Design Considerations

Seagrass - Salt Marsh - Anadromous Fish Habitat

Anadromous Fish Habitat

Potential Obstacles to Restoration | Equipment Sources and Contacts

Potential Obstacles to Restoration
Industrialization and urbanization present special problems for dam removal. Contaminated sediments that have accumulated over decades upstream of dams located in densely populated or industrialized watersheds may be subject to release and downstream transport if certain dams are removed or breached. For example, removal or breaching was proposed for an obsolete dam located on the Woonasquatucket River in Providence. However, the discovery of dioxin-contaminated sediments upstream has prompted reconstruction of the dam, to prevent the release of contaminants downstream (USEPA 2002).

In non-contaminated waters, dam removal or breaching may result in undesired changes in sedimentation rates, and channel scour, which may induce erosion of stream banks. These conditions may be temporary, immediately following the process, or they may persist, resulting in permanent alteration of downstream habitats (Connecticut River Watershed Council, Inc. 2000).

The effect of dam removal or breaching on rare species must be considered in fish run restoration projects. Threatened or endangered fish or invertebrate species, if present downstream of an impediment to be modified or eliminated, may be unable to persist in the presence of changing water levels or downstream flow rates. Threatened or endangered species present upstream of the impediment may be unable to adapt to lower water levels and/or increased channel velocity resulting from removal or breaching of an impediment (Connecticut River Watershed Council, Inc. 2000).

As with other restoration projects in the coastal zone, dam removal or breaching must consider the effect on cultural resources. Many of the dams in Rhode Island date back to early colonial times, and may represent significant cultural resources. Native American sites are particularly abundant in the vicinity of rivers and streams, and could be subject to disturbance during a dam removal or fishway construction project. A professional archaeologist or agency cultural resources specialist should be a participant on any technical advisory team tasked with planning and designing a fish run restoration project in Narragansett Bay tributaries.

Fishway construction projects must consider and allow for the downstream passage of juvenile fish as well as spawning adults. In some cases, multiple fishways must be incorporated into the design to accommodate both juvenile and adult life stages.

Equipment Sources and Contacts
Local experts and fisheries biologists can be accessed at state environmental resource agencies and at academic research institutions. Some of these include the Department of Environmental Management Division of Fish and Wildlife, the Narragansett Bay Estuary Program, and the NOAA National Marine Fisheries Service Restoration Center. Contacts for these groups and others are available from this Web site.

Many companies specialize in the manufacture and sale of environmental monitoring equipment used in conducting baseline and monitoring studies of fishery restoration projects. Equipment includes seine nets, gill nets, fish counters, and water quality monitoring supplies.

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References

Connecticut River Watershed Council, Inc. 2000. A fishway for your stream: Providing fish passage around dams in the Northeast. The Connecticut River Watershed Council, Inc., Easthampton, Massachusetts. Visit http://www.ctriver.org/ to order copies of this publication.

U.S. Environmental Protection Agency (USEPA). 2002. "Woonasquatucket River Overview: A river on the rebound" Web page (http://www.epa.gov/region01/ra/woonas/). Boston, Massachusetts.

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