The National Park Service (NPS) has implemented a plan to reclaim and restore disturbed streams and floodplains in the Kantishna area of Denali National Park and Preserve (DNPP) that have been impacted by placer mining operations. The overall purpose of the NPS’s plan is to restore a natural appearance to the disturbed drainages, restore aquatic habitat, assist with natural revegetation, recontour tailings piles, and reconstruct channels and floodplains to original flood capacity and function.
OASIS was tasked with helping to mitigate the multifaceted and adverse ecological effects of past placer mining. By way of example, mining operations had involved moving alluvial gravel to access and process the concentrated ore, which eliminated the physical structure of the stream and riparian ecosystems in some areas and degraded overall water quality, in general. Many of the characteristics of stream systems were no longer present.
OASIS recommended and oversaw the recontouring of tailings piles and the reconstruction of stream channels and floodplains, which involved the alteration of the existing active stream channels. OASIS also provided design and construction oversight, pre- and post-construction surveys, and field-design modifications in four separate drainages of the Kantishna area over the course of two years. During stream bank reconstruction, OASIS utilized fabric-encapsulated soil lifts, Coir-log lifts and rock vanes, and grade control structures, such as rock weirs, in order to create stable bank structures. Wetland bank and floodplain habitats were reintroduced to provide water quality and fish habitat improvements.
As a result of these efforts, more than eight miles of stream habitat was improved. Floodplain revegetation efforts included collecting and spreading native seed, installing vegetative transplants and cuttings, fertilizing, and loosening and roughening of soils. Additionally, in 2010, Caribou Creek was removed from the CWA section 303(d) list and now meets water quality standards.