It's been three years since floodwaters forced the Suncook River through an Epsom gravel pit, birthing a new waterway and sucking nearly two miles of the former channel dry. As the river's sagging banks continue to swallow trees and rocks and deposit gritty sediment downstream, the topical damage is clear. What's going on beneath the surface, however, is a murkier matter.

Little is known about the full impact the 2006 Mothers Day flood had on aquatic life and wildlife species around the river. Studies exploring river stabilization alternatives examined the ecological consequences immediately following the avulsion, and though various agencies and third parties have done their own research, no comprehensive analysis of the overall impact exists.

A 2007 report from Vanasse Hangen Brustlin, Inc., an engineering firm hired by the state to draft various restoration alternatives, labeled the ecological consequences of the avulsion as "extreme," affecting in-stream habitats, upland areas, wetlands and neighboring surface waters.

When that study was conducted two years ago, about 150,000 cubic yards of sediment had been introduced from the new river channel, impairing water quality for aquatic life and creatures living around the banks. As the river naturally attempts to restore balance, erosion along the banks upstream continues to drop silt, clay and dirt, which are carried downstream. That fogs the water and makes surrounding land more prone to floods, said Eric Orff, a retired state wildlife biologist who lives along the Suncook in Epsom, about three miles downstream from the avulsion site. It's especially bad after rainstorms, he said.

"Any time we have a rain event, the river gets much browner than it used to," Orff said last week. "The river doesn't have the variety of habitat it did before. Parts are much shallower, the deep holes have disappeared, and there's less cover for fish."

Before 2006, Orff, who's lived in his Epsom house for more than 30 years, could count on one hand the number of times the Suncook had flooded. Now he estimates certain areas downstream overflow the banks at least two or three

times a year, turning farmland into marshy bogs, not to mention causing nightmares for residents who've sustained significant damage to their homes and properties.

Higher waters have affected ducks, geese and small songbirds that build nests along the river, Orff said. When flooding occurs, their habitats are washed away, and though they can re-nest in more stable areas farther down the river, Orff said it can mean fewer eggs that season. Based on his observations, there's less nesting downstream now than before the avulsion.

"It's not like it's wiping out an entire species (of bird)," Orff said, "but they've been impacted."

For Elena Traister, a UNH doctoral student who conducted a yearlong study on how the avulsion affected the river's vitality, her most noteworthy discovery was what the shifting waters did to the macro invertebrate population - black flies, midges, mayflies, stoneflies and larvae, for example - in parts of the river over time.

Traister estimated she typically found up to 200 types of macro invertebrates in samples taken upstream immediately after the avulsion.

But downstream, "I would find between zero and five. They were enormous differences," she said. "Initially the thought was, okay, this is a new river. Maybe they haven't gotten here yet. Maybe more and more will show up over the course of the study. That wasn't the case.

"The big picture was that a year after the avulsion, there appeared to be long-lasting effects on water quality and macro invertebrates," Traister said. "That certainly may have changed in the last few years."

Endangered mussels

One species that garnered environmentalists' attention following the avulsion was the brook floater, a species of mussel on the state's endangered species list. Days after the flood, about 1,200 brook floater mussels were rescued from the emptied channel near Huckins Mill Dam, tagged and eventually relocated upstream in Chichester.

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