Meanders are winding bends in a stream channel; these features are characteristic of unconfined rivers. Occasionally, landowners channelize, or straighten, streams that meander through their property in order to, among other things, more quickly drain standing water from their land. Channel straightening, however, does more harm than good. It decreases the length of a river and increases its gradient, causing increased water velocity that leads to stream bed and stream bank erosion and slumping, channel widening and associated loss of a vegetated buffer, increased silt load, decreased food and cover for wildlife, increased flooding, and reduced in-stream habitat (pool/riffle) variation.
There are probably several hundred occurrences statewide. A few documented occurrences have good viability and are protected on public land or private conservation land. This community has statewide distribution, and includes a few high quality examples. The current trend of this community is probably stable for occurrences on public land, or declining slightly elsewhere due to moderate threats related to development pressure or alteration to the natural hydrology.
The number and miles of unconfined rivers in New York have probably remained stable in recent decades as a result of water quality regulations. Several examples have shown improvement in water quality in recent decades attributed to improved treatment of municipal and industrial waste (Bode et al. 1993).
The number and miles of unconfined rivers in New York are probably comparable to historical numbers, but the water quality of several of these rivers has likely declined significantly prior to the enforcement of water quality regulations (New York State Department of Environmental Conservation, Division of Water 2000).
Unconfined rivers are threatened by development and its associated run-off (e.g., residential, agricultural, roads, bridges), recreational overuse (e.g., ATVs, intensive fish stocking and removal, motor boating), and habitat alteration in the adjacent landscape (e.g., excessive logging, instream gravel mining, pollution run-off). In addition, alteration to the natural hydrology (e.g., impoundments, ditching, stream channelization, dredging, canals), spread of non-native invasive species, and reduction in water quality (e.g., siltation, trash, turbidity, septic/nutrient run-off) are threats to unconfined river communities. Agricultural activity is the most frequently cited nonpoint source of water quality impact and use impairment to New York State rivers (New York State Department of Environmental Conservation, Division of Water 2000).
Where practical, establish and maintain a riparian buffer to reduce storm-water, pollution, and nutrient run-off, while simultaneously capturing sediments before they reach the river. Buffer width should take into account the erodibility of the surrounding soils, slope steepness, and current land use. If possible, minimize the number and size of impervious surfaces in the surrounding landscape. Avoid habitat alteration within the river and surrounding landscape. For example, roads should not be routed through the riparian buffer area. If the river must be crossed, then bridges and boardwalks are preferred over filling and culverts. Restore past impacts, such as removing obsolete impoundments and ditches in order to restore the natural hydrology. Prevent the spread of invasive exotic species into the river through appropriate direct management, and by minimizing potential dispersal corridors.
When considering road construction and other development activities, minimize actions that will change what water carries and how water travels to this community, both on the surface and underground. Water traveling over-the-ground as runoff usually carries an abundance of silt, clay, and other particulates during (and often after) a construction project. While still suspended in the water, these particulates make it difficult for aquatic animals to find food; after settling to the bottom of the system, they bury small plants and animals and alter the natural functions of the community in many other ways. Thus, road construction and development activities near this community type should strive to minimize particulate-laden run-off into this community. Water traveling on the ground or seeping through the ground also carries dissolved minerals and chemicals. Road salt, for example, is becoming an increasing problem both to natural communities and as a contaminant in household wells. Fertilizers, detergents, and other chemicals that increase the nutrient levels in wetlands cause algal blooms and eventually an oxygen-depleted environment in which few animals can live. Herbicides and pesticides often travel far from where they are applied and have lasting effects on the quality of the natural community. So, road construction and other development activities should strive to consider: 1. how water moves through the ground, 2. the types of dissolved substances these development activities may release, and 3. how to minimize the potential for these dissolved substances to reach this natural community.
Survey for occurrences statewide to advance documentation and classification of unconfined rivers. A statewide review of unconfined rivers is desirable. Continue searching for large rivers in good condition (A- to AB-ranked).
There is a need to research the composition of confined rivers statewide in order to characterize variations. In addition, there is a need to collect sufficient quantitative data to support the recognition of several distinct types of confined rivers based on composition and by ecoregion.
Unconfined rivers are widespread throughout the state north of the North Atlantic Coast Ecoregion and appear to be concentrated in the non-mountainous areas of upstate New York. This river community is likely represented by different variants corresponding to major watersheds and ecoregions.
This broadly-defined community may be worldwide. Examples with the greatest biotic affinities to New York occurrences are suspected to span north to southern Canada, west to Minnesota, southwest to Indiana and Tennessee, and southeast to Georgia.
Unconfined rivers are large, quiet, sections of a riverine complex where there are no distinct riffles. They have a very low average gradient and are found typically in the lowermost stream reaches. They are characterized by considerable deposition with a relatively minor amount of erosion. Occurrences often have a floodplain forest bordering large parts of their length, associated meanders, and good levee development. They usually have fine substrates, typically silty soils associated with a depositional environment, obtain high levels of nutrients from surrounding wetlands, and have a large component of run microhabitat. Species assemblages characteristic of pools and soft bottoms dominate the community and many of the fishes are anadromous.
Unconfined rivers have clearly distinguished meanders and are located in unconfined valleys. These communities are typically more than about 4 m deep, generally greater than 2 m wide, and have high low flow discharge. Any riffles are typically localized and occur at low abundance; water is typically turbid and poorly aerated. Characteristic fishes include suckers (Catostomids), redhorses (Moxostoma spp.), sturgeon (Acipenser spp.), and shad (Alosa spp.). Although the middle of a main channel stream is too deep for aquatic macrophytes to occur, the shallow shores and backwaters typically have rooted macrophytes. Mosses in the genus Fontinalis are characteristic of shallow areas. Two exotic weeds, Eurasian milfoil (Myriophyllum spicatum) and water chestnut (Trapa natans) may also occur along shores and backwaters. Plankton assemblages may be abundant.
Known examples of this community have been found at elevations between 1,505 feet and 1,733 feet.
Unconfined rivers are scenic year-round, but have greater flow in spring and early summer. Mid- to late summer is a good time to look for the diverse array of aquatic macroinvertebrates living in the streambed.
Bode, R.W., M.A. Novak, and L.E. Abele. 1993. Twenty year trends in water quality of rivers and streams in New York State based on macroinvertebrate data 1972-1992. New York Department of Environmental Conservation, Division of Water, Albany, NY.
Edinger, G. J., D. J. Evans, S. Gebauer, T. G. Howard, D. M. Hunt, and A. M. Olivero (editors). 2014. Ecological Communities of New York State. Second Edition. A revised and expanded edition of Carol Reschke’s Ecological Communities of New York State. New York Natural Heritage Program, New York State Department of Environmental Conservation, Albany, NY. https://www.nynhp.org/ecological-communities/
Edinger, Gregory J., D.J. Evans, Shane Gebauer, Timothy G. Howard, David M. Hunt, and Adele M. Olivero (editors). 2002. Ecological Communities of New York State. Second Edition. A revised and expanded edition of Carol Reschke's Ecological Communities of New York State. (Draft for review). New York Natural Heritage Program, New York State Department of Environmental Conservation. Albany, NY. 136 pp.
New York Department of Environmental Conservation, Division of Water. 2000. New York State water quality 2000. October 2000. New York Department of Environmental Conservation, Division of Water, Albany, NY.
New York Natural Heritage Program. 2021. New York Natural Heritage Program Databases. Albany, NY.
New York Natural Heritage Program. No date. Field forms database: Electronic field data storage and access for New York Heritage ecology, botany, and zoology. New York Natural Heritage Program, New York State Department of Environmental Conservation. Albany, NY.
Reschke, Carol. 1990. Ecological communities of New York State. New York Natural Heritage Program, New York State Department of Environmental Conservation. Latham, NY. 96 pp. plus xi.
Smith, C.L. 1985. The Inland Fishes of New York State. New York State Department of Environmental Conservation. Albany, NY. 522pp.
This guide was authored by: Gregory J. Edinger
Information for this guide was last updated on: July 16, 2021
Please cite this page as:
New York Natural Heritage Program. 2021. Online Conservation Guide for Unconfined river. Available from: https://guides.nynhp.org/unconfined-river/. Accessed July 29, 2021.