USGS Science⌕ Search

Geology topics

D.A. Stedfast

Publications and source records attributed to D.A. Stedfast.

7 recordsLinked to original sources
USGS1996

Vulnerability of public drinking water supplies in New Jersey to pesticides

Beginning in 1993, Safe Drinking Water Act (SDWA) regulations required the 626 large community water systems in New Jersey to monitor their 2,600 wells and 45 surface-water intakes quarterly for 23 pesticides. Monitoring costs would increase consumers’ water bills by $6.4 million each year. The New Jersey Department of Environmental Protection (NJDEP) can waive monitoring requirements for wells or intakes that are not vulnerable to pesticide contamination. The U.S. Geological Survey (USGS), in cooperation with NJDEP, determined the vulnerability of wells and surface-water intakes to pesticide contamination on the basis of hydrogeology and pesticide use. The NJDEP estimated that because many wells and intakes are not vulnerable to contamination by pesticides, monitoring waivers will save taxpayers at least $5.1 million annually for a one-time study cost of $1 million.

New Jersey↗
USGS1986

Evaluation of six methods for estimating magnitude and frequency of peak discharges on urban streams in New York

Six methods of estimating peak discharges of urban streams were compared and evaluated for applicability to urban streams in New York. Discharge and frequency values developed from a series of synthesized annual flood records were compared with values obtained from the six methods. The synthesized flood records were computed from rainfall-runoff models of 11 urban basins in three counties across the State. Four of these basins had a sufficient period of record to enable rainfall-runoff modeling of two different 5-year periods so that increases in peak flow due to increased urbanization could also be used for comparison of the six methods. A graphical analysis and three types of mathematical analyses were made to evaluate the closeness of fit and bias of the methods. All methods showed a tendency to overestimate synthetic urban flood-magnitude values, but the two adjust rural flood-frequency estimates on a nationwide basis showed smallest standard errors of estimate and bias. The standard errors for these two methods ranged from 44 to 57 percent over the six recurrence intervals (2, 5, 10, 25, 50, and 100 year), and the bias ranged from +28 to +53 percent. The bias , however, is probably due to errors inherent in using synthetic records and in applying the New York rural flood-frequency equations to urban basins with small drainage areas. (USGS)

Water-Resources Investigations Report↗
USGS1986

Reaeration coefficients of six streams in New York; a comparison of results obtained by a hydrocarbon-gas tracer method with those obtained by radioactive tracers and predictive equations

Stream-reaeration measurements were made in selected reaches on six streams in New York State from 1978 to 1981 with hydrocarbon-gas and dye tracers. The sites were Canadaigua Outlet near Canadaigua, Oswego River at Fulton, Hudson River at Fort Miller, Cayadutta Creek near Johnstown, Chenango River near Morrisville, and Payne Brook near Hamilton. The reaches represent a wide range of discharge, water-surface slope, velocity, and streambed composition. Flows ranged from less than 2 cu ft/sq on the Chenango River to 4,100 cu ft/sq on the Hudson River, and water-surface slope within the reaches ranged from less than 1 foot/mile on the Hudson and Oswego Rivers to more than 50 ft/mi on Cayadutta Creek. The corresponding stream-reaeration coefficients ranged from 0.77 units/day for one reach on Canadaigua Outlet to 52 units/day on Cayadutta Creek. The reaeration coefficients for Canadaigua Outlet compared well with those obtained on the same reach 10 years earlier by radioactive tracers. Comparison of measured reaeration coefficients with those calculated from 10 predictive equations based on stream-channel characteristics yielded mean errors that range from 51% to 103%. No single equation gave reliable accuracy for all stream reaches. (USGS)

Water-Resources Investigations Report↗
USGS1983

An assessment of steady-state propane-gas tracer method for reaeration coefficients — Cowaselon Creek, New York

Three tests were conducted in a straight 5.2-km reach of the Cowaselon Creek, Canastota, New York, in order to assess feasibility of the steady-state propane-gas tracer method as a means of estimating in situ reaeration coefficients. It is concluded that the steady-state method, which combines as instantaneous injection of dye tracer with a long-duration injection of propane tracer, is an operationally feasible field technique and provides a very reliable means of determining the propane desorption coefficient in steady-channel flow. The effect of wind shear on propane desorption coefficients was not detected in any tests, apparently due to the sheltering effect of high banks. The reaeration coefficient is estimated by applying a conversion factor determined from laboratory experiments to the gas desorption coefficient.

New York↗
USGS1980

Cross sections of the Hudson River estuary from Troy to New York City, New York

Data on channel geometry of the Hudson River estuary at 125 cross sections between the Federal Dam at Troy and the norhtern limits of New York City (133 miles) are presented for use in hydraulic modeling, tidal studies, traveltime and water-quality studies, and other uses requiring knowledge of Hudson River channel properties. The data were obtained from field surveys of the estuary conducted by boat with a fathometer in 1966-69. Water-surface elevations were not recorded during the fathometer runs but were calculated in 1979 from information on tide variations in the estuary and from stage data collected at Albany and New York City. Topographic maps and field reconaissance were used to extend the ends of the cross sections beyond 100-year flood stage. Channel-configuration data are presented as perspective plots and in a table; also included are strip maps showing the location of the cross sections. (USGS)

Water-Resources Investigations Report↗
USGS1979

Low-flow characteristics of streams in the Pecatonica-Sugar River basin, Wisconsin

The purpose of this report is to describe low-flow characteristics of streams in the Pecatonica-Sugar River basin, Wisconsin, where streamflow data have been collected, and to present equations for estimating low-flow characteristics at ungaged sites. Low-flow characteristics were estimated for 11 gaging stations, 25 low-flow partial-record stations, and 207 miscellaneous sites in the basin. Estimates of flow duration were made at the 11 gaging stations. Also, low-flow discharge measurements are listed for 16 miscellaneous sites where insufficient data were available to estimate low-flow characteristics. Four equations are provided to estimate low-flow characteristics at ungaged sites and at sites where one base-flow discharge measurement is available. The equations were determined from multiple-regression analyses that related low-flow characteristics at gaging stations and partial-record stations to basin characteristics. Drainage area and base-flow index were the most significant parameters for these analyses. The standard error of estimate of the 7-day, 10-year low flow was provided. The average SE-j f iQ in the basin ranged from 10 to 64 percent and was dependent on the amount of low-flow data available.

Wisconsin↗