threatened by concentrated human settlement anywhere.

"Despite countless management initiatives to recover these vital species and their habitats, wild salmon have continued to decline inexorably over the past century and a half in the Pacific Northwest," the book notes. "While it has long been understood that intensive land use severely degrades salmon bearing streams, urban areas have received much less focus in salmon management and rehabilitation efforts. Far more attention has been placed on salmon impacts from factors such as timber harvest, agriculture, dams, mine operations and river channel modification. Yet many salmon must traverse substantial urban areas at least twice in their lifetimes - once as out-migrant juveniles and again as adults returning to spawn. Moreover, many urban areas exist along important river confluences and slough areas that were historically critical refuges for salmon at various times in their lifecycles. Finally, human populations and economies continue to both increase overall and further concentrate in urbanizing areas. Cities and rural-residential development constitute an ever increasing part of the impact on wild salmon."

Researchers say boosting understanding of the growing threat to wild salmon populations from urban areas is "imperative" and fishery advocates face a "desperate need" to enhance the survival and recovery of those populations in the face of urban growth and development.

Many Northwest residents, scientists note, remain unaware of the "everyday ways in which human activities can affect water quality and conditions, and thus fish survivability."

Products from lawn fertilizers to shampoos eventually make their way into rivers and can trigger algal blooms. Septic tanks can leach into the groundwater and other by-products of daily living also find their way into rivers, streams and oceans.

"Fish can get caffeine, perfume and sunblock from our groundwater," Schreck said. "The water that flows from our cities has traces of birth control pills, radiation from medical practice, medical waste, deodorants and disinfectants. We could go on all day. Suffice it to say these things are not usually good for fish."

The most effective strategy to counteract the ill effects of such infiltration might lie in reducing the use of contaminants through public education and awareness, and by banning the worst ingredients, Maas-Hebner says. "Phosphates, for example, are no longer used in laundry detergents," she notes. "Fertilizer and pesticide users can reduce the amounts that get into rivers simply by following application instructions. Many homeowners over-apply them."

Another hazard of urban areas is blocking fish passage through small, natural waterways. Many streams that once meandered are channeled into pipe-like waterways, and some culverts funnel water in ways that prevent fish from passing through, Schreck says. "If the water velocity becomes too high, some fish simply can't or won't go through the culvert," said Schreck, who in 2007 received the Presidential Meritorious Rank Award from the White House for his fish research. "Some cities, including Salem, Oregon, are beginning to use new and improved culverts to aid fish passage."

Smaller communities like Florence, Oregon offer incentives to developers for maintaining natural vegetation along waterways.

Despite mitigation efforts in many Northwest cities and towns, researchers say urban hazards for fish are on the rise. One of the most perplexing problems lies in the fact that no one knows what effects the increasing number of chemicals humans create and use might have on salmon.

"There are literally thousands of new chemical compounds being produced every year and while we may know the singular effects of a few of them, many are unknown," Schreck said. "The mixture of these different compounds can result in a 'chemical cocktail' of contaminants that may have impacts beyond those that singular compounds may offer. We just don't know. The research is well behind the production of these new chemicals, and that is a concern."

Research on urban contributions to fish habitat degradation indicates that good culverts can enhance and enable fish passage.

Getting the word out is the undercurrent of the book, which "integrates science with policy and social aspects of urbanization to provide a comprehensive review of how human activities in urban and rural residential areas alter aquatic ecosystems and affect wild salmon populations and their habitats in North America's Pacific Northwest." It outlines successes and challenges of salmon rehabilitation and restoration in Oregon, and suggests how lessons learned from those efforts might apply elsewhere for both salmon and non-salmon waters. It also discusses potential strategies to minimize future urban impacts and restore aquatic ecosystems and habitats to support healthy salmon populations in urban areas.

The book is available from Springer online at


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