Study lists causes, solutions for Mohawk Valley flooding

The U.S. Army Corps of Engineers presented the results of a yearlong study of flooding in the Mohawk
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The U.S. Army Corps of Engineers presented the results of a yearlong study of flooding in the Mohawk Valley on Wednesday, listing probable causes and possible solutions to the costly, recurring disasters.

Corps representatives outlined the yearlong study at the Arkell Museum and told a small group present that there are ways to help lessen flooding’s impact and reverse some of its damage.

One major hitch: Someone other than the federal government has to come up with millions of dollars to further study the problems in greater detail before even attempting to address them.

Project Manager Jenifer E. Thalhauser and watershed planner Jason A. Shea said that in order for their work to continue into the next phase, a non-federal partner who can bear half of the cost has to be identified.

Shea said it would cost between $3 million and $5 million to perform in-depth studies that would identify specific projects aimed at minimizing the damage, both economically and ecologically, that flooding causes in the basin.

A partner would have to sign on to either contribute half of that work’s cost or pay for part of it with cash and the remainder with in-kind services like labor and equipment.

Whether any state agency ultimately agrees to play that role remains to be seen.

In New York, the corps typically looks to the state Department of Environmental Conservation as a local partner.

But DEC Region 4 Director Gene Kelly on Wednesday gave a pessimistic view of that possibility as it relates to flooding along the Mohawk.

Kelly said he believes the DEC is a “critical player” in the initiative, but added: “One thing I can assure you, it doesn’t mean there’s going to be any money on the table.”

Problems identified

During the Mohawk River Watershed Reconnaissance Study, considered an initial step in the U.S. Army Corps of Engineers’ process, a team of biologists, engineers and an archaeologist identified obvious signs of damage from the overflow of creeks, streams and tributaries leading to the Mohawk River.

Damage includes erosion, negative impacts to navigation and road washouts.

* Channel and bank erosion has caused the loss of natural stream meandering, narrowing of stream and river channels and the creation of sediment islands and river “braiding” — a situation that leads rivers in several directions between new islands of deposits formed by sedimentation. Also problematic are the creation of navigational hazards, erosion and damage to canal structures.

* Constrictions in the river and its tributaries, including rock ledges and abandoned bridges, are backing up the flow of water but could be removed to restore a higher level of flow.

* Large dead trees, live vegetation and boulders are also trapping sediment, which itself is now growing vegetation and creating new islands, further restricting the flow of water, according to the draft report.

* Constriction in the river’s channel is considered a major cause of ice jamming, as is the tight bend in the river at Rexford Knolls, according to the draft report.

The U.S. Army Corps of Engineers’ team could simply decide “no action” is an appropriate next step, but Thalhauser said there’s a variety of issues that could be addressed. “There are real problems [in the watershed],” she said.

Potential remedies

If a cost-sharing partner is found, several projects, both long- and short-term, could help alleviate some of the flooding, according to the draft report.

* Obstructions including abandoned piers at trolley and railroad bridges in the river’s path, such as the ones between Niskayuna and Alplaus, can be removed from the river.

* Electronic devices called “pressure transducers” could be installed in the river, providing real-time warnings that the river’s flow is being constricted.

* Dredging between locks 6 and 7 hasn’t been done in decades, according to the report, and ice jamming has increased since the dredging was stopped.

* A large crane with an I-beam attached to it can help break up ice at the river’s bend in Rexford.

* A regular debris removal program could be organized and put into motion, allowing the water to flow naturally.

* Levees or flood walls along portions of the canal could help prevent floodwater from inundating structures and roads, but that option is costly, according to the report.

* Ice control structures can also be installed. These help retain chunks of ice while insulating the water and reducing icing and, during a melting period, help minimize ice-jam flooding downstream.

Wetland loss

Wetlands are considered key parts of a region’s ability to accommodate flood water, and the team found evidence of the gradual loss of wetlands in the Capital Region.

Of the 600 acres that make up the Vischer Ferry Nature Preserve in Clifton Park, the corps identified 100 acres of wetlands that are degrading because of weed growth, excess sedimentation, nutrient loading and invasive species.

The team is recommending further studies into restoration that could entail excavating excess sediment and replanting native species that help absorb nutrients.

Doing so might benefit waterfowl and other bird species that frequent the preserve, which is designated a Bird Conservation Area, according to the corps.

The restoration of stream banks could help prevent further erosion and help restore habitat, and measures in the Mohawk River itself could also improve and refine the water’s depth, flow velocity and temperature.

“This also generally provides for better habitat and fish passage with more consistent depth and temperature,” the report states.

Thalhauser said the initiative is now in a holding pattern, and the U.S. Army Corps of Engineers is tentatively slated to present its final findings in the fall of 2009.

If no cost-sharing partner is identified by then, the report will be shelved, Thalhauser said.

But it could be revived in the future if a cost-sharing partner makes such a request, she said.

Historical perspective

During a discussion Wednesday, Union College Professor John Garver, one of several authors of a study titled “Major Floods on the Mohawk River: 1832-2000,” said he was not confident that there would be sufficient support for continuing the project.

“I don’t see a partner who can step up,” Garver said.

The Union College Geology Department’s study identified 11 separate major flooding incidents along the Mohawk River between 1832 and 1996, all of which involved ice jams.

Further studies, Garver said, show that there’s been an increase of about 30 percent in the amount of water flowing through the Mohawk River, a factor he suggested be taken into account when riverside development is considered.

Another study reviewed by the team from the U.S. Army Corps of Engineers is the report drafted in 2007 by Schenectady resident James E. Duggan, who points to the massive hydropower dam at Lock 7 in Niskayuna, a concrete structure with no movable parts, as the biggest constriction of flow in the Mohawk River.

Shea said any review, were it to proceed, would include another look at that dam. The corps identified that dam as an issue during a study more than three decades ago.

Several officials offered support for continued studies Wednesday, including U.S. Rep.-elect Paul Tonko, D-Amsterdam.

Tonko acknowledged the difficulties involved in finding an agency in New York state willing to put money behind the idea, but he said changes at the federal level with the outset of a new administration may present opportunities.

Tonko said talk about economic rescue packages is expected to include discussion on infrastructure recovery programs.

The fact that many communities in upstate New York surrounding the Mohawk River are considered economically distressed could provide leverage and incentive for the federal government to provide more funding to the effort, Tonko said.

“There’s got to be a way we can come up with a really lucrative package,” Tonko said.

Categories: Schenectady County

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