Simulation analysis of the ground-water flow system in the Portland Basin, Oregon and Washington

Evaluation of factors that influence estimated zones of transport for six municipal wells in Clark County, Washington

“…Clark County lies within a sediment-filled structural basin known as the Portland Basin. The hydrogeology of the Portland Basin has been the focus of several recent investigations by the USGS (McCarthy and Anderson, 1990;Swanson and others, 1993;Collins and Broad, 1993;Snyder and others, 1994;Morgan and McFarland, 1996;McFarland and Morgan, 1996) that form the foundation for much of the work presented here.…”

“…The overviews of the geology and hydrology of the Portland Basin presented in the following sections summarize more detailed descriptions in reports by (1) Swanson and others (1993), who discuss the thickness, extent, and lithology of hydrogeologic units in the basin, (2) McFarland and Morgan (1996), who describe the ground-water flow system of the basin, including its boundaries, hydraulic characteristics, and components of recharge and discharge, and (3) Morgan and McFarland (1996), who discuss the geology and hydrology as it relates to simulation of the ground-water flow system using numerical modeling.…”

“…Estimated recharge over the modeled area of the Portland Basin from these three sources ranges from 0 to 49 in/yr with a mean of 22 in/yr (Snyder and others, 1994). Irrigation return flow and losing streams may constitute locally important sources of seasonal recharge, but are insignificant on a regional scale Large capacity wells located near the Columbia River also can induce recharge from the river to the shallow alluvial aquifers (McCarthy and others, 1992;Morgan and McFarland, 1996).…”

“…Hydrogeologic units in the Portland Basin, as defined by Morgan and McFarland (1996) and used in their model of the ground-water flow system, may comprise one or more geologic units. From youngest to oldest the eight hydrogeologic units delineated within the basin were the:…”

Water and nutrient budgets for Vancouver Lake, Vancouver, Washington, October 2010-October 2012

“…Surficial geological material in the area primarily consists of recent alluvial deposits and the lake bottom consists mainly of unconsolidated fine sediment and virtually no macrophytes are present (Caromile and others, 2000). Detailed geological and hydrogeological information for the Vancouver Lake region is provided elsewhere (Mundorff, 1964;McFarland and Morgan, 1996;Morgan and McFarland, 1996;Parametrix, 2008;Sinclair and Kardouni, 2012). Being a large shallow lake, winds in the area may have an influence on the water quality of the lake, and it is suspected that wind-induced resuspension of sediments are a contributing factor to lake clarity and nutrient release, potentially fueling algal blooms in the study area.…”