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During the fiscal year 1934-35, although directly appropriated funds for the support of the Survey's regular activities have been at a low ebb (see details in later pages), these have been augmented by substantial allocations for closely related work made by the Public Works Administration.
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Basically important in the general program of conservation and development were the results of the Geological Survey's work during the fiscal year 1938. Investigations of the Nation's mineral and water supplies were conducted with all possible vigor and dispatch, thousands of square miles were surveyed for topographic maps, and technical supervision was given to prospecting, mining, and producing operations on public and Indian lands. This work was accomplished through the use of the regularly appropriated funds, the co-operative funds from States, counties, and municipalities, the funds transferred from other departments of the Government for types of work within the Survey's field, and the emergency funds derived chiefly from the Public Works Administration and devoted largely to mapping of various types and to studies of floods. The aggregate expenditures amounted to $5,248,000, which was 265,000 less than the amount expended during the preceding year.
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The U.S. Geological Survey, in cooperation with the National Park Service, analyzed water and sediment chemistry, benthic macroinvertebrate assemblages, fish and amphibian assemblages, fish and invertebrate tissues, instream habitat characteristics, and sediment heterogeneity at 10 stream sites within Whiskeytown National Recreation Area, Shasta County, California, during August 2020, 2 years after the Carr Fire. The post-Carr Fire data were compared to available pre-Carr Fire data to help determine if there have been wildfire-induced changes in the aquatic communities within the Whiskeytown National Recreational Area. Benthic sediment results for metals of biological concern were compared with consensus-based probable effect concentrations from previously published sediment-quality guidelines. Results from 2020 sampling indicated exceedances of these guidelines at one site for cadmium, chromium, copper, and zinc; there were exceedances of the guidelines at three sites for nickel. Concentrations of metals of biological concern in fish and invertebrate tissue samples generally varied among sites and years, with no pattern with specific reference to the Carr Fire. Average zinc and lead concentrations in composite invertebrate samples were slightly higher in 2020 than in previous years, and arsenic levels were lower in 2020 for invertebrate and fish tissues. Post-Carr Fire stream-habitat and sediment-size characterization values did not change substantially when compared to pre-Carr Fire values, or had high variation among all sites and years. Fish and amphibian inventories demonstrated that fewer total fish and amphibians were collected post-Carr Fire, but higher numbers of native Sacramento Sucker ( Catostomus occidentalis ) and Sacramento Pikeminnow ( Ptychocheilus grandis ) were collected than in previous years. The combined histories of mining and frequent wildfires in the area pose an increased risk for metal contamination throughout the aquatic system. Continued monitoring for multilevel trophic effects of contaminants can provide information about the overall health of the Whiskeytown National Recreation Area and surrounding region.
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On February 13, 2001, a magnitude 6.5 earthquake occurred about 40 km eastsoutheast of the capital city of San Salvador in central El Salvador and triggered thousands of landslides in the area east of Lago de Ilopango. The landslides are concentrated in a 2,500-km2 area and are particularly abundant in areas underlain by thick deposits of poorly consolidated, late Pleistocene and Holocene Tierra Blanca rhyolitic tephras that were erupted from Ilopango caldera. Drainages in the tephra deposits are deeply incised, and steep valley walls failed during the strong shaking. Many drainages are clogged with landslide debris that locally buries the adjacent valley floor. The fine grain-size of the tephra facilitates its easy mobilization by rainfall runoff. The potential for remobilizing the landslide debris as debris flows and in floods is significant as this sediment is transported through the drainage systems during the upcoming rainy season. In addition to thousands of shallow failures, two very large landslides occurred that blocked the Rio El Desague and the Rio Jiboa. The Rio El Desague landslide has an estimated volume of 1.5 million m3, and the Rio Jiboa landslide has an estimated volume of 12 million m3. Field studies indicate that catastrophic draining of the Rio El Desague landslide-dammed lake would pose a minimal flooding hazard, whereas catastrophic draining of the Rio Jiboa lake would pose a serious hazard and warrants immediate action. Construction of a spillway across part of the dam could moderate the impact of catastrophic lake draining and the associated flood. Two major slope failures on the northern side of Volcan San Vicente occurred in the upper reaches of Quebrada Del Muerto and the Quebrada El Blanco. The landslide debris in the Quebrada Del Muerto consists dominantly of blocks of well-lithified andesite, whereas the debris in the Quebrada El Blanco consists of poorly consolidated pyroclastic sediment. The large blocks of lithified rock in Quebrada Del Muerto are unlikely to be remobilized during the rainy season; whereas, the sandy and silty landslide debris in the channel of Quebrada El Blanco is susceptible to remobilization as debris flows that could extend into populated areas on the lower slopes of the volcano. Around the northern and eastern shore of Lago de Ilopango, earthquake-induced liquefaction and lateral-spreading landslides caused local damage to homes and other structures; this damage was most prevalent in the village of San Agustin. San Agustin is also potentially threatened by floods because it is located on the alluvial fan of the Quebrada El Chaguite drainage basin, which contains hundreds of landslides that have choked numerous small channels with volcanic tephra. As the easily eroded tephra is transported down the drainage system and deposited on the alluvial fan, it could clog the currently active channel with sediment, divert the stream into a new channel, and possibly direct flow through San Agustin, causing more damage and destruction
Material inventories for prospective sources of material for use in building roads and associated structures were prepared by Arizona for several counties including Maricopa County. The inventories provide information about pit locations, materials classification and type, and measures of some characteristics used to determine suitability for aggregate. The digital data given in this release was published by the (ADOT, 1977) in cooperation with the Federal Highway Administration. This is one of a series of material inventories prepared for Arizona’s counties by ADOT since compilation began in 1959. The data set developed here faithfully follows the data given in ADOT (1977) with minimal changes. Names of variables used in the digital data set are shown in Table 2.