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At least 1,531 records · Page 85Linked to original sources
USGS2016

Estimating flood magnitude and frequency at gaged and ungaged sites on streams in Alaska and conterminous basins in Canada, based on data through water year 2012

Estimates of the magnitude and frequency of floods are needed across Alaska for engineering design of transportation and water-conveyance structures, flood-insurance studies, flood-plain management, and other water-resource purposes. This report updates methods for estimating flood magnitude and frequency in Alaska and conterminous basins in Canada. Annual peak-flow data through water year 2012 were compiled from 387 streamgages on unregulated streams with at least 10 years of record. Flood-frequency estimates were computed for each streamgage using the Expected Moments Algorithm to fit a Pearson Type III distribution to the logarithms of annual peak flows. A multiple Grubbs-Beck test was used to identify potentially influential low floods in the time series of peak flows for censoring in the flood frequency analysis. For two new regional skew areas, flood-frequency estimates using station skew were computed for stations with at least 25 years of record for use in a Bayesian least-squares regression analysis to determine a regional skew value. The consideration of basin characteristics as explanatory variables for regional skew resulted in improvements in precision too small to warrant the additional model complexity, and a constant model was adopted. Regional Skew Area 1 in eastern-central Alaska had a regional skew of 0.54 and an average variance of prediction of 0.45, corresponding to an effective record length of 22 years. Regional Skew Area 2, encompassing coastal areas bordering the Gulf of Alaska, had a regional skew of 0.18 and an average variance of prediction of 0.12, corresponding to an effective record length of 59 years. Station flood-frequency estimates for study sites in regional skew areas were then recomputed using a weighted skew incorporating the station skew and regional skew. In a new regional skew exclusion area outside the regional skew areas, the density of long-record streamgages was too sparse for regional analysis and station skew was used for all estimates. Final station flood frequency estimates for all study streamgages are presented for the 50-, 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent annual exceedance probabilities. Regional multiple-regression analysis was used to produce equations for estimating flood frequency statistics from explanatory basin characteristics. Basin characteristics, including physical and climatic variables, were updated for all study streamgages using a geographical information system and geospatial source data. Screening for similar-sized nested basins eliminated hydrologically redundant sites, and screening for eligibility for analysis of explanatory variables eliminated regulated peaks, outburst peaks, and sites with indeterminate basin characteristics. An ordinary least‑squares regression used flood-frequency statistics and basin characteristics for 341 streamgages (284 in Alaska and 57 in Canada) to determine the most suitable combination of basin characteristics for a flood-frequency regression model and to explore regional grouping of streamgages for explaining variability in flood-frequency statistics across the study area. The most suitable model for explaining flood frequency used drainage area and mean annual precipitation as explanatory variables for the entire study area as a region. Final regression equations for estimating the 50-, 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent annual exceedance probability discharge in Alaska and conterminous basins in Canada were developed using a generalized least-squares regression. The average standard error of prediction for the regression equations for the various annual exceedance probabilities ranged from 69 to 82 percent, and the pseudo-coefficient of determination (pseudo-R 2 ) ranged from 85 to 91 percent. The regional regression equations from this study were incorporated into the U.S. Geological Survey StreamStats program for a limited area of the State—the Cook Inlet Basin. StreamStats is a national web-based geographic information system application that facilitates retrieval of streamflow statistics and associated information. StreamStats retrieves published data for gaged sites and, for user-selected ungaged sites, delineates drainage areas from topographic and hydrographic data, computes basin characteristics, and computes flood frequency estimates using the regional regression equations.

Alaska↗
USGS2019

Survival and recruitment dynamics of Black-legged Kittiwakes Rissa tridactyla at an Alaskan colony

The majority of seabirds breed colonially and exhibit considerable site fidelity over the course of their long lifespans. Initial colony selection can therefore have substantial fitness consequences; however, factors contributing to recruitment into colonies and subsequent fidelity remain unclear. We used multi-state capture-recapture models to test several hypotheses related to apparent fledgling survival, the probability of recruitment to natal colonies, and apparent post-recruitment survival in Black-legged Kittiwakes with data from individuals banded as chicks and subsequently resighted at a colony in south-central Alaska over a twenty-year period. Competitive models suggested that apparent fledgling survival declined throughout our study; this decline was likely driven by intrinsic, cohort-specific processes and was not explainable by post-fledging wind and climate conditions. Independent resightings at other colonies suggest the apparent decline may have been at least partially influenced by permanent emigration (natal dispersal) that occurred more frequently when the colony size was large. Recruitment was primarily age-dependent, with no detectable effect of early life experience or annual changes in colony size, colony productivity, climate, or average weather conditions. We estimated an average recruitment age of seven years, which is older than typically reported for Atlantic kittiwake populations, and supports a more conservative life history strategy for kittiwakes in the Pacific. Variation in apparent survival of recruits was cohort-specific and did not correlate with age or annual changes in the factors listed above. Instead, apparent survival of recruits was best explained by colony size during a cohort’s second year, suggesting a degree of negative density dependence in post-recruitment survival or fidelity. This information could prove useful to managers deciding how to allocate resources among small, growing colonies and large, well-established colonies.

Alaska↗
USGS2013

Annual exceedance probabilities of the peak discharges of 2011 at streamgages in Vermont and selected streamgages in New Hampshire, western Massachusetts, and northeastern New York

The U.S. Geological Survey, in cooperation with the Federal Emergency Management Agency, determined annual exceedance probabilities for peak discharges occurring during the 2011 water year (October 1 to September 30) at streamgages in Vermont and selected streamgages in New Hampshire, western Massachusetts, and northeastern New York. This report presents the 2011 water year peak discharges at 145 streamgages in the study area and provides the results of the analyses of the 50-, 20-, 10-, 4-, 2-, 1-, and 0.2-percent annual exceedance probability discharges at 135 of the 145 streamgages. The annual exceedance probabilities for the 2011 water year peak discharges also are presented. Snowmelt and near record rainfall led to flooding across northern Vermont on April 27 and 28, 2011. At three streamgages with more than 10 years of record, the April rain event resulted in the peak discharge of record. At seven streamgages, the peak discharge resulting from this event had an annual exceedance probability less than or equal to 1 percent. In early May 2011, new peak stage records were set at two Lake Champlain gages with more than 100 years of record. At the Lake Champlain at Burlington, Vermont, gage, the water surface reached 102.79 feet (ft) (North American Vertical Datum of 1988 (NAVD 88)) on May 6, 2011, and at the Richelieu River (Lake Champlain) at Rouses Point, New York, gage, the water surface reached 102.75 ft NAVD 88. Record-breaking rainfall in late May produced additional flooding across northern Vermont on May 26 and 27, 2011. Four streamgages in northwestern Vermont recorded peak-of-record discharges as a result of this flooding. At three streamgages, the peak discharges from this event had an annual exceedance probability less than or equal to 1 percent. From August 28 to 29, 2011, Tropical Storm Irene delivered rainfall totals ranging from about 3 to more than 10 inches, which resulted in extensive flooding and new period-of-record peak discharges at 37 streamgages in the study area. The peak discharges as a result of Tropical Storm Irene had an annual exceedance probability of less than or equal to 1 percent at 36 streamgages. At 11 of these 36 streamgages, the annual exceedance probability of the peak discharges was less than or equal to 0.2 percent.

Massachusetts;New Hampshire;New York;Vermont↗
USGS2011

Improved mapping of National Atmospheric Deposition Program wet-deposition in complex terrain using PRISM-gridded data sets

High-elevation regions in the United States lack detailed atmospheric wet-deposition data. The National Atmospheric Deposition Program/National Trends Network (NADP/NTN) measures and reports precipitation amounts and chemical constituent concentration and deposition data for the United States on annual isopleth maps using inverse distance weighted (IDW) interpolation methods. This interpolation for unsampled areas does not account for topographic influences. Therefore, NADP/NTN isopleth maps lack detail and potentially underestimate wet deposition in high-elevation regions. The NADP/NTN wet-deposition maps may be improved using precipitation grids generated by other networks. The Parameter-elevation Regressions on Independent Slopes Model (PRISM) produces digital grids of precipitation estimates from many precipitation-monitoring networks and incorporates influences of topographical and geographical features. Because NADP/NTN ion concentrations do not vary with elevation as much as precipitation depths, PRISM is used with unadjusted NADP/NTN data in this paper to calculate ion wet deposition in complex terrain to yield more accurate and detailed isopleth deposition maps in complex terrain. PRISM precipitation estimates generally exceed NADP/NTN precipitation estimates for coastal and mountainous regions in the western United States. NADP/NTN precipitation estimates generally exceed PRISM precipitation estimates for leeward mountainous regions in Washington, Oregon, and Nevada, where abrupt changes in precipitation depths induced by topography are not depicted by IDW interpolation. PRISM-based deposition estimates for nitrate can exceed NADP/NTN estimates by more than 100% for mountainous regions in the western United States.

Environmental Monitoring and Assessment↗
USGS1996

Deicing chemicals as source of constituents of highway runoff

The dissolved major and trace constituents of deicing chemicals as a source of constituents in highway runoff must be quantified for interpretive studies of highway runoff and its effects on surface water and groundwater. Dissolved constituents of the deicing chemicals—sodium chloride, calcium chloride, and premix (a mixture of sodium and calcium chloride)—were determined by analysis of salt solutions created in the laboratory and are presented as mass ratios to chloride. Deicing chemical samples studied are about 98 and 97 percent pure sodium chloride and calcium chloride, respectively; however, each has a distinct major and trace ion constituent signature. The greatest impurity in sodium chloride road salt samples was sulfate, followed by calcium, potassium, bromide, vanadium, magnesium, fluoride, and other constituents with a ratio to chloride of less than 0.0001 by mass. The greatest impurity in the calcium chloride road salt samples was sodium, followed by potassium, sulfate, bromide, silica, fluoride, strontium, magnesium, and other constituents with a ratio to chloride of less than 0.0001 by mass. Major constituents of deicing chemicals in highway runoff may account for a substantial source of annual chemical loads. Comparison of estimated annual loads and first flush concentrations of deicing chemical constituents in highway runoff with those reported in the literature indicate that although deicing chemicals are not a primary source of trace constituents, they are not a trivial source, either. Therefore, deicing chemicals should be considered as a source of many major and trace constituents in highway and urban runoff.

Transportation Research Record↗
USGS1985

Annual yield and selected hydrologic data for the Arkansas River Basin Compact, Arkansas-Oklahoma, 1984 water year

The computer annual yield and deficiency of the subbasins as defined in the Arkansas River Compact, Arkansas-Oklahoma, are given in tables. Actual runoff from the subbasins and depletion caused by major reservoirs in the compact area are also given in tabular form. Monthly, maximum, minimum, and mean discharges are shown for the 14 streamflow stations used in computing annual yield.

Arkansas, Oklahoma↗
USGS1989

Statistical summary of streamflow data for Indiana

Statistical analyses of daily mean discharge values collected at 229 Indiana streamflow-gaging stations are presented. For each station, data collected from the beginning of period of record through the 1985 water year were analyzed. Summaries include flow-duration, high-flow, and low-flow tables, and monthly and annual mean discharge. (USGS)

Indiana↗
USGS2008

Precipitation, Ground-water Hydrology, and Recharge Along the Eastern Slopes of the Sandia Mountains, Bernalillo County, New Mexico

The spatial and temporal distribution of recharge to carbonate and clastic aquifers along the eastern slopes of the Sandia Mountains was investigated by using precipitation, water-level, dissolved chloride, and specific-conductance data. The U.S. Geological Survey (USGS), in cooperation with the Bernalillo County Public Works Division, conducted a study to assess ground-water conditions and provide technical data that could be used as a basis for management and future planning of eastern Bernalillo County water resources. The intent of the investigation was to improve the current understanding of subsurface mechanisms controlling recharge dynamics in a geologically complex aquifer system. In the Sandia Mountains, precipitation events are generally limited to snowfalls in winter months and monsoon rainfall in late summer. Monthly meteorological data from weather stations in the study area indicate that monsoon rainfall during July and August constitutes close to one-third of annual precipitation totals. Following precipitation and snowmelt events, daily ground-water level data show low-amplitude, long-duration peaks in hydrographs of wells north and west of the Tijeras Fault. Hydrographs of monthly and biannual water-level data from across the study area show seasonal variation and water-level fluctuations in excess of 30 ft during a period of below-average precipitation. Water level observations in 67 percent of wells showing drought-induced water-level declines rebounded to at or near predrought conditions within 6 months of return to normal climate conditions. Cross-correlation of annual hydrologic data shows aquifer response to periods of monsoon recharge to persist from 1 to 6 months following events. The lag time between precipitation input and response of water levels or solute concentrations was largest near the Tijeras and Gutierrez Faults. These results indicate regional faults hydrologically isolate the Tijeras Graben from groundwater recharge originating at high elevations along the eastern slopes of the Sandia Mountains. Recharge rates calculated by using the chloride-mass-balance method for five springs located at the base of the Sandia Mountains ranged from 1 to 23 percent of annual precipitation.

Scientific Investigations Report↗
USGS2018

Annual and approximately quarterly series peak streamflow derived from interpretations of indirect measurements for a crest-stage gage network in Texas through water year 2015

In 2006, the U.S. Geological Survey (USGS), in cooperation with the Texas Department of Transportation, began collecting annual and approximately quarterly series peak-streamflow data at streamflow-gaging stations in smallto medium-sized watersheds in central and western Texas as part of a crest-stage gage (CSG) network, along with selected flood-hydrograph data at a subset of these stations. CSGs record the peak stage during storm events, which is the maximum gage height (elevation of water surface above a local vertical datum), at each CSG station. Established and widely used indirect methods of peak streamflow estimation and interpretation, such as culvert-flow, slope-area, and flow-over-road methods, are used in conjunction with peak gage height data to create the database of peak streamflow described herein. The CSG network is focused on hydrology of small- to medium-sized watersheds in central and western Texas because additional streamflow data for this semiarid to arid study area will eventually provide for more statistical information and presumably reduced uncertainty in regional regression equations or other regionalized statistical methods for peak-streamflow frequency estimation at ungaged locations. The database of annual and approximately quarterly peak streamflow is published through USGS ScienceBase and described in this report.

Texas↗
USGS2026

Peak-, mean-, and low-streamflow regional-regression equations for natural streamflow in central and western Colorado, 2019

The U.S. Geological Survey (USGS), in cooperation with the Colorado Department of Transportation, developed peak-, mean-, and low-streamflow regional-regression equations for estimating various statistics for natural streamflow in hydrologic regions of central and western Colorado. The peak-streamflow regression equations were developed using data from 418 streamgages, consisting of 15,202 years of record and a mean of approximately 36 years of record per streamgage. The mean- and low-streamflow regional-regression equations were developed using data from 323 streamgages where daily streamflow data were collected year-round. The annual exceedance-probability discharges for each streamgage were computed using the USGS software program PeakFQ. Mean monthly and 7-day minimum and maximum streamflows were computed using the USGS software program SWToolbox. Streamflow-duration values were computed using an R script. The regional-regression equations were determined using data for the period of record for a given streamgage through water year 2019. Geographic information systems datasets were used to develop 55 basin and 42 climatic characteristics, which were evaluated as candidate explanatory variables in the regression analysis. For the peak-streamflow regional-regression equations, the study area was divided into four hydrologic regions based on mean basin elevation, including the Plateau (less than 8,014 feet), Mid-Elevation (8,015 feet to 9,492 feet), Sub-Alpine (9,493 feet to 10,490 feet), and Alpine (greater than 10,490 feet) regions. For the peak-streamflow equations, the selection of basin and climatic characteristics was based on the 1-percent annual exceedance-probability discharge for each hydrologic region. For the mean streamflow, streamflow-duration values, and 7-day minimum and maximum streamflows, the study area was divided into four hydrologic regions based on river basin, including the (1) Colorado-East Slope Headwaters, (2) Green River, (3) Rio Grande, and (4) San Juan-Dolores. For mean streamflows, basin and climatic characteristics were evaluated separately for the annual period and each month for each hydrologic region. Regional regression equations published in this report are available for use in the USGS web-based program StreamStats.

Colorado↗
USGS2000

Hydrology, water quality, and phosphorus loading of Little St. Germain Lake, Vilas County, Wisconsin

Little St. Germain Lake, which is in Vilas County. Wisconsin, just northeast of St. Germain (fig. 1), is one of 21 impoundments operated by Wisconsin Valley Improvement Company (WVIC) to provide storage for power and recreational use. The level of the lake, which was originally dammed in 1882, has been maintained by the WVIC at about 5 feet above its natural level since 1929, and it is annually drawn down about 1.5 feet from December through March. In the interest of protecting and improving the water quality of the lake, the Little St. Germain Lake Improvement Association was established in 1959. Later, the I .ittle St. Germain Lake District was formed. The Wisconsin Department of Natural Resources (WDNR), in collaboration with the Lake District, did a study during 1983-85 to document the water quality of the lake and examine management alternatives (Wisconsin Department of Natural Resources, 1985). Results of the study indicated that, because of relatively high phosphorus loading to the lake, most of the lake was eutrophic (relatively productive), with the possible exception of the West Bay. The results also indicated monitoring of the lake should continue, and that actions should be taken to decrease nutrient loading to the lake by controlling erosion, fertilizer runoff, and leakage from septic systems. The lake was monitored in detail again during 1991-94 by the U.S. Geological Survey (USGS) as part of a cooperative study with the Lake District. This study demonstrated water-quality variation among the basins of Little St. Germain Lake and extensive areas of winter anoxia (absence of oxygen). Further in-depth studies were then conducted during 1994-2000 to define the extent of winter anoxia, refine the hydrologic and phosphorus budgets of the lake, quantify the effects of annual drawdowns, and provide information needed to develop a comprehensive lake-management plan. This report presents the results of the studies since 1991.

Wisconsin↗
USGS2003

Suspended sediment and bed load in three tributaries to Lake Emory in the upper Little Tennessee River basin, North Carolina, 2000-02

A study was conducted in the upper Little Tennessee River basin to characterize suspended-sediment and bed-load sediment transport into Lake Emory from the main stem and two major tributaries--Cartoogechaye Creek and the Cullasaja River. Suspended-sediment concentrations in the discharge from Lake Emory also were measured. Weekly samples for suspended-sediment concentration were collected between November 2000 and November 2001, and periodic samples were collected during targeted high-flow events. Suspended-sediment samples were collected during stormwater runoff conditions for analysis of particle-size distribution. Three bed-load samples were collected at each stream site. The greatest annual load (5,700 metric tons) and yield (18 metric tons per square kilometer) of suspended sediment during the study period were in the Little Tennessee River near Riverside, North Carolina. Much smaller annual yields were calculated for Lake Emory, the Cullasaja River, and Cartoogechaye Creek (5,5, and 7 metric tons per square kilometer, respectively). Drought conditions during the study period appear to have been a factor in the small loads compared to loads measured in the same area in the 1970's. The annual-mean streamflow at the Little Tennessee River at Prentiss during 2001 was about 50 percent of the long-term annual-mean streamflow (1944-2001). High-flow events carry most of the annual sediment load.

North Carolina↗
USGS2001

Annual production of burrowing mayfly nymphs ( Hexagenia spp.) in U.S. waters of Lake St. Clair

Burrowing mayfly nymphs ( Hexagenia spp.) were sampled monthly, September through October 1995 and April through August 1996, with a standard Ponar grab (538 cm 2 jaw opening) at 16 stations in U.S. waters of Lake St. Clair. Annual production (production, P) was 0 to 477 mg dry weight/m 2 at three stations where pollution and sediment grain-size distribution limited the population, and was 738 to 5,255 mg dry weight/m 2 at the other 13 stations. The highest production value measured for Hexagenia in Lake St. Clair was about three times higher than the highest value reported for other areas in the northern United States and Canada (39° to 53° North latitude). The production-mean annual biomass (biomass, B) ratio (P/B) for Hexagenia in Lake St. Clair in 1995–96 was described by the straight line P = 2.4 B (R 2 = 0.94). Adding published P/B data for other North American populations changed the relation only slightly to P = 2.5B (R 2 = 0.96). A P/B ratio of 2.5 is consistent with the expected value for an aquatic insect with a 2-year life cycle and overlapping cohorts, and these data suggest this relation has general applicability for estimating production of Hexagenia in the northern United States and Canada. Size-class and seasonal partitioning of Hexagenia biomass and production were evident in the data. Both biomass and production were highest among nymphs 16.0 mm and larger, and biomass was highest in October and again in June, immediately before the annual emergence of subimagos. The large size of the mature nymphs and the concentration of biomass and production among the larger nymphs in the population is consistent with their importance in the diets of many fishes in the northern United States and Canada.

Lake St. Clair↗
USGS2010

Stream gage descriptions and streamflow statistics for sites in the Tigris River and Euphrates River Basins, Iraq

Statistical summaries of streamflow data for all long-term streamflow-gaging stations in the Tigris River and Euphrates River Basins in Iraq are presented in this report. The summaries for each streamflow-gaging station include (1) a station description, (2) a graph showing annual mean discharge for the period of record, (3) a table of extremes and statistics for monthly and annual mean discharge, (4) a graph showing monthly maximum, minimum, and mean discharge, (5) a table of monthly and annual mean discharges for the period of record, (6) a graph showing annual flow duration, (7) a table of monthly and annual flow duration, (8) a table of high-flow frequency data (maximum mean discharge for 3-, 7-, 15-, and 30-day periods for selected exceedance probabilities), and (9) a table of low-flow frequency data (minimum mean discharge for 3-, 7-, 15-, 30-, 60-, 90-, and 183-day periods for selected non-exceedance probabilities).

Data Series↗
USGS2024

Assessment of long-term changes in surface-water extent within Klamath Marsh, south-central Oregon, 1985–2021

The annual maximum extent of surface water in Klamath Marsh has naturally fluctuated in response to periods of wet and dry conditions in the surrounding basin. Field observations during the 2010s indicate that the annual maximum extent of surface water has been declining and the marsh is not responding to hydrologic inputs as it had historically. This report describes the results of a hydrologic evaluation of Klamath Marsh to characterize and understand multi-year declines in the surface-water extent and increased intermittency of streamflow exiting the marsh. Landsat imagery collected during 1985–2021 was processed to create a time series of annual maximum surface-water extent to assess changes in surface-water inundation within the marsh. A 50-percent decrease in the mean surface area of annual total open-water extent (TOWE) during the latter half of the study period (2003–21) compared to the first half (1985–2003) was observed in this 37-year time-series dataset. The change in open-water extent was offset by a corresponding increase in dry land in the marsh. Time series of streamflow, groundwater level, total annual precipitation, annual mean temperature, and anthropogenic water use and water management were compiled and evaluated to improve understanding of the factors affecting TOWE. Statistically significant downward trends in the regional groundwater table and streamflow into and out of the marsh were identified as well as statistically significant upward trends in annual mean temperature. Statistically significant correlations among TOWE, streamflow, and groundwater level also were identified. The decreasing trends could not be attributed to changes in total annual precipitation or changing anthropogenic groundwater use within the study area. Declines in the open-water extent of Klamath Marsh since 2000 principally are due to a decoupling of the groundwater and surface-water system beneath the marsh because of regional declines in groundwater level. Regional increases in air temperature and the reestablishment of more than 55,000 acres of forested land within the study area have likely contributed to increasing evapotranspiration, leaving less water available for groundwater recharge and stream base flow and resulting in basin-wide declines in streamflow and groundwater levels.

Oregon↗
USGS2011

A multi-year comparison of IPCI scores for prairie pothole wetlands: implications of temporal and spatial variation

In the prairie pothole region of North America, development of Indices of Biotic Integrity (IBIs) to detect anthropogenic impacts on wetlands has been hampered by naturally dynamic inter-annual climate fluctuations. Of multiple efforts to develop IBIs for prairie pothole wetlands, only one, the Index of Plant Community Integrity (IPCI), has reported success. We evaluated the IPCI and its ability to distinguish between natural and anthropogenic variation using plant community data collected from 16 wetlands over a 4-year-period. We found that under constant anthropogenic influence, IPCI metric scores and condition ratings varied annually in response to environmental variation driven primarily by natural climate variation. Artificially forcing wetlands that occur along continuous hydrologic gradients into a limited number of discrete classes (e.g., temporary, seasonal, and semi-permanent) further confounded the utility of IPCI metrics. Because IPCI scores vary significantly due to natural climate dynamics as well as human impacts, methodology must be developed that adequately partitions natural and anthropogenically induced variation along continuous hydrologic gradients. Until such methodology is developed, the use of the IPCI to evaluate prairie pothole wetlands creates potential for misdirected corrective or regulatory actions, impairment of natural wetland functional processes, and erosion of public confidence in the wetland sciences.

Wetlands↗
USGS2017

Trends in the quality of water in New Jersey streams, water years 1971–2011

In a study conducted by the U.S. Geological Survey in cooperation with the New Jersey Department of Environmental Protection and the Delaware River Basin Commission, trend tests were conducted on selected water-quality characteristics measured at stations on streams in New Jersey during selected periods over water years 1971‒2011. Tests were conducted on 3 nutrients (total nitrogen, filtered nitrate plus nitrite, and total phosphorus) at 28 water-quality stations. At 4 of these stations, tests were also conducted on 3 measures of major ions (specific conductance, filtered chloride, and total dissolved solids). Two methods were used to identify trends—Weighted Regressions on Time, Discharge, and Season (WRTDS) models and seasonal rank-sum tests. For this report, the use of WRTDS models included the use of the WRTDS Bootstrap Test (WBT). WRTDS models identified trends in flow-normalized annual concentrations and flow-normalized annual fluxes over water years 1980‒2011 and 2000‒11 for each nutrient, filtered chloride, and total dissolved solids. WRTDS models were developed for each nutrient at the 20 or 21 stations at which streamflow was measured or estimated. Trends in nutrient concentration were reported for these stations; trends in nutrient fluxes were reported only for 15–17 of these stations. The results of WRTDS models for water years 1980‒2011 identified more stations with downward trends in concentrations of either total nitrogen or total phosphorus than upward trends. For total nitrogen, there were downward trends at 9 stations and an upward trend at 1 station. For total phosphorus, there were downward trends at 8 stations and an upward trend at 1 station. For filtered nitrate plus nitrite, there were downward trends at 6 stations and upward trends at 6 stations. The result of the trend test in flux for a selected nutrient at a selected station (downward trend, no trend, or upward trend) usually matched the trend result in concentration. Seasonal rank-sum tests, the second method used, identified step trends in water-quality measured in different decades—1970s, 1980s, 1990s, and 2000s. Tests were conducted on all nutrients at 28 stations and on all measures of major ions at the 4 selected stations. Results of seasonal rank-sum tests between the 1980s and the 2000s identified more stations with downward trends in concentrations of total nitrogen (14) than stations with upward trends (2) and more stations with downward trends in concentrations of total phosphorus (18) than stations with upward trends (1). A combined dataset of trend results for concentrations over water years 1980‒2011 was created from the results of the two tests for the period. Results of WRTDS models were included in this combined dataset, if available. Otherwise, the results of the seasonal rank-sum tests between water-quality characteristics measured in the 1980s and 2000s were included. Trend results over water years 1980‒2011 in the combined dataset show that few of the 28 stations had upward trends in concentrations of either total nitrogen or total phosphorus. There were only 2 stations with upward trends in total nitrogen concentration and 1 station with an upward trend in total phosphorus concentration. Results for filtered nitrate plus nitrite show about the same number of stations with upward trends (9) as stations with downward trends (7). Results for all measures of major ions show upward trends at the four stations tested.

New Jersey↗
USGS1995

Statistical characteristics of stream discharge in tributaries of selected estuaries in southern New Jersey

This report presents the results of a study, done in cooperation with the New Jersey Department of Environmental Protection, to analyze the characteristics of stream discharge for tributaries of the estuaries of the Metedeconk, Toms, Great Egg Harbor, Tuckahoe, and Maurice Rivers. The following statistics were calculated for selected streamflow-gaging stations: (1) mean annual and mean monthly discharge, and (2) lowest annual 7-day mean discharge for selected recurrence intervals.Values of lowest annual 7-day mean discharge were calculated for the entire year and for the 3-, 4-, 5-, and 6-month periods of greatest tributary discharge. The monthly variation in discharge was examined. Values of discharge at different stations were converted to runoff and compared; runoff is expressed as discharge per unit area of drainage for a given period. Tests for trend were conducted on values of monthly discharge and lowest annual discharges at continuous-record stations. Statistics were determined from discharge records of the U.S. Geological Survey. The monthly variation in discharge is similar for most streams in the study area; discharge is greatest during March and April and least during August, September, and October. The 3-, 4-, 5-, and 6-month periods of greatest discharge are February through April, January through April, January through May, and December through May, respectively. Mean annual runoff is greater in the tributaries of the Metedeconk and Toms River estuaries than in the tributaries of the other estuaries. Runoff in tributaries of these two basins ranges from 24 to 29 inches per year; the corresponding range for tributaries of the other estuaries is 16 to 23 inches per year. Trend analysis showed that values of lowest annual discharges at continuous-record stations on tributaries of all five estuaries decreased during water years 1970-89. For four stations, values of 183-day lowest annual discharge during the complete year decreased; for three of lowest annual 7- or 30-day mean discharge during the 3-, 4-, 5-, and 6-month periods of greatest discharge decreased. There were no trends in monthly discharge for water years 1970-89. For other periods tested, there were no trends either in lowest annual discharges or monthly discharges. Discharge statistics at the heads of tide were calculated from the period-of-record characteristics at continuous-record stations and characteristics determined for partial-record stations. Results show that discharge at the heads of tide of the estuaries is directly related to the drainage area.Drainage areas and discharge are greatest for the Great Egg Harbor and Maurice Rivers, whose mean annual discharges are 340 and 310 cubic feet per second, respectively. Mean annual discharges of the Toms and Metedeconk Rivers are 220 and 140 cubic feet per second, respectively. Drainage area and discharge of the Tuckahoe River are the smallest of the estuaries studied; mean annual discharge is 43.9 cubic feet per second.

New Jersey↗