Development projects sometimes require disturbance or alteration to existing stream corridors. Impacts may include piping some portion of the stream, crossing the stream with a bridge, filling the existing channel and rerouting the stream, or altering the natural vegetation on or near the stream bank. Recently we have seen an increase in the number of projects that involve impacting streams.

    In New York, permits are required for any alteration to protected stream channels or areas immediately adjacent. Additionally, the Army Corps of Engineers regulates streams as "Waters of the United States" and most have wetland areas associated with them.

    Permit applications often require supporting information on the biological and physical characteristics of the stream, and an estimate of the stream impacts resulting from proposed construction activities. These assessments can put the impacts into perspective and assist in the development of any required restoration. Supporting stream assessments can take many forms depending upon the nature of the proposed development and the water resource at issue.

    A physical characterization of the stream may include measurements of the stream channel at regular intervals and a series of cross-sections of the channel. It often includes measurements of water depth, current velocity, temperature, dissolved oxygen concentration, conductivity, and pH. Descriptions of stream substrate characteristics and the occurrence of riffles, runs, and pools are also important.

    TES fisheries biologists conduct stream fish surveys using a pulsed DC Electrofisher. Fish are stunned momentarily then netted and identified to species and measured. The fish are then returned unharmed to the stream. This equipment and technique provide a very efficient means of estimating fish population density and diversity in many types of streams.

    Sampling of macroinvertebrates (aquatic worms, insects, snails, and other invertebrates) is routinely used by the NYSDEC to evaluate the quality of streams throughout the state. TES uses the same "Rapid Biological Assessment" technique, including the Biological Assessment Profile (BAP) method, as the state. Macroinvertebrates are collected and preserved in the field. Organisms are identified and counted, and first several biological index values are calculated from the results. For example, Species Richness (SPP), Hilsenhoff Biotic Index (HBI), EPT Richness (EPT) and Percent Model Affinity (PMA) are the indices calculated for samples from stream riffle areas. These indices are then converted to a common scale of water quality using the BAP method. The final computational model used to numerically evaluate the water quality of the stream is specific to the type of stream habitat and the sampling method employed. Kick samples from riffles, net samples from slow, sandy streams, and Ponar samples from soft sediments each require that a unique model be applied to the indices, to permit normalizing each of the biological indices to this common scale of water quality. The numerical results allow the categorization of the stream as non-impacted, slightly impacted, moderately impacted, or severely impacted.

    A thorough stream assessment and detailed report provide important information to agency personnel to help them make decisions when reviewing permit applications. This information can also be employed as a baseline model in preparing a mitigation and monitoring plan, such as would be called for in the case of a stream relocation.

TES, Inc. 23 County Route 6, Suite A, Phoenix, NY 13135.  Tel: 315.695.7228  Fax: 315.695.3277

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