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Dames & Moore, 1999 - USDA Forest Service

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discussions of the 1992 data have not been included in this investigation. The following sections describe<br />

specific sampling objectives and procedures designed io discern the causes of conditions in Railroad<br />

Creek as they existed during the fall of 1997.<br />

The general objectives of this program are to determine why fish and benthic, macroinvenebrate<br />

populations in Railroad Creek downstream of the Site appear to be degraded relative to populations<br />

evaluated upstream and to identify injuries to natural resources. The objectives of the ecological surveys<br />

were to:<br />

Distinguish between potential chemical and physical influences on the creek<br />

Preliminarily identify potential exposure pathways<br />

Identify where chemical exposures and adverse effects may have occurred<br />

Quantify the magnitude of the effects of those exposures<br />

Identify potentially affected resources<br />

The specific hypotheses tested were:<br />

There is no difference between populations of fish and benthos between potentially<br />

affected and reference areas.<br />

Differences observed between populations of fish and benthos in potentially affected and<br />

reference areas are due to physical impacts.<br />

Differences observed between populations of fish and benthos in potentially affected and .<br />

reference areas are due to chemical impacts.<br />

Sampling activities described herein were designed to test these hypotheses. The aquatic ecological<br />

assessment program consists of two phases. Phase I included the identification of aquatic biota sampling<br />

locations (reference and potentially affected) and investigation of the potential for rare, threatened, or<br />

endangered species to inhabit the Holden Mine area or the Railroad Creek drainage. Phase I1 included the<br />

collection of data necessary to address the objectives listed above. Additionally, a qualitative survey of<br />

terrestrial species was conducted during Phase 11. The Phase I1 field program included: (1) assessing<br />

aquatic habitat conditions of Railroad Creek and reference areas, (2) assessing the benthic<br />

macroinvertebrate communities within Railroad Creek and reference areas, and (3) assessing fish<br />

communities within Railroad Creek and reference areas.<br />

3.9.1.2 Phase I<br />

Phase I ecological tasks included the identification of aquatic sample locations and the preliminary<br />

investigation of the,potential for threatened and endangered species to occur in the vicinity of the Site.<br />

These tasks provided the basis for pursuing the Phase I1 field investigations.<br />

Site Sample Locations Selection<br />

In order to allow a comparison of historical and recent data, the 1997 aquatic biota sampling and habitat<br />

analysis locations were selected as near as practically possible to the locations sampled by Pacific<br />

Northwest Laboratory (PNL) during 1989 and 1991. The final selection of sampling locations was based<br />

~:\w~dala\005\rc~o~~olden~2\ri~-0,doe<br />

17693-005-019Uuly 19. <strong>1999</strong>;2:07 PM;DRAFT FINAL RI REPORT

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