The
Increasing Importance of River Restoration in Response to Climate Change
By Tim Purinton and Russ Cohen,
[The following article is adapted from “River Restoration and Dam Removal: Adapting to Climate Change”, which appeared in the September/October 2007 newsletter of the Mass. Association of Conservation Commissions.]
Conservation Commissions, along with land trusts, watershed associations and other resource protection advocates, have always been on the front line when it comes to protecting rivers and streams from the steady encroachment of development and land use change. The ongoing struggle of keeping up with landscape alterations is made even more difficult today by the sobering global warming forecasts for the region.
According to the Cambridge, MA-based Union of Concerned Scientists(UCS)’s report Confronting Climate Change in the U.S. Northeast, Massachusetts’ air temperatures are on the rise and may increase up to fourteen degrees Fahrenheit in the summer months by century’s end. Rainfall is also forecasted to increase, as is the frequency and severity of heavy rainfall-induced flooding and hot and dry weather-induced drought events. In other words, there’s a prediction of wetter wet periods and drier dry periods in the future that contrasts with historic weather patterns for the region of more-or-less even amounts of precipitation (about 3.5 inches) each month. Thus, the higher high flows and lower low flows in our rivers and streams caused by development and the proliferation of impervious surfaces, which already place our riverine organisms and ecosystems under significant stress, is predicted to be further exacerbated by the adverse impact of global warming-induced climate change. [Check out Water, Energy, and Climate Change, a recent EPA Watershed Academy Iwebcast for a further discussion of these impacts, and suggested responses to mitigate the adverse impacts of climate change on rivers.]
Scientists from the UCS and the Intergovernmental Panel on Climate Changepredict that plant and animal species will seek to adapt to these changes by attempting to migrate to cooler areas. Rivers and vegetated riverbanks are critical corridors for migration and seasonal movement for fish and wildlife, and thus play an important role in their future survival. [Human communities will have to adapt too – see, e.g., Adaptation to Climate Change in the Northeast United States: Opportunities, Processes, Constraints.]
Although all of our rivers and streams are important, cold water and coastal streams provide unique aquatic habitat and support species under direct threat from global warming-induced climate change. [See, e.g., an EPA-produced brochure entitled Climate Change and Cold Water Fish: Is Trout Fishing An Endangered Sport?; Effects of Global Warming on Trout and Salmon in U.S. Streams, a report issued in 2002 by Defenders of Wildlife; and testimony presented to the U.S. Senate earlier this year by Senior Scientist Jack Williams of Trout Unlimited.] For example, Eastern Brook Trout need specific “coldwater” (68°F or lower) conditions to thrive, especially in the summer. And the once ubiquitous alewife could face even more dramatic declines as ocean temperatures rise and decreased summer stream flows impair juvenile habitat.
Massachusetts Rivers are highly fragmented and have the dubious achievement (largely due to the state’s prominent role in the Industrial Revolution of the 19 th and early 20 th centuries) of one of the highest concentrations of dams per linear mile of stream in the nation. Dams not only block or impair upstream fish passage, but also raise water temperatures, inundate spawning habitat and create impediments to the migration of juvenile fish. In other words, dams present a significant impediment to the ability of our aquatic and other riverine organisms to cope with the effects of global warming-induced climate change. Add to this the more unpredictable precipitation and “flashier” streamflow patterns triggered by climate change, and the steady beat of lost open space, and the importance of river restoration becomes even more acute.
The removal of dams and other barriers to fish and wildlife movement in and along rivers and streams presents a real opportunity to enhance the ability of our riverine organisms and habitat to withstand the effects of climate change , as well as safeguard important infrastructure from severe flooding. While it has always been a good idea to preserve the connectivity of river and stream corridors and prevent habitat fragmentation by dams, dropped culverts and other barriers (see Riverways’ River Continuity web page to learn more about what we and others are doing to address this issue), it is now more important than ever that we keep these vital riverine “escape routes” open to enable trout and other sensitive species to find safe refuge in tenable habitats as they cope with the stream heating and other adverse impacts brought on by global warming.
Trout Unlimited (TU) and The Nature Conservancy (TNC) have each outlined conservation strategies to combat the impacts of global climate change and each has stressed the importance of reducing fragmentation. According to TU’s Conservation Vision, “In addition to protecting habitat…we must reconnect high quality habitats to upstream and downstream areas by increasing river flows and removing barriers to migration.” (Trout, The Journal of Coldwater Fisheries Conservation, Summer 2007). Groups like TU, TNC and Riverways take a multi-pronged approach to restoring connectivity, through restoration projects to remove or retrofit barriers, working to increase funding available for restoration (click here for one potential funding source), and working on policy initiatives to ensure that infrastructure is designed and maintained with the environment in mind.
Conservation Commissions can play a direct and beneficial role in mitigating the adverse impacts of global warming-induced climate change on riverine organisms and habitat by enabling the removal of unnecessary dams and other man-made barriers on and along rivers and streams . Such restoration projects can be initiated by land trusts and other landholding organizations, businesses and other private landowners as well as the municipalities themselves. To assist in the process of river restoration, the Mass. Department of Environmental Protection (DEP) will soon be issuing a guidance document that should facilitate commissions’ review and approval of dam removal projects (info on the document will likely be posted on DEP’s Wetlands web page once it’s issued). The guidance will make it clear that the restoration of natural riverine functions and values is a beneficial action, and that commissions will continue to have jurisdiction over the restored river corridor via the Riverfront Area and other applicable wetland resource areas. In the meantime, Conservation Commissions in the Towns of Plymouth, Wareham, Becket, Dalton, and Barre have understood the importance of dam removal and have already permitted pro-active dam and barrier removal projects to restore the integrity of their rivers and streams (click here for more info on these and similar projects). With new guidance from DEP, the hope is that many other cities and towns will follow, as will land trusts and other private landowners. Please contact Tim Purinton at Tim.Purinton@state.ma.us or (617) 626-1542 for advice and/or assistance on a potential dam or other man-made barrier removal project.
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