Lake Champlain Tributaries Summary

adapted from Vermont Fish and Wildlife Wildlife Action Plans

These waters include the lower-most portions of tributaries that empty into Lake Champlain. On many rivers and streams this is defined at its upstream end by the first major waterfall or cascade, called the principal fall line. On streams which do not have this abrupt elevation change, the upstream limit for is roughly 150 feet above sea level. The SGCN supported in these waters are numerous, with many found nowhere else in the state but in here and Lake Champlain. There are several factors accounting for the unique aquatic assemblages found here, including: glacial history and ancient routes of colonization from the west and south; the barrier to upstream migration presented by the principal fall line; and the generally warmer temperatures and finer substrates found here compared to those in higher elevation areas of Vermont. Unique species include many fishes and freshwater mussels, the common mudpuppy, and the spiny softshell. Key features include riffles, runs, and long pools with a variety of dominant substrate types. Small gravel, sand, and finer substrates are more dominant in the lowest reaches of these streams and rivers. Woody debris is prevalent, especially in deep holes in pool sections.

Lake Champlain Tributaries Condition

Current Condition: Some of the most heavily human-populated areas of the state occur adjacent to river sections included in this community type. While the larger volumes of water carried by the large rivers in Lake Champlain tributaries do afford a greater diluting potential than found in smaller rivers and streams, these Champlain tributaries are located in an area of the state where the intensity and frequency of insult to the aquatic habitat from human use is expected to be greater. For example, stormwater runoff reaching the lower Winooski River from developed lands is much greater than in most other Vermont fluvial communities. Stormwater runoff from developed lands increases the amount of sediments, nutrients, and contaminants that reach rivers instead of being trapped by the soil and vegetation. Floodplains function, in part, to absorb runoff and deliver it slowly to rivers through the soil. Paving of land sends water more directly to streams and rivers, in essence bypassing the floodplain. This creates a scouring effect on riverine habitat, due to the more extreme fluctuations in velocity of stormwater runoff.

Pollutants enter these rivers from various non-point sources as well. Agricultural lands located adjacent to rivers within these watersheds can contribute excessive amounts of silt, nutrients, and pesticides to the systems when adequate riparian buffers are not maintained. In such instances, excessive sediments can cover coarser river-bottom substrates needed by many SGCN, as well as covering some of these species themselves. Also, salt from roadways makes its way into rivers, degrading the water quality. These and other sources of non-point pollution are likely the greatest contributors of contaminants to these systems. These pollutants comes not only from adjacent lands, but from the entire watershed.

Accidental contaminant spills are rare, but can have immediate and devastating effects on the aquatic environment and the SGCN that live there. Chemicals, manure, industrial waste, and other potential contaminants stored in areas where they could reach these rivers or their tributaries if released are significant problems. Bridges and riverside roads and railways also present long stretches where accidental spills into rivers and streams can occur. A catastrophic contaminant spill could (and has) easily wipe out entire SGCN populations. As with other sources of pollution, this problem comes from the watershed upstream as well as adjacent lands.

Direct loss of habitat occurs when fill material is placed on the river bottom. Examples of this include riprapping to stop toe erosion along streambanks, placement of piers or causeways to accommodate bridges, and construction of boating access facilities. Direct mortality of freshwater mussels, which live on the river bottom, is sometimes the result of these activities within lower Champlain rivers. The replacement of natural substrates with large stone provides reduced or unsuitable habitat for recolonization by bottom-dwelling animals. The construction of buildings and roads adjacent to rivers creates a hazard for the structures, increasing the potential that bank stabilization will be pursued.

Two dams on major rivers within the Lake Champlain tributaries have cut off migration for fishes and mussels, and have resulted in the loss of spawning habitat for some species. Impoundments created by these structures have altered the natural habitat from riverine to more lake-like water bodies. “De-watering” of the aquatic habitat that sometimes occurs due to atypical “hydro-peaking” dam operations leaves many benthic SGCN, particularly mussels, out of the water and exposed to the elements and predators. This can occur upstream or downstream of these structures. Existing dams located on fall lines may significantly alter the natural physicochemical regime of waters flowing downstream. The altered hydrologic regimes found below dams degrades the quality of habitat here for SGCN.

Zebra mussels that have devastated the Lake Champlain freshwater mussel community are a problem for rivers in this Lake Champlain tributaries. Adult zebra mussels have been found in the lower reaches of Otter Creek, Little Otter Creek, Lewis Creek, LaPlatte River and the Winooski River in past years. They are also present in Lake Bomoseen, whose outlet stream feeds into the Poultney River.

Desired Condition (SGCN Needs): These waters, along with Lake Champlain, support the greatest diversity of aquatic species found in the state. The larger rivers support the highest number of SGCN. Species include both year-round residents and those that use the rivers and streams primarily for spawning, development of young, or feeding. Minnows, freshwater mussels and snails, benthic fishes, and mammals are among those that utilize the Lake Champlain tributaries year-round, and often require a variety of habitats. Lake sturgeon, mooneye, greater redhorse, and possibly common mudpuppy are among those that depend on these rivers seasonally for reproduction. Others, such as map turtle, spiny softshell, northern watersnake, wood turtle, and bats use these waters for foraging, winter shelter, or other seasonal purposes.

 Gravel/cobble substrates that are free of loose silt are required by many of the riverine species that spawn here. Eggs in contact with excessive silt are not able to adequately absorb oxygen for development. The eastern sand darter requires silt-free sand for this purpose. Substrates also need to be stable in order to support many SGCN, particular benthic organisms like freshwater mussels, darters, hibernating spiny softshells, and nesting mudpuppies. This is often affected by stream hydrodynamics; that is, streams that are hydrodynamically imbalanced can have substrates that shift frequently and do not provide a firm footing or shelter for aquatic organisms that occur there. Small invertebrates are less abundant in silted-in or unstable stream bottoms, thus providing a reduced food source for their predators. Woody debris is an important habitat component in lower Lake Champlain tributaries, especially for aquatic insects. Historically, people removed trees and branches that fell into streams. Unfortunately, this removed the structure and habitat needed for many invertebrates and their predators, as well as basking habitat for turtles.

Two aquatic SGCN, the American eel and the Atlantic salmon, were historically able to ascend the fall line from downstream. The American eel did so to reach smaller waters upstream where the young eels would grow for several years before migrating back out to sea to spawn. Landlocked Atlantic salmon jumped the falls to reach the clean, coarse gravel substrates located upstream where they would spawn their eggs. With the construction of dams at or below the falls on all the major Lake Champlain rivers, much of the habitat needed for these two species was made unavailable to them. Reconnection of these fishes with this habitat would likely be beneficial to their long-term survival.

River otter and mink are susceptible to heavy metals and PCB's.

Fish Species of Greatest Conservation Need
in Lake Champlain Tributaries

High Priority

Lake Sturgeon (Acipenser fulvescens)
Eastern Sand Darter (Ammocrypta pellucida)
American Eel (Anguilla rostrata)
Quillback (Carpiodes cyprinus)
Muskellunge (Esox masquinongy)
American Brook Lamprey (Lampetra appendix)
Northern Brook Lamprey (Ichthyomyzon fossor)
Silver Redhorse (Moxostoma anisurum)
Greater Redhorse (Moxostoma valenciennesi)
Bridle Shiner (Notropis bifrenatus)
Blackchin Shiner (Notropis heterodon)
Blacknose Shiner (Notropis heterolepis)
Stonecat (Noturus flavus)
Channel Darter (Percina copelandi)
Sauger (Sander canadense)
Common Mudpuppy (Necturus maculosus)
River/stream Odonata group
Freshwater Mussels Group
Freshwater Snails Group

Medium Priority

Mottled Sculpin (Cottus bairdi)
Mooneye (Hiodon tergisus)
Silver Lamprey (Ichthyomyzon unicuspis)
Shorthead Redhorse (Moxostoma macrolepidotum)
Atlantic Salmon (landlocked) (Salmo salar)

SGCN Note: The SGCN invertebrate groups listed here contain numerous species. Sea lamprey is not a Species of Greatest Conservation Need in the Lake Champlain Basin. For more information about a specific Species of Greatest Conservation Need see that species' assessment summary in Appendix A