All Publications

Multiple generations of spring-fed streams traversed ∼800 km2 of the Las Vegas Valley in southern Nevada between ca. 10.9 ka and 8.5 ka, depositing an extensive tufa network. The scale of this network and diversity of tufa morphologies is novel in North America and offers an opportunity to obtain quantitative paleoclimate data for the region during the early Holocene. We determined...

Louisiana black bears (Ursus americanus luteolus) occur in semi-isolated fragments of bottomland hardwood forest in the lower Mississippi Alluvial Valley and were listed as threatened under the United States Endangered Species Act in 1992. A population viability analysis based on radio-telemetry and capture-mark-recapture (CMR) data collected from 2002 to 2012 revealed that the...

Household well water can be degraded by contaminants from the land's surface, but private well owners lack means to protect the source water from neighboring disturbances. Rural residents of southwestern Wisconsin, USA, rely on private well water, and the combination of land use and fractured carbonate bedrock makes groundwater vulnerable to contamination. To identify the extent, sources...

Traditional flood frequency methods assume that the statistical properties of peak streamflow do not change with time and may not be appropriate for many areas in the north-central United States. This study examines a nonstationary flood frequency analysis method that uses ordinary least squares linear regression to estimate flood magnitudes at U.S. Geological Survey streamgages that...

The rhyolitic Kaharoa 1315 CE eruption was a complex, long-lived event from Tarawera volcano, New Zealand. Explosive phases were followed by around 5 years of lava dome extrusion and collapse which produced block-and-ash flows (BAF). Lava domes generate crystalline silica in the form of cristobalite, and rhyolitic magmas often contain quartz phenocrysts. Fine-grained ash containing...

The U. S. Geological Survey-Great Lakes Science Center has monitored annual changes in the offshore (depth > 9m) prey fish community of Lake Huron since 1973. Monitoring of prey fish populations in Lake Huron is based on a bottom trawl survey that targets demersal species (i.e., those predominantly or intermittently associated with the lake bottom) and an acoustic-midwater trawl survey...

Coastal Louisiana is known for saltwater intrusion that threatens wetlands, aquifers, and rivers. However, the extent of saltwater intrusion is not well understood. This study develops an innovative framework with airborne electromagnetic (AEM) data to map chloride concentration distributions for wetlands in the Mississippi River deltaic plain and Chenier plain as well as for the...

Ongoing, prolonged, and severe drought and water overuse during the first two decades of the 21st century have reduced water supplies of the Colorado River Basin, with effects cascading to ecosystems and human communities throughout the basin. In June and July 2021, the U.S. Geological Survey (USGS) Colorado River Basin Actionable and Strategic Integrated Science and Technology...

Federally managed public lands and waters attract millions of visitors each year, generating significant economic benefits for surrounding communities. Accurate visitation data are crucial for guiding policy decisions and managing resources effectively. This report explores the methods employed by agencies to collect and use data on recreational visitation to Federal lands and waters...

No abstract available.

Geological studies in the Cretaceous Western Interior Seaway (KWIS) in North America reveal highly variable sedimentological conditions on its western shore caused by rapidly changing sea level and detrital input during the seaway’s closure. Here we examine a 601-foot (183 meters) continuous core through the lower part of the Maastrichtian Lewis Shale in the eastern Washakie Basin...

No abstract available.