Publications

The trunk channels of each system are 2 to 4 km wide and are incised 30 to 50 m into underlying strata; they have irregular longitudinal profiles and very low gradients within the Chesapeake Bay area. The youngest paleochannel is clearly of late Wisconsinan age, about 18 ka, and the intermediate one appears to be late Illinoian in age, or about 150 ka. The age of the oldest is in the...

Simultaneous on‐site and in situ studies of survival of prolarval and yearling striped bass Morone saxatilis were conducted in the Potomac River during the 1988 spawning season. Various water quality and contaminant conditions were monitored during these experiments. In situ experiments on yearlings and monitoring of water quality and contaminants were also conducted in the Susquehanna...

Several recent articles have called attention to the problem of retransformation bias, which can arise when log linear regression models are used to estimate sediment or other constituent loads. In some cases the bias can lead to underestimation of constituent loads by as much as 50%, and several procedures have been suggested for reducing or eliminating it. However, some of the...

Eastern box turtles (Terrapene c. carolina) in a Maryland bottomland forest were studied over a period of years (1944-1981). Home ranges of 51 males averaged 146 + SD 48 m long and 105 + SD 38 m wide; ranges of 52 females averaged 144 + SD 52 m long and 100 + SD 38 m wide. An approximation of average home range size, based on an ellipse, is 1.20 ha for males and 1.13 ha for females...

All water that reaches watershed systems comes directly or indirectly from precipitation. Normally, this water contains very small amounts of dissolved solids and is only slightly acidic. As a result of chemical reactions in watersheds, however, stream water generated from precipitation normally is less acidic and contains larger concentrations of dissolved solids than does the...

The Chesapeake Bay receives nearly 1 000 000 tonnes of sediment annually from its major tributary, the Susquehanna River. The pattern of deposition of this sediment affects the lifetime of the estuarine resource and the fate of any sediment-borne contaminants. Previous estimates of the extent to which Susquehanna River sediment is transported down the Chesapeake have differed...

Wells in the Gettysburg National Military Park, Eisenhower National Historic Site, and Gettysburg Borough supply drinking water to the park staff and, annually, more than 1 million visitors. These water resources are vulnerable to contamination by pollutants from activities in and outside park boundaries. This report describes the hydrogeology and ground-water quality of a 12-square-...

On an annual basis, river-supplied nitrate is the predominant form of nitrogen supplied to the tidal Potomac River from external sources. Much of the nitrate is associated with high flows that have rapid transit times through the tidal river. The Blue Plains Sewage-Treatment Plant (STP) at Washington, D.C., is the greatest source of all nitrogen species during low-flow periods. Prior to...

During periods of sediment resuspension, desorption of ammonium from sediment solids can be the major pathway for enriching the water column with the ammonium that is produced by bacterial degradation of organic matter in the bottom material. This hyopthesis is based on a three-year study of diffusive flux in the transition zone of the Potomac River at a site 35 m from the Virginia shore...

The U.S. Geological Survey is conducting a water quality study as part of the nationally implemented Rural Clean Water Program in the headwaters of the Conestoga River, Pennsylvania. The study, which began in 1982, was designed to determine the effect of agricultural best management practices on surface--and groundwater quality. The study was concentrated in four areas within the...

The characteristics and distributions of near-surface bottom sediments and of nutrients in the sediments provide information on modern sediment and nutrient sources, sedimentation environments, and geochemical reactions in the tidal Potomac system, Maryland and Virginia. This information is fundamental to an improved understanding of sedimentation and eutrophication problems in the tidal...

The Potomac River at Chain Bridge is the major riverine source of dissolved silica (DSi) to the tidal Potomac River and Estuary. DSi concentrations at Chain Bridge are positively correlated with river discharge; river discharge is an important factor controlling rates of supply, dilution, and residence time. When river flow is high, the longitudinal DSi distribution is conservative. When...