Geology topics

Alana B. Spaetzel

Publications and source records attributed to Alana B. Spaetzel.

8 recordsLinked to original sources

USGS2025

Nitrate loads and concentrations from forested watersheds and implications for Long Island Sound

Reduction in point sources of nitrogen has led to improvement in water quality of the Long Island Sound (LIS) since 2000, but changes in nonpoint sources are less clear. A significant yet poorly quantified nonpoint nitrogen source is the forested landscape. Because a large proportion of the LIS basin is forested, even small areal inputs from the forested landscape have a large cumulative effect on nitrogen loading to LIS. Atmospheric nitrogen deposition, the primary source of nitrogen to forested landscapes in LIS basin, has been declining for several decades. However, nitrogen export in streams does not necessarily mirror nitrogen deposition. To assess forest nitrogen export to LIS, we estimated annual average concentrations and fluxes of nitrate in 17 forested watersheds in and near the LIS basin. Average flow-normalized nitrate-nitrogen concentrations ranged from less than 0.05–0.43 mg per liter among all sites; annual flow-normalized yields ranged from 0.45 to 4.3 kg per hectare. Flow-normalized annual average concentrations and yields of nitrate between water years 1991–2021 did not monotonically increase or decrease at most watersheds. Where determined, the other major N species generally had comparable magnitude and trends. Based on the watersheds analyzed in this study, forested areas are not responding uniformly to the continued decline of atmospheric nitrogen deposition. The variability among sites may indicate that local-scale factors exert substantial influence over the magnitude and trends in nitrogen exports. One watershed that had increasing development showed an increasing trend in nitrate, but not in dissolved organic nitrogen.

Connecticut, Massachusetts, New Hampshire, New Yor↗

USGS2025

Streamflow, water quality, and constituent loads and yields, Scituate Reservoir drainage area, Rhode Island, water year 2022

As part of a long-term cooperative program to monitor water quality within the Scituate Reservoir drainage area, the U.S. Geological Survey, in cooperation with Providence Water (formerly the Providence Water Supply Board), collected streamflow and water-quality data in tributaries to the Scituate Reservoir, Rhode Island. Streamflow and concentrations of chloride and sodium estimated from records of specific conductance for 16 tributaries were used to calculate loads of chloride and sodium during water year 2022 (October 1, 2021, through September 30, 2022). Water-quality samples were collected by Providence Water at 37 sampling stations on tributaries to the Scituate Reservoir during water year 2022. These water-quality data are summarized by using values of central tendency and are used, in combination with measured (or estimated) streamflows, to calculate loads and yields of selected water-quality constituents for water year 2022. Annual mean streamflows for monitoring stations in this study ranged from about 0.31 to 28.0 cubic feet per second during water year 2022. At the 16 continuous-record streamgages, tributaries transported about 2,600 metric tons of chloride and 1,600 metric tons of sodium to the Scituate Reservoir; annual chloride yields for the tributaries ranged from 15 to 100 metric tons per square mile, and annual sodium yields ranged from 10 to 59 metric tons per square mile. At the stations where water-quality samples were collected by Providence Water, the medians of the median daily loads were 55,000 million colony forming units per day for coliform bacteria, 1,300 million colony forming units per day for Escherichia coli , 230 kilograms per day for chloride, 11 grams per day as nitrogen for nitrite, 620 grams per day as nitrogen for nitrate, and 440 grams per day as orthophosphate for phosphate, The medians of the median yields were 25,000 million colony forming units per day per square mile for coliform bacteria, 810 million colony forming units per day per square mile for Escherichia coli , 110 kilograms per day per square mile for chloride, 5.1 grams per day per square mile as nitrogen for nitrite, less than 300 grams per day per square mile as nitrogen for nitrate, and 230 grams per day per square mile as orthophosphate for phosphate.

Rhode Island↗

USGS2024

Streamflow, water quality, and constituent loads and yields, Scituate Reservoir drainage area, Rhode Island, water year 2021

As part of a long-term cooperative program to monitor water quality within the Scituate Reservoir drainage area, the U.S. Geological Survey in cooperation with Providence Water (formerly Providence Water Supply Board) collected streamflow and water-quality data in tributaries to the Scituate Reservoir, Rhode Island. Streamflow and concentrations of chloride and sodium estimated from records of specific conductance for 16 tributaries were used to calculate loads of chloride and sodium during water year 2021 (October 1, 2020, through September 30, 2021). Water-quality samples were collected by Providence Water at 36 sampling stations on tributaries to the Scituate Reservoir during water year 2021. These water-quality data are summarized by using values of central tendency and are used, in combination with measured (or estimated) streamflows, to calculate loads and yields of selected water-quality constituents for water year 2021. Annual mean streamflows for monitoring stations in this study ranged from 0.37 to 32.4 cubic feet per second during water year 2021. At the 16 continuous-record streamgages, tributaries transported about 2,900 metric tons (t) of chloride and 1,800 t of sodium to the Scituate Reservoir; annual chloride yields for the tributaries ranged from 15 to 110 metric tons per square mile (t/mi 2 ), and annual sodium yields ranged from 10 to 68 t/mi 2 . At the stations where water-quality samples were collected by Providence Water, the medians of the median daily loads were 180 kilograms per day for chloride, 12 grams per day as nitrogen for nitrite, less than 700 grams per day as nitrogen for nitrate, 410 grams per day as orthophosphate for phosphate, 71,000 million colony forming units per day for coliform bacteria, and less than 2,000 million colony forming units per day for Escherichia coli . The medians of the median yields were 67 kilograms per day per square mile for chloride, 4.2 grams per day per square mile as nitrogen for nitrite, 400 grams per day per square mile as nitrogen for nitrate, 180 grams per day per square mile as orthophosphate as phosphate, 46,000 million colony forming units per day per square mile for coliform bacteria, and 1,000 million colony forming units per day per square mile for Escherichia coli .

Rhode Island↗

USGS2023

Highway-runoff quality from segments of open-graded friction course and dense-graded hot-mix asphalt pavement on Interstate 95, Massachusetts, 2018–21

Highway runoff is a source of sediment and associated constituents to downstream waterbodies that can be managed with the use of stormwater-control measures that reduce sediment loads. The use of open-graded friction course (OGFC) pavement has been identified as a method to reduce loads from highway runoff because it retains sediment in pavement voids; however, few datasets are available in New England to characterize runoff quality from OGFC pavement. To meet this data need, the U.S. Geological Survey, in cooperation with the Massachusetts Department of Transportation, conducted a field study from October 2018 through September 2021 to monitor runoff from a section of traditional dense-graded hot-mix asphalt (HMA) and from a section of OGFC pavement on Interstate 95 near Needham, Massachusetts. A robust dataset that includes suspended sediment concentrations for nearly every runoff event during the study period was generated to compare runoff from the two 4,180-square-foot sections of highway pavement under identical traffic volume and maintenance characteristics. Automatic-monitoring techniques were used to collect over 6,500 samples at each station to characterize all runoff-generating events during the study period (226 events for the HMA site and 168 events for the OGFC site). Suspended sediment concentrations were consistently lower in runoff from the OGFC pavement throughout the study period, with median event-mean concentrations for all runoff events of 29 and 15 milligrams per liter for the HMA and OGFC sites, respectively. The total load of sediment less than 6.0 millimeters in diameter from the HMA section (202 kilograms [kg]) was 41 percent greater than the load measured from the OGFC pavement (120 kg), and the total load of sediment less than 2.0 mm in diameter was 49 percent greater (168 kg and 85 kg from the HMA and OGFC sites, respectively). The greatest differences in loads between the two pavement segments were in the particle-size ranges less than 2.0 millimeters in diameter, indicating that these particles are retained by the voids in the OGFC pavement. The relative difference between annual sediment-load estimates at each site over the study period indicates that OGFC pavement became clogged, a condition that permeameter test results also reflected. Specifically, the average total load of sediment for the first 2 years of the study was 68 percent lower at the OGFC site than the HMA site, but the difference between the respective loads decreased to 19 percent in the third year of the study. Study-period loads for most total-recoverable metals in runoff from each pavement type were between 7 and 64 percent higher from the HMA site, except for loads of arsenic, cadmium, and zinc, which were higher from the OGFC pavement. Study-period loads for total phosphorus were similar from each pavement type. Despite the same application rate of deicing chemicals, sodium and chloride loads in runoff were about two times greater from the OGFC section than from the HMA pavement during years with average snowfall amounts but were approximately equal at both sites during the mild winter in 2020.

Massachusetts↗

USGS2023

Approaches for assessing flows, concentrations, and loads of highway and urban runoff and receiving-stream stormwater in southern New England with the Stochastic Empirical Loading and Dilution Model (SELDM)

The Stochastic Empirical Loading and Dilution Model (SELDM) was designed to help quantify the risk of adverse effects of runoff on receiving waters, the potential need for mitigation measures, and the potential effectiveness of such management measures for reducing these risks. SELDM is calibrated using representative hydrological and water-quality input statistics. This report by the U.S. Geological Survey, in cooperation with the Federal Highway Administration and the Connecticut, Massachusetts, and Rhode Island Departments of Transportation, documents approaches for assessing flows, concentrations, and loads of highway- and urban-runoff and receiving-stream stormwater in southern New England with SELDM. In this report, the term “urban runoff” is used to identify stormwater flows from developed areas with impervious fractions ranging from 10 to 100 percent without regard to the U.S. Census Bureau designation for any given location. There are more than 48,000 delineated road-stream crossings in southern New England, but because there are relatively few precipitation, streamflow, and water-quality monitoring sites in this area, methods were needed to simulate conditions at unmonitored sites. This report documents simulation methods, methods for interpreting stochastic model results, sensitivity analyses to identify the most critical variables of concern, and examples demonstrating how simulation results can be used to inform scientific decision-making processes. Results of 7,511 SELDM simulations were used to do the sensitivity analyses and provide information decisionmakers can use to address runoff-quality issues in southern New England and other areas of the Nation. The sensitivity analyses indicate the relatively strong effect of input variables on variations in output results. These analyses indicate that highway and urban runoff quality and upstream water-quality statistics that vary considerably from site to site have the greatest effect on simulated results. Further data are needed to improve available water-quality statistics, and because the number of monitored sites will never approach the number of sites of interest for water-quality management, research is needed to identify methods to select statistics for unmonitored sites and quantify the uncertainties in the selection process. Hydrologically, prestorm streamflows with and without zero flows are the most sensitive and therefore the most important hydrologic variables to quantify. Results of analyses also are sensitive to statistics used for simulating structural best management practices. Although the focus of the report is on data, statistics, simulation methods, and methods to interpret stochastic simulations, the examples in this report provide results that can be used to inform scientific decision-making processes. The results of 441 simulations that provide regional and site-specific highway and urban runoff yields across southern New England can be used for total maximum daily load analyses. The example stormwater load analysis done for 16 tributaries of the Narragansett Bay demonstrates that highway nitrogen loads are a small fraction of stormwater loads (about 3.6 percent), and a much smaller fraction of all nitrogen loads to the bay, primarily because highways have a small footprint on the land. Examples evaluating the potential effectiveness of end-of-pipe treatment indicate that offsite treatment is warranted in developed areas, and land conservation may be an effective mitigation strategy. The results of these analyses are consistent with conclusions from other simulation and monitoring studies.

Connecticut, Massachusetts, New Hampshire, Rhode I↗

USGS2022

Water-quality conditions and constituent loads, water years 2013–19, and water-quality trends, water years 1983–2019, in the Scituate Reservoir drainage area, Rhode Island

The Scituate Reservoir is the primary source of drinking water for more than 60 percent of the population of Rhode Island. From October 1, 1982, to September 30, 2019, water years (WYs) 1983–2019 (a water year is the period between October 1 and September 30 and is designated by the year in which it ends), the Providence Water Supply Board maintained a fixed-frequency sampling program at 37 stations to monitor water quality in tributaries to the Scituate Reservoir. The U.S. Geological Survey (USGS), in cooperation with the Providence Water Supply Board, has measured streamflow at selected streamgages in the Scituate Reservoir drainage area since WY 1994, monitored water quality at selected stations since WY 2009, and conducted targeted base-flow and stormflow sampling at five stations in WYs 2016–19. Daily loads and yields of constituents (chloride, nitrite, nitrate, total coliform bacteria, Escherichia coli , and orthophosphate) were determined for sampled days during WYs 2013–19, and trends were examined for the entire period of record, predominantly WYs 1983–2019. USGS water-quality data were used to determine annual loads and yields of chloride and sodium for WYs 2013–19 at 14 stations, and nutrients and suspended sediment for WYs 2016–19 at 5 stations. Tributaries in the Scituate Reservoir drainage area for WYs 2013–19 were slightly acidic (pH values less than 7.0 standard units) and often below the recommended pH range of 6.5 to 8.5 standard units, as described by the U.S. Environmental Protection Agency (EPA) in the secondary drinking-water regulations. Most measurements of water color in the tributaries were greater than the EPA secondary drinking-water regulation of 15 platinum-cobalt units. Chloride concentrations in Providence Water Supply Board samples rarely exceeded the EPA secondary drinking-water regulation for chloride (250 milligrams per liter); however, chloride concentrations estimated from continuous measurements of specific conductance exceeded the EPA criterion continuous concentration recommended for freshwater (230 milligrams per liter) for short periods ranging from 10 minutes to 26 hours at two streamgages. Positive trends in pH, color, alkalinity, and chloride at more than half of the monitoring stations were identified for WYs 1983–2019. Fewer than half of the stations had significant trends in turbidity values, and significant trends varied in direction (positive or negative trends). Trend tests were not performed on total coliform bacteria, Escherichia coli , and nitrate concentrations because of analytical method changes that coincide with abrupt shifts in the magnitude and distribution of concentration data. The median of daily loads and yields of chloride, nitrite, nitrate, orthophosphate, and bacteria determined for each Providence Water Supply Board sample in WYs 2013–19 varied across the 37 monitoring stations, but yields were generally greater at stations in the Moswansicut and Regulating Reservoir subbasins. Average daily yields of chloride and sodium estimated from continuous records of specific-conductance and streamflow data at 14 stations ranged from 42 to 310 kilograms per square mile per day and 28 to 180 kilograms per square mile per day, respectively. The mean annual yields of total phosphorus, total nitrogen, and suspended sediment determined for five stations ranged from 16 to 78 kilograms per square mile, from 370 to 2,100 kilograms per square mile, and from 5,000 to 13,000 kilograms per square mile, respectively. More than half of the nutrient and suspended sediment loads occurred during stormflow.

Rhode Island↗

USGS2021

Assessment of water quality and discharge in the Herring River, Wellfleet, Massachusetts, November 2015 to September 2017

The U.S. Geological Survey, Cape Cod National Seashore of the National Park Service, and Friends of Herring River cooperated from 2015 to 2017 to assess nutrient concentrations and fluxes across the ocean-estuary boundary at a dike on the Herring River in Wellfleet, Massachusetts. The purpose of this assessment was to characterize environmental conditions prior to a future removal of the dike, which has restricted saltwater inputs into the Herring River watershed for more than 100 years. Water temperature, dissolved oxygen, pH, and specific conductance were monitored continuously, and flow-weighted composite samples were collected approximately twice per month at the ocean-estuary boundary. Bidirectional discharge was computed for the U.S. Geological Survey Herring River at Chequessett Neck Road at Wellfleet, Massachusetts, streamgage (011058798) by using a stage-area rating and index-velocity ratings developed with acoustic Doppler current profile measurements made upstream and downstream from the dike. LOADEST regression modeling software was used to estimate nutrient fluxes (loads) from composite, paired nutrient concentration and discharge data in conjunction with continuous discharge data. Temperature, dissolved oxygen, pH, and specific conductance were also monitored continuously on two tributaries to the Herring River, Pole Dike Creek and Bound Brook, from late-May 2016 to mid-June 2017. Composite or discrete water samples were collected from the tributaries approximately twice per month in most months from late-May 2016 to mid-June 2017 and analyzed for total nitrogen, total phosphorus, and dissolved organic carbon. Flow-weighted concentrations of ammonium, nitrate, and total nitrogen on the Herring River at the dike on the ebb tide generally varied between 0.01 and 0.1, 0.003 and 0.03, and 0.3 and 0.7 milligram per liter as nitrogen, respectively. Flow-weighted concentrations of orthophosphate, total dissolved phosphorus, and total phosphorus generally varied between 0.002 and 0.02, 0.003 and 0.06, and 0.03 and 0.1 milligram per liter as phosphorus, respectively, on the ebb tide. Flow-weighted concentrations of silicate and dissolved organic carbon on the ebb tide generally varied between 0.08 and 3.0 milligrams per liter of silica (silicon dioxide), and 1.7 and 5.6 milligrams per liter of carbon, respectively. Ebb tide concentrations of nitrate were highest in winter and lowest in summer. By contrast, ebb tide concentrations of phosphorus species were highest in late summer and early fall and lowest in winter. Silica and dissolved organic carbon did not exhibit systematic variation in seasonal concentrations. There was uncertainty in estimates of nutrient fluxes, but the LOADEST-estimated fluxes indicated that annual (and in almost all cases seasonal) exports (ebb tides) exceeded inputs (flood tides). Ebb tide concentrations of ammonium, nitrate, total nitrogen, and silica were positively correlated with antecedent cumulative 7-day precipitation.

Massachusetts↗

USGS2021

Statistical methods for simulating structural stormwater runoff best management practices (BMPs) with the Stochastic Empirical Loading and Dilution Model (SELDM)

This report documents statistics for simulating structural stormwater runoff best management practices (BMPs) with the Stochastic Empirical Loading and Dilution Model (SELDM). The U.S. Geological Survey developed SELDM and the statistics documented in this report in cooperation with the Federal Highway Administration to indicate the risk for stormwater flows, concentrations, and loads to exceed user-selected water-quality goals and the potential effectiveness of mitigation measures to reduce such risks. In SELDM, three treatment variables—hydrograph extension, volume reduction, and water-quality treatment—are simulated by using the trapezoidal distribution and the rank correlation with the associated runoff variables. This report describes methods for calculating the trapezoidal distribution statistics and rank correlation coefficients for these treatment variables and methods for estimating the minimum irreducible concentration (MIC), which is the lowest expected effluent concentration from a BMP site or a category of BMPs. These statistics are different from the statistics commonly used to characterize or compare BMPs; they are designed to provide a stochastic transfer function to approximate the quantity, duration, and quality of BMP effluent given the associated inflow values for a population of storm events. Analyses for this study were done with data extracted from a modified copy of the December 2019 version of the International Stormwater Best Management Practices Database. Statistics for volume reduction, hydrograph extension, and water-quality treatment were developed with selected data. The medians of the best-fit statistics for selected constituents were used to construct generalized cumulative distribution functions for the three treatment variables. For volume reduction and hydrograph extension, selection of a Spearman’s rank correlation coefficient (rho) value that is the average of the median and maximum values for the BMP category may help generate realistic simulation results in SELDM. The median rho value may be selected to help generate realistic simulation results for water-quality treatment variables. Water-quality treatment statistics, including trapezoidal ratios and MIC values, were developed for 51 runoff-quality constituents commonly measured in highway and urban runoff studies. Statistics were calculated for water-quality properties, sediment and solids, nutrients, major and trace inorganic elements, organic compounds, and biologic constituents. Analysis of MIC values provides information to guide professional judgement for selecting values for simulating water quality at sites of interest. The MIC is a lower bound for BMP discharge concentrations and will therefore replace simulated BMP discharge concentrations below the selected value. A new method for estimating MIC values, the lognormal variate of inflow concentrations, was developed in this report and these statistics were calculated for individual constituents and constituent categories. Inflow quality is correlated to MIC values for some constituents, but regional soil concentrations were not strongly correlated to MIC values.

Scientific Investigations Report↗