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Research about Washington

Source-linked reports with geographic coverage including Washington.

At least 1,243 records · Page 69Linked to original sources
USGS1997

Distribution of fish, benthic invertebrate, and algal communities in relation to physical and chemical conditions, Yakima River basin, Washington, 1990

Biological investigations were conducted in the Yakima River Basin, Washington, in conjunction with a pilot study for the U.S. Geological Survey's National Water-Quality Assessment Program. Ecological surveys were conducted at 25 sites in 1990 to (1) assess water-quality conditions based on fish, benthic invertebrate, and algal communities; (2) determine the hydrologic, habitat, and chemical factors that affect the distributions of these organisms; and (3) relate physical and chemical conditions to water quality. Results of these investigations showed that land uses and other associated human activities influenced the biological characteristics of streams and rivers and overall water-quality conditions. Fish communities of headwater streams in the Cascades and Eastern Cascades ecoregions of the Yakima River Basin were primarily composed of salmonids and sculpins, with cyprinids dominating in the rest of the basin. The most common of the 33 fish taxa collected were speckled dace, rainbow trout, and Paiute sculpin. The highest number of taxa (193) was found among the inverte- brates. Insects, particularly sensitive forms such as mayflies, stoneflies, and caddisflies (EPT--Ephemeroptera, Plecoptera, and Trichoptera fauna), formed the majority of the invertebrate communities of the Cascades and Eastern Cascades ecoregions. Diatoms dominated algal communities throughout the basin; 134 algal taxa were found on submerged rocks, but other stream microhabitats were not sampled as part of the study. Sensitive red algae and diatoms were predominant in the Cascades and Eastern Cascades ecoregions, whereas the abundance of eutrophic diatoms and green algae was large in the Columbia Basin ecoregion of the Yakima River Basin. Ordination of physical, chemical, and biological site characteristics indicated that elevation was the dominant factor accounting for the distribution of biota in the Yakima River Basin; agricultural intensity and stream size were of secondary importance. Ordination identified three site groups and three community types. Site groups consisted of (1) small streams of the Cascades and Eastern Cascades ecoregions, (2) small streams of the Columbia Basin ecoregions, and (3) large rivers of the Cascades and Columbia Basin ecoregions. The small streams of the Columbia Basin could be further subdivided into two groups--one where agricultural intensity was low and one where agricultural intensity was moderate to high. Dividing the basin into these three groups removed much of the influence of elevation and facilitated the analysis of land-use effects. Community types identified by ordination were (1) high elevation, cold-water communities associated with low agricultural intensity; (2) lower elevation, warm-water communities associated with low agricultural intensity, and (3) lower elevation, warm-water communities associated with moderate to high agricultural intensity. Multimetric community condition indices indicated that sites in the Cascades and Eastern Cascades site group were largely unimpaired. In contrast, all but two sites in the Columbia Basin site group were impaired, some severely. Agriculture (nutrients and pesticides) was the primary factor responsible for this impairment, and all impaired sites were characterized by multiple indicators of impairment. Three sites (Granger Drain, Moxee Drain, and Spring Creek) had high levels of impairment. Sites in the large-river site group were moderately to severely impaired downstream from the city of Yakima. High levels of impairment at large-river sites corresponded with high levels of pesticides in fish tissues and the occurrence of external anomalies.

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USGS1997

Ambient quality of ground water in the vicinity of Naval Submarine Base Bangor, Kitsap County, Washington, 1995

A study of the ambient ground-water quality in the vicinity of Naval Submarine Base (SUBASE) Bangor was conducted to provide the U.S. Navy with background levels of selected constituents. The Navy needs this information to plan and manage cleanup activities on the base. During March and April 1995, 136 water-supply wells were sampled for common ions, trace elements, and organic compounds; not all wells were sampled for all constituents. Man-made organic compounds were detected in only two of fifty wells, and the sources of these organic compounds were attributed to activities in the immediate vicinities of these off-base wells. Drinking water standards for trichloroethylene, iron, and manganese were exceeded in one of these wells, which was probably contaminated by an old local (off-base) dump. Ground water from wells open to the following hydrogeologic units (in order from shallow to deep) was investigated: the Vashon till confining unit (Qvt, three wells); the Vashon aquifer (Qva, 54 wells); the Upper confining unit (QC1, 16 wells); the Permeable interbeds within QC1 (QC1pi, 34 wells); and the Sea-level aquifer (QA1, 29 wells).The 50th and 90th percentile ambient background levels of 35 inorganic constituents were determined for each hydrogeologic unit. At least ten measurements were required for a constituent in each hydrogeologic unit for determination of ambient background levels, and data for three wells determined to be affected by localized activities were excluded from these analyses. The only drinking water standards exceeded by ambient background levels were secondary maximum contaminant levels for iron (300 micrograms per liter), in QC1 and QC1pi, and manganese (50 micrograms per liter), in all of the units. The 90th percentile values for arsenic in QC1pi, QA1, and for the entire study area are above 5 micrograms per liter, the Model Toxics Control Act Method A value for protecting drinking water, but well below the maximum contaminant level of 50 micrograms per liter for arsenic. The manganese standard was exceeded in 38 wells and the standard for iron was exceeded in 12 wells. Most of these wells were in QC1 or QC1pi and had dissolved oxygen concentrations of less than 1 milligram per liter and dissolved organic carbon concentrations greater than 1 milligram per liter. The dissolved oxygen concentration is generally lower in the deeper units, while pH increases; the recommended pH range of 6.5-8.5 standard units was exceeded in 9 wells. The common-ion chemistry was similar for all of the units.

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USGS1996

Tectonics and seismicity of the southern Washington Cascade range

Geophysical, geological, and seismicity data are combined to develop a transpressional strain model for the southern Washington Cascades region. We use this model to explain oblique fold and fault systems, transverse faults, and a linear seismic zone just west of Mt. Rainier known as the western Rainier zone. We also attempt to explain a concentration of earthquakes that connects the northwest-trending Mount St. Helens seismic zone to the north-trending western Rainier zone. Our tectonic model illustrates the pervasive effects of accretionary processes, combined with subsequent transpressive forces generated by oblique subduction, on Eocene to present crustal processes, such as seismicity and volcanism.

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USGS1996

Earthquake-induced burial of archaeological sites along the southern Washington coast about A.D. 1700

Although inhabited by thousands of people when first reached by Europeans, the Pacific coast of southern Washington has little recognized evidence of prehistoric human occupation. This apparent contradiction may be explained partly by geologic evidence for coastal submergence during prehistoric earthquakes on the Cascadia subduction zone. Recently discovered archaeological sites, exposed in the banks of two tidal streams, show evidence for earthquake-induced submergence and consequent burial by intertidal mud about A.D. 1700. We surmise that, because of prehistoric earthquakes, other archaeological sites may now lie hidden beneath the surfaces of modern tidelands. Such burial of archaeological sites raises questions about the estimation of prehistoric human population densities along coasts subject to earthquake-induced submergence.

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USGS1996

Simulating secondary succession of elk forage values in a managed forest landscape, western Washington

Modern timber management practices often influence forage production for elk (Cervus elaphus) on broad temporal and spatial scales in forested landscapes. We incorporated site-specific information on postharvesting forest succession and forage characteristics in a simulation model to evaluate past and future influences of forest management practices on forage values for elk in a commercially managed Douglas fir (Pseudotsuga menziesii, PSME)-western hemlock (Tsuga heterophylla, TSHE) forest in western Washington. We evaluated future effects of: (1) clear-cut logging 0, 20, and 40% of harvestable stands every five years; (2) thinning 20-year-old Douglas fir forests; and (3) reducing the harvesting cycle from 60 to 45 years. Reconstruction of historical patterns of vegetation succession indicated that forage values peaked in the 1960s and declined from the 1970s to the present, but recent values still were higher than may have existed in the unmanaged landscape in 1945. Increased forest harvesting rates had little short-term influence on forage trends because harvestable stands were scarce. Simulations of forest thinning also produced negligible benefits because thinning did not improve forage productivity appreciably at the stand level. Simulations of reduced harvesting cycles shortened the duration of declining forage values from approximately 30 to 15 years. We concluded that simulation models are useful tools for examining landscape responses of forage production to forest management strategies, but the options examined provided little potential for improving elk forages in the immediate future.

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USGS1996

The southern Whidbey Island fault: An active structure in the Puget Lowland, Washington

Information from seismic-reflection profiles, outcrops, boreholes, and potential field surveys is used to interpret the structure and history of the southern Whidbey Island fault in the Puget Lowland of western Washington. This northwest-trending fault comprises a broad (as wide as 6–11 km), steep, northeast-dipping zone that includes several splays with inferred strike-slip, reverse, and thrust displacement. Transpressional deformation along the southern Whidbey Island fault is indicated by along-strike variations in structural style and geometry, positive flower structure, local unconformities, out-of-plane displacements, and juxtaposition of correlative sedimentary units with different histories. The southern Whidbey Island fault represents a segment of a boundary between two major crustal blocks. The Cascade block to the northeast is floored by diverse assemblages of pre-Tertiary rocks; the Coast Range block to the southwest is floored by lower Eocene marine basaltic rocks of the Crescent Formation. The fault probably originated during the early Eocene as a dextral strike-slip fault along the eastern side of a continental-margin rift. Bending of the fault and transpressional deformation began during the late middle Eocene and continues to the present. Oblique convergence and clockwise rotation along the continental margin are the inferred driving forces for ongoing deformation. Evidence for Quaternary movement on the southern Whidbey Island fault includes (1) offset and disrupted upper Quaternary strata imaged on seismic-reflection profiles; (2) borehole data that suggests as much as 420 m of structural relief on the Tertiary-Quaternary boundary in the fault zone; (3) several meters of displacement along exposed faults in upper Quaternary sediments; (4) late Quaternary folds with limb dips of as much as ≈9°; (5) large-scale liquefaction features in upper Quaternary sediments within the fault zone; and (6) minor historical seismicity. The southern Whidbey Island fault should be considered capable of generating large earthquakes (M s ≥7) and represents a potential seismic hazard to residents of the Puget Lowland.

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USGS1996

The southern limit of Cordilleran ice in the Colville and Pend Oreille valleys of northeastern Washington during the Late Wisconsin glaciation

The southern limit of the lobes of the Cordilleran ice sheet in the Colville and Pend Oreille valleys of northeastern Washington during the Late Wisconsin (Fraser) glaciation has been placed at widely different positions by various investigators. The confusion that resulted in these different positions is due to the fact that both lobes, at times, terminated in glacial lakes and much of the terminal area of the Pend Oreille River lobe was swept by floods from glacial Lake Missoula. Evidence, presented in this paper, of the southern limit of these two lobes during the Late Wisconsin glaciation consists of ( i ) the southern limit of Late Wisconsinan till, ( ii ) the southern limit of lateral meltwater channels, ( iii ) meltwater channels whose headward areas coincide with the southern limit of Late Wisconsinan till, and ( iv ) reconstructed ice-surface profiles. This evidence suggests that the southern limit of the Colville lobe is represented by a moraine near the town of Springdale, whereas that of the Pend Oreille River lobe is near the town of Newport. The timing and extent of Late Wisconsinan deglaciation in the Colville Valley are provided by radiocarbon ages and Late Pleistocene tephras at sites upglacier from thfe terminal position. These data demonstrate that the Colville lobe had retreated at least 50 km by about 12 450 BP. In the Pend Oreille Valley, the presence of a Glacier Peak tephra layer near the town of lone indicates that the Pend Oreille River lobe had retreated at least 70 km prior to deposition of the tephra.

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