Monday, April 9, 2012

Bleak News for Vermont's Rivers

     It took months for Vermont fisheries biologist Rich Kirn to fully assess the impact of Tropical Storm Irene on the state’s rivers. But on March 5, six months after one of the worst natural disasters in Vermont's history, Kirn presented his findings. 
    The Fish and Wildlife report Impacts to Stream Habitat and Wild Trout Populations in Vermont Following Tropical Storm Irene quantifies and confirms what many environmental groups and landowners had already feared: while the flooding itself wasn’t without ecological consequence, the most substantial damage came from the army of excavators and bulldozers that descended on Vermont's rivers in the wake of the flood.
     Some of the heavy machinery was necessary to protect life and property and to rebuild infrastructure. But “a significant amount of instream activity was also conducted without proper consultation and oversight and for reasons beyond necessary flood recovery,” Kirn wrote, causing habitat destruction that might affect wildlife for decades.
    Or, as the Vermont Natural Resources Council’s Kim Greenwood put it: “We really screwed up.”
    “People got in the rivers that didn’t understand the impacts of what they were doing,” Greenwood said. “Now that the immediacy of Irene has worn off a little bit in terms of public safety, we’re having to face the repercussions of what we did.”
     In the four state streams surveyed for the report, trout populations were reduced by 40 to 70 percent. Significant losses, to be sure, but nothing fish can’t recover from. Previous data showed that localized flooding in places like Lilliesville Brook in Stockbridge caused precipitous drops in population — from 6,000 trout per mile of stream to less than five hundred. But within a few years, populations rebounded. 
    That is, they rebounded in the absence of channelization, riprapping, dredging or gravel mining. All four streams that Kirn surveyed were free from such human disturbances, suggesting that in streams where the work occurred, the population loss was likely far greater — and will last much longer, he said.
    Showing a series of photos of streams from Bethel and Rochester, Kirn’s report explains that the excessive and sometimes unnecessary streambed alteration destroyed trout habitat, creating “homogeneous, overwidened stream channels … lacking the diversity of habitats, flows and depths necessary to support robust aquatic populations.”
     “The habitat has to recover before the fish populations can recover,” Kirn said in an interview.
     The Vermont Natural Resources Council and other groups raised an outcry over such practices in the months following Irene, saying that the work not only degraded habitat but also changed the velocity and direction of waterflow in many of Vermont rivers and streams, exacerbating the potential for future flooding and further endangering homes and communities. But up until now, it was difficult to quantify the extent of damage done.
    Kirn’s report does just that. He and other biologists worked with officials from the Agency of Natural Resources to conduct roadside assessment of stream degradation throughout the central and southern Vermont, and their findings are illuminating: approximately 85 miles of rivers were affected in central and southern Vermont alone — and the estimates are said to be conservative.
     “It was like trying to hit a moving target,” said fisheries biologist Kenneth Cox, of trying to assess the damage while excavators were still roaming the streams. “I would view these numbers as minimal estimates.”
    Approximately 406,000 feet, or 77 miles, of stream were found to have suffered major habitat degradation because of post-flood stream channel alteration. Major degradation is defined as streams that are “largely devoid of habitat.”
     An additional 8.6 miles of stream were found to have suffered minor degradation: effects were either localized or were limited to channelization. The White River was the most affected of any river in the region, with 27 miles of degradation recorded. The Ottauquechee also saw significant damage, with about 9 miles.
     The long-term impact on trout populations is still uncertain. In the absence of post-flood channel alterations, wildlife usually rebounds from a flood within two to four years. But in places where aquatic habitat was severely disrupted through large-scale gravel and wood removal and channel widening and straightening, full recovery could take decades.
     The repercussions are broad. Flood-related threats to houses and communities are exacerbated, and Vermont’s $63 million sportfishing industry may be at risk, Kirn notes. The ecological impact also extends beyond just fish to include amphibians, insects and the mammals and birds that feed on fish.
    “All of this habitat has been grossly altered, and its ability to support populations has declined,” Cox said.
     The reason that so much streambank alteration occurred without review or oversight was due in part to the unexpected nature and widespread devastation caused by Tropical Storm Irene. Normally, streambank alteration is strictly regulated by one of Vermont’s four river management engineers. But in the wake of Irene, the engineers were stretched thin, unable to get to the hundreds of sites across the state where streambank alteration was necessary to rebuild infrastructure, so the state enacted a two-month period in which “verbal permitting” — a discussion over the phone not requiring paperwork — was deemed sufficient.
     Not all instream work performed during that time went beyond verbal authorization, and much of it was indeed essential to the recovery effort. But river scientists and fisheries biologists agree that the situation was chaotic and could have been better managed.
     In the future, biologists like Cox would like to be included in the process. Efforts are currently underway to streamline Vermont’s response to emergency management work in rivers and better educate town officials and the public about how rivers function and what they need to function properly.
     (Namely, they want to meander and flood over time, as well as dissipate their force around bends and in wetlands. Eliminating any of these factors may lead to unpredictable, erratic flooding.)
     Finally, a bill that’s currently before the Vermont House of Representatives might include mandatory river science training for all contractors that operate in streambeds, Greenwood said.
      “Towns’ highway departments and state transportation agencies know how to reconstruct roads, but what they lack is the knowledge and experience in how to do that in a manner that will allow the stream to recover as quickly as possible,” Cox said. He emphasized that he doesn’t want to prevent future recovery work — just allow it to happen in a more sustainable manner.
     As to concerns that the re-channeling and degradation of rivers could exacerbate future flooding, Greenwood said that the lack of snowpack and relatively low spring flood risk means that Vermonters may have lucked out for the time being.
     But, she added, “we’re going to be dealing with these changes for years, maybe decades. We may have lucked out this spring, but we’re not out of the woods yet.”

The Battenkill several years prior to Irene.

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