Publications

This study used a 20-year dataset (1995–2014) to identify factors affecting cyanobacterial community composition (CCC) and abundance in a eutrophic lake. We hypothesized that differences in thermal structure, nutrients, and meteorology drive interannual variability in CCC and abundance. Cluster analysis differentiated dominant cyanobacteria into rare, low abundance, or sporadically...

Dividing the Waters offers this groundwater science bench book that cannot be matched by any other scientific or judicial publication. Adjudicating Groundwater combines the expertise and experience of academic scientists (UC Davis/Stanford), federal scientists (U.S. Geological Survey), and judicial officers to create a resource that can fulfill the needs of judges tackling the most...

Nutrient inputs from commercial agricultural fertilizer, particularly nitrogen and phosphorus, are important factors contributing to the degradation of surface-water quality and the alteration of aquatic ecosystems. Despite this importance, information about the application of fertilizer to agricultural land is not available in a consistent manner across the United States at a scale...

Cache Creek drains part of northern California’s Coast Ranges and is an important source of mercury (Hg) to the Sacramento–San Joaquin Delta. Cache Creek is contaminated with Hg from several sources, including historical Hg and gold mines, native Hg in the soils, and active mineral springs. In laboratory experiments in a study conducted by the U.S. Geological Survey, in cooperation with...

The effectiveness of Integrated Water Resource Management (IWRM) modeling hinges on the quality of practices employed through the process, starting from early problem definition all the way through to using the model in a way that serves its intended purpose. The adoption and implementation of effective modeling practices need to be guided by a practical understanding of the variety of...

The precise quantification of mercury (Hg) stable isotope compositions in low concentration or dilute samples poses analytical challenges due to Hg mass limitations. Common Hg pre-concentration procedures require extended processing times, making rapid Hg stable isotope measurements challenging. Here we present a modified pre-concentration method that combines commonly used Hg reduction...

Lake Pepin is the largest naturally formed lake on the Mississippi River and has complex management needs to satisfy economic, environmental, and cultural demands. Lake Pepin is filling in with sediment at a rapid rate compared to conditions before settlement by European immigrants and intense agricultural cultivation. Accordingly, the Minnesota Pollution Control Agency has developed...

In general, fish residing in rivers differ from fish residing in lakes in their mercury (Hg) isotope ratios. Specifically, fish residing in lakes typically show enriched values for the isotope ratios of δ202Hg (mass-dependent fractionation of isotope 202Hg) and Δ199Hg (mass-independent fractionation of isotope 199Hg) compared with fish residing in rivers, because photochemical effects...

Ice provides a range of ecosystem services—including fish harvest, cultural traditions, transportation, recreation and regulation of the hydrological cycle—to more than half of the world’s 117 million lakes. One of the earliest observed impacts of climatic warming has been the loss of freshwater ice, with corresponding climatic and ecological consequences. However, while trends in ice...

Sediment oxygen demand (SOD) plays a fundamental role in biological and chemical processes within the benthic layer of a water body. Land use, including agricultural land use, can affect SOD. However, a wide variety of approaches have been used for in situ SOD chamber construction and data collection, and modelers frequently use SOD values from the literature, without consideration of...

A groundwater flow model for western Chippewa County, Wisconsin, was developed by the Wisconsin Geological and Natural History Survey (WGNHS) and the U.S. Geological Survey (USGS) using the computer program MODFLOW. The model is the result of a five-year groundwater study commissioned by Chippewa County in 2012 to evaluate the effects of industrial sand mining and irrigated agriculture...

In this report, SPAtially Referenced Regression On Watershed attributes (SPARROW) models developed to describe long-term (2000–14) mean-annual streamflow, total nitrogen (TN), total phosphorus (TP), and suspended-sediment (SS) transport in streams of the Midwestern part of the United States (the Mississippi River, Great Lakes, and Red River of the North Basins) are described. The...