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I I I I I I I I I I I I I I I I I I I maps of this area indicate that the river channel had changed course several times prior to channelization. Remnant depressional areas and drainage patterns from the previous overbank channels and backwater systems are evident. These areas presently hold water seasonally and during high-water events. Approximately 1.5 miles of the main Missouri River channel (river miles 651 to 649.5) border the western side of the project site. Confining the flow of the Missouri River has resulted in a narrower and deeper river channel and has led to the aggradation of sediments on the adjacent floodplains. The soils of the project site are primarily of the Sarpy-Albaton-Carr Association and may contain portions of the Haynie-Onawa-Albaton association (USDA 1976). The Sarpy-Albaton- Carr Association consists of excessively drained to poorly drained, nearly level to gently undulating, stratified sandy, loamy and clayey soils on bottomlands of the Missouri River. The Albaton-Haynie-Onawa Assoication consists of deep, nearly level, moderately well-drained to poorly drained silty and clayey soils that formed in alluvium on bottomlands and are subject to flooding (Exhibit 3). b. Water Quality: The water quality of the backwater areas at the California Bend site is likely to be consistent with its primary water source, the Missouri River. Because the area is surrounded by agricultural land, the presence of residual pesticides and herbicides from runoff may be expected (pAS 1994). If there is any overflow from the agricultural drainage ditch along the north boundary of the site during flood events, this may contribute additional amounts of pesticides and herbicides. The Preliminary Assessment Screening conducted in June 1994 and the site visit in August 1994 did not reveal any evidence of stressed flora or fauna suggesting that excessive application of, or negligent storage and use of, agricultural chemicals is not likely occurring. The levels of residual pesticides and herbicides which would normally be found in an agricultural community would pose a very low potential for adverse effects to habitats on the site. High temperatures and low dissolved oxygen levels probably occur in many areas within the backwater during the summer months due to the shallow nature of the water and the lack of flow and mixing with the Missouri River except during high stages. These conditions would be expected in backwater areas with little or no hydraulic connection to the main stem of the Missouri River or its tributaries. c. Air Quality: Major sources of suspended particulate matter and pollution are from agricultural and boating activities adjacent to the project site. There have been no violations of the National Ambient Air Quality Standards (NAAQS) in Harrison County, Iowa or in the neighboring Washington County, Nebraska. The project area is in attainment of NAAQS according to the Iowa Department of Natural Resources and the Nebraska Department of Natural Resources. d. Noise: Sources of noise in and around the project site result from recreational boating, commercial barges, hunting and agricultural activities. These activities are seasonal. In the spring and fall there is an increased use of tractors and trucks on farms near the project 9