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BRATTLEBORO — One lesson learned since Tropical Storm Irene swept through the area is that the term "100-year storm" should be retired.

"We are getting those levels of storms on average every 10 years," said Marie Caduto, watershed coordinator for the Southern Vermont office of the Department of Environmental Conservation.

Though the July storms that caused localized damage this year weren't as intense as Tropical Storm Irene 10 years ago, they still brought to mind the devastation the region woke up to on Aug. 28, 2011.

"With climate change, these storms will get worse and happen more often," Caduto said.

Some of the improvements were done around Guilford, Vt., to help mitigate future flooding.

"Irene was a wake-up call," said Kathy Urffer, a river steward with the Connecticut River Conservancy. "With climate change, it's really hard to predict what's going to happen when."

But what's not hard to predict, said John Bennett, associate director at the Windham Regional Commission, is the old way of doing things isn't sustainable.

"We've had these problems before Irene," he said.

What's needed, Bennett said, is "a holistic view of the rivers."

One example he cited is the use of riprap to armor river beds and river banks. Following Irene, there was "an over-enthusiastic application" of riprap in many stream channels in Southern Vermont.

"Folks put in lots of big rocks trying to stabilize stream bottoms," he said. "In many cases, they put in more than the stream could actually accommodate."

The result has been to force the problems farther downstream, Caduto said.

"It increases erosion where the rock starts and where it ends," she said. 

And, with increased temperatures due to climate change, the installation of riprap also has an unintended consequence that can be harmful to aquatic life, Caduto said.

"When a summer rainstorm hits hot rock it heats up the water," she said. "That certainly has a habitat impact for fish."

Another practice that needs to end is river berming, Bennett said.

"Berms prohibit the streams from accessing the flood plains," he said, again pushing the problem downstream.

CRISIS MODE

Those interviewed by the Reformer were quick to point out that though the fixes in the immediate aftermath of Irene weren't optimal, towns were doing their best to get back to some semblance of normal, and that included quick fixes to repair and reopen roads.

"People were doing the best they could in a particular moment in time without the information they needed," Urffer  said.

"Every town had multiple issues and the state wasn't able to keep up," said Ron Rhodes, the director of restoration programs for the Connecticut River Conservancy. 

"Along Route 9 we didn't have a lot of choice but to use riprap to get the road back open," Caduto said.

That meant going back in over the past 10 years and removing riprap and rebuilding along the river banks to prevent erosion. As an example, Rhodes pointed to work done in Adams Brook in East Dover.

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"They fixed the road but in the process, destroyed the brook," he said.

Riprap was installed along the banks and on the riverbed, all of which had to be removed.

In July, the work Connecticut River Conservancy and other organizations have done to stabilize river banks, including removing riprap and berms and planting native vegetation, survived the torrential downpours, Rhodes said.

"We think of this as a race to get as many projects going as soon as possible so that we have more resilience in the face of the changes," Urffer said.

"A good example is culverts," Rhodes said. If a 2-foot culvert blows out, he said, it doesn't make sense to replace it with another 2-foot culvert. "We've learned bigger is better. Putting in a big pipe is good. A box culvert is better. And a bridge is always better than a culvert. There's more room for water to flow and less likelihood it will get clogged up."

"The flow we got during Irene proved very clearly we needed to make those replacements larger," Caduto said. "Not just for increased flows, but also so sediment and debris can pass through without jamming up and causing problems."

Ditches alongside roads have to be made bigger and kept clean to prevent sediment and detritus from making its way into the region's waterways, she said.

Rhodes understands how bigger also means more expensive, and many towns need help paying in the short term to avoid paying even more in the long term.

"In the short term, we don't want to raise taxes," Rhodes said. "But if we compare that to the long-term costs, it's cheaper to fix some of the problems before we have the next Irene because it's going to cost two to three times as much."

The Legislature made changes to how Clean Water Act money was disbursed to help pay for repairs and replacements and the state appealed a FEMA denial for reimbursement for a culvert replacement in Townshend. FEMA eventually found in the state's favor, determining the culvert could be paid for by the Public Assistance program created by the Robert T. Stafford Act as hazard mitigation. The decision allowed the state to acquire funding to repay other municipalities for work done following Irene.

WATER SUPPLY

One of the paradoxes of climate change is that increased flooding events are often separated by drought conditions, when very little rain falls. This can lead to an uncertainty over water supply, Urffer said.

"Surface water has been one of the things that we haven't thought about a lot," she said. "But with climate change, we may not have all the water we need."

How do you capture the water so it's stored, Urffer asked, rather than rushing downstream, causing damage and eventually ending up in the Long Island Sound?

One solution might be farm cisterns, where rain is captured and stored for drought conditions. Rain barrels should also be encouraged, she said.

But how such systems might affect the environment is not totally known, she said.

In 2020, the Legislature established the Surface Water Diversion and Transfer Study Group to figure out how best to address these challenges.

Building more check dams to slow down water flow and increase infiltration can also help to recharge surface and groundwater, Urffer said.

Check dams, obstructions placed in human-made channels and ditches, also allow sediments to settle out and not be carried downstream, she said.

"We talk about death by a thousand cuts, but each of these small projects is healing by a thousand Band-Aids," Urffer said.

Rhodes said there is no shortage of these small projects in the Connecticut River watershed.

"There are thousands of dams and hundreds of thousands of culverts that need to be replaced," he said. "And all of the farms have erosion to be stopped and berms to be removed."

To get these projects done requires coordination between non-governmental organizations such as the Connecticut River Conservancy and the Natural Resources Defense Council and government agencies such as regional planning commissions, conservation districts, the USDA, U.S. Fish and Wildlife, state departments of environmental conservation, and the Vermont Housing and Conservation Board.

Together, they find funding from various sources, packaging them together to tackle projects one by one, Bennett said.

"We team up to work together to try to address these problems," he said. "We are different partners with different areas of expertise. No single entity has the bandwidth to do it all."

Bob Audette can be contacted at raudette@reformer.com.