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JUL-29-94 FRI 1531 ~ FAX N0. 303 94775 P, 03 alteration of these habitats. Additional information shall be required regazding the hydrology and the slow of water through the pediment. The wetlands that exist along the colluvial slopes are the result of a shallow aquifer drainage from the Rocky Flats Alluvium. Water stored in the alluvium does not penetrate the underlying claystone bedrock. At this contact, the alluvium water moves horizontally and discharges to the surface along preferential flow paths. In other areas sandstone lenses may subcrop below the Rocky Fiats Alluvium. These bedrock sandstone lenses may be recharged from the Rocky Flats Alluvium and have the potential to transmit water to the colluvial slopes in a similaz manner- The resulting seeps produce wetlands of excellent quality and habital importance along the colluvial slopes. Ren:toval of the Rocky Flats Alluvium as part of the WAI mining expansiott has the potential to dew•ater the wetlands that exist along the colluvial slopes by removing the subsurface flow paths- In order to fully understand the impacts that mining might have on wetlands located along the colluvial slopes in Rock Creek, WAI should thoroughly investigate the hydraulic connection between the seeps and the alluvium. The investigation should include changes in the ground water hydrology as a function of season, heterogeneity of the substrate, and geomorphology. 1n addition, background sites for Rocky Flats environmental monitoring need to be maintained for 3 - 5 years anal the Environmental Protection Agency and the Colorado Department of Health approve data collected and added samples can be obtained to fill gaps in the data. Western Aggregates and the Department of Energy at Rocky Flats will be holding a joint meeting with hydrologists and concerned/interested parties August 5, 1994. The purpose of this meeting is the presentation and discussion' of the hydrologic concerns and potential impacts. Hig;ttly Sensitive Habitats The: Rock Creek area comprises a unique interspersion of riparian, wetland and shrub habitats. It is anticipated that the collapse of any one of these habitats will have a rippling effect on the oth~xs. Interruption of the ground water flows could destroy the wetlands in Rock Creek, and has the potential to reduce or stop the ground water fed base flow of the entire creek. It is imperative that: the hydrology of the area be maintained either naturally or manually. Wetland Banking should be a tradeoff considered at the time of reclamation. In addition, Western Aggregates should consult with the U.S. Fish and Wildlife Service to ensure their compliance with the Endangered Species Act (Act). This Act is designed to protect plant and. animal resources from adverse effects resulting from development. The act provrdes protection not only to individual plant and animal species but also to the ecosystems on which they depend. There is a significant population of a C-2 candidate species, Preble's Meadow Juntping Mouse (Zapus hudsonius preblee~, known to exist in the Rock Creek area. This area may also be used for forage by listed birds of prey. It is within the spirit of the Act that Federal agencies plan their activities and manage natural resources with regard for candidate species. In addition, the Ecology Staff has supervised surveys, as required by U.S. Fish and Wildlife on the Utr: Ladies =tresses orchid. The initial phase of the survey work will be completed in ] 994, but surveys are required at three year intervals after 1994. The Rock Creek area contains substantial areas of jurisdictional wetlands. Additional documentation is required in classification and mapping of the wetlands and subsequent handling of these by the Army Corps of Engineers if the wetlands are to be altered in any way.