Source of Sediment Infilling Black Lake, Alaska

NOTICE OF INTENT TO AWARD SOLE SOURCE: U. S. Army Corps of Engineers Alaska District, Elmendorf AFB, AK intends to award a sole source purchase order to the University of Iowa, to determine the source of sediment infill to Blake Lake, Located near Chignik, Alaska. Water depth in the lake has decreased significantly during the last several decades, with major impacts to salmon production. Identifying the source of infilling is needed in order to make management decisions and design specifications for any future water-control structure. Dated marker horizons in sediment cores will be used to quantify the origin of sediment that has accumulated at spatially distributed sites across the lake. This purchase order will be made under Other Than Full and Open Competition as authorized by FAR 6.302-1(a)(2)(ii). High magnitude events are geomorphologically critical because they affect stream morphology and lake bed sediment stratigraphy. The Alec River (AR) - Black Lake (BL) watershed on the Alaskan Peninsula is one such system where we can see the effects of high magnitude events and the resulting sediment delivery to the lake over time (Ruggerone, 1994). Buffington (2002) and Elhakeem and Papanicolaou (2008) have documented changes to the AR-BL system, specifically the BL geomorphology (Figure 1), which have resulted from several large magnitude events that occurred between 1960 and 2000. Overall, these changes in lake geometry have severely threatened the highly productive salmon population of the system. In hopes of abating the deteriorating conditions of the AR-BL system, the US Army Corps of Engineers (COE) and the Chignik Regional Aquaculture Association (CRAA) have identified the following four priority objectives that are needed to evaluate the lake sedimentation issues and facilitate restoration efforts in the AR-BL system: Objective 1: Quantify the rate of sediment infilling in BL since the 1960s. Objective 2: Determine the variability of infilling between and within the two BL basins since the 1960s. Objective 3: Quantify the development rate of the spit since the 1960s and identify the source of this sediment. Objective 4: Identify the primary sources of sediment (e.g., floodplain, bank, and upland) to BL since the 1960s and quantify their relative contributions. Research will be conducted in order to address these priorities through the collection of multiple sediment cores from BL and surface samples from the upland soils, channel banks, and floodplain of the AR. We will then use isotopic tracers to quantify both the infilling rate of sediment in BL and differentiate the relative proportions of the various sediment sources that contribute to the system. The anticipated award date is June 15, 2010. This notice is neither a request for competitive proposals nor a solicitation of offers.