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Investigation of impacts associated with modifying East Sand Island to prevent nesting of double-crested cormorants
| Content Provider | Semantic Scholar |
|---|---|
| Author | Pevey, Kimberly Collins McAlpin, T. O. Moritz, Hans R. |
| Copyright Year | 2015 |
| Abstract | The U. S. Army Engineer District, Portland, is conducting an alternative analysis under an Environmental Impact Statement to determine a preferred approach to permanently modify or eliminate habitat for doublecrested cormorants on East Sand Island in the Columbia River. The goal of the alternative analysis is to determine how to reduce/eliminate the habitat for the cormorants and correspondingly increase the survivability of the out-migrating salmonids without impacting the overall behavior of the system, including the stability of the island and navigation. One proposal to reduce/eliminate cormorant habitat on East Sand Island is to cause the parts of the island used by the birds to become subtidal or intertidal so that the island will not be used for nesting or roosting. Hydrodynamic impacts associated with proposed system alterations to East Sand Island are investigated. An Adaptive Hydraulics numerical model of the Lower Columbia River produces water levels, velocities, shear stresses, and inundation information for existing conditions and one alternative condition in and around the study area. A base versus alternative plan analysis was conducted by simulating the existing and proposed conditions for two time periods, May (high river flow) and August (low river flow) 2009. Comparisons of the existing and proposed simulations indicate the differences between the water surface elevation, velocity, and bed shear stress will be small. The system as a whole should experience minimal changes. Based on the simulation results, the lagoons will be inundated approximately 40%-60% of the time. The May 2009 time period has slightly higher percent inundated values than the August 2009 time period. Overall, it appears from this analysis that the lagoon/atoll design will produce minimal impacts to the surrounding environment in terms of bed shear stress and based on the inundation times, will likely reduce cormorant nesting habitat. DISCLAIMER: The contents of this report are not to be used for advertising, publication, or promotional purposes. Citation of trade names does not constitute an official endorsement or approval of the use of such commercial products. All product names and trademarks cited are the property of their respective owners. The findings of this report are not to be construed as an official Department of the Army position unless so designated by other authorized documents. DESTROY THIS REPORT WHEN NO LONGER NEEDED. DO NOT RETURN IT TO THE ORIGINATOR. ERDC/CHL TR-15-16 iii |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://erdc-library.erdc.dren.mil/xmlui/bitstream/handle/11681/7323/ERDC-CHL-TR-15-16.pdf?isAllowed=y&sequence=1 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
