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At least 91 records · Page 5Linked to original sources
USGS2005

Exposure and effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin in tree swallows (Tachycineta bicolor) nesting along the Woonasquatucket River, Rhode Island, USA

Concentrations of 2,3,7,8-tetrachlorodibenzo- p -dioxin (TCDD) in tree swallows ( Tachycineta bicolor ) nesting along the Woonasquatucket River northwest of Providence (RI, USA) in 2000 and 2001 were some of the highest ever reported in avian tissues. Mean concentrations in eggs ranged from 300 to > 1,000 pg/g wet weight at the two most contaminated ponds, Allendale and Lyman. Mean egg concentrations at Greystone, the upstream reference pond, were 12 and 29 pg/g. Positive accumulation rates and concentrations in diet samples from 12-day-old nestlings indicated that the contamination was accumulated locally. Concentrations in diet of between 71 and 219 pg/g wet weight were more than 6 and 18 times higher than concentrations considered safe for birds (10–12 pg/g). Hatching success was negatively associated with concentration of TCDD in eggs. Only about half the eggs hatched at Allendale compared with >77% at Greystone. The national average for hatching success in successful nests is 85%. No other contaminants, such as polychlorinated biphenyls and mercury, were present in any sample at concentrations known to affect avian reproduction. Three bioindicators, half-peak coefficient of geometric variation, ethoxyresorufin- O -dealkylase activity, and brain asymmetry were assessed relative to TCDD contamination.

Rhode Island↗
USGS2005

Estimated water use and availability in the South Coastal Drainage Basin, southern Rhode Island, 1995-99

The South Coastal Drainage Basin includes approximately 59.14 square miles in southern Rhode Island. The basin was divided into three subbasins to assess the water use and availability: the Saugatucket, Point Judith Pond, and the Southwestern Coastal Drainage subbasins. Because there is limited information on the ground-water system in this basin, the water use and availability evaluations for these subbasins were derived from delineated surface-water drainage areas. An assessment was completed to estimate water withdrawals, use, and return flow over a 5-year study period from 1995 through 1999 in the basin. During the study period, one major water supplier in the basin withdrew an average of 0.389 million gallons per day from the sand and gravel deposits. Most of the potable water is imported (about 2.152 million gallons per day) from the adjacent Pawcatuck Basin to the northwest. The estimated water withdrawals from the minor water suppliers, which are all in Charlestown, during the study period were 0.064 million gallons per day. The self-supplied domestic, industrial, commercial, and agricultural withdrawals from the basin were 0.574 million gallons per day. Water use in the basin was 2.874 million gallons per day. The average return flow in the basin was 1.190 million gallons per day, which was entirely from self-disposed water users. In this basin, wastewater from service collection areas was exported (about 1.139 million gallons per day) to the Narragansett Bay Drainage Basin for treatment and discharge. During times of little to no recharge, in the form of precipitation, the surface- and ground-water system flows are from storage primarily in the stratified sand and gravel deposits, although there is flow moving through the till deposits at a slower rate. The ground water discharging to the streams, during times of little to no precipitation, is referred to as base flow. The PART program, a computerized hydrograph-separation application, was used at the selected index stream-gaging station to determine water availability based on the 75th, 50th, and 25th percentiles of the total base flow, the base flow minus the 7-day, 10-year flow criteria, and the base flow minus the Aquatic Base Flow criteria at the index station. The base flow calculated at the selected index station was subdivided into two rates on the basis of the percent contributions from sandand-gravel and till deposits. There has been no long-term collection of surface-water data in this study area and therefore an index stream-gaging station in the Pawcatuck Basin was used for the South Coastal Drainage Basin. The Pawcatuck River at Wood River Junction was chosen as the index station for the South Coastal Drainage Basin because the station is representative of the basin on the basis of the percentage of sand and gravel deposits and the average extent of thickness of the sand and gravel deposits. The baseflow contributions from sand and gravel deposits at the index station were computed for June, July, August, and September, and applied to the percentage of surficial deposits at the index station. The base-flow contributions were converted to a per unit area at the station for the till, and for the sand and gravel deposits and applied to the South Coastal Drainage Basin to determine the water availability. The results from the index station, the Pawcatuck River at Wood River Junction streamgaging station, were lowest for the summer in September. To determine water availability in the South Coastal Drainage Basin, the per unit area of the estimated base flows from sand and gravel deposits and till deposits at the index station was applied to the subbasin areas, and the resultant flows were lowest in September. The base flow at the 75th percentile in the basin was 56.95 million gallons per day in June; 32.78 million gallons per day in July; 30.22 million gallons per day in August; and 23.94 million gallons per day in September. The base flow at the 50th percentile in the basin was 44.59 million gallons per day in June; 25.31 million gallons per day in July; 20.75 million gallons per day in August; and 17.01 million gallons per day in September. The base flow at the 25th percentile in the basin was 35.52 million gallons per day in June; 20.40 million gallons per day in July; 14.94 million gallons per day in August; and 12.00 million gallons per day in September. There are some limitations in the application of this method along the coast, because saltwater intrusion can change the amount of fresh ground-water discharge to the coastal saltwater ecosystem. A ground-water system analysis evaluating these variances would provide additional information to assess the water availability along the coast. Because water withdrawals and use are greater during the summer than other times of the year, water availability in June, July, August, and September was assessed and compared to water withdrawals in the basin. The ratios were calculated by dividing the water withdrawals by the water-availability flow scenarios at the 75th, 50th, and 25th percentiles for the basin, which are based on total water available from base-flow contributions from till and sand and gravel deposits in the basin. The closer the ratio is to one, the closer the withdrawals are to the estimated water available, and the net water available decreases. For the study period, the withdrawals in July were higher than the other summer months. The ratios in the basin for the base-flow scenario, with no low-flow criteria removed, ranged from 0.029 to 0.046 in June; 0.059 to 0.094 in July; 0.050 to 0.100 in August; and 0.040 to 0.079 in September. A long-term hydrologic budget (60 years) was calculated for the South Coastal Drainage Basin to identify and assess the basin and subbasin inflow and outflows. This coastal basin is different than other study areas because all three of the subbasins drain into salt water, Point Judith Point, Long Island Sound, and Rhode Island Sound towards the Atlantic Ocean, or internally within the subbasin to the salt ponds. The hydrologic budgets, therefore, were compiled by subbasin. The basin hydrologic budget is the sum of the three subbasin budgets. Unlike a river subbasin drainage system, however, the estimated streamflows out of the subbasins were also considered outflows from the basin. The water withdrawals and return flows used in the budget were from 1995 through 1999. For the hydrologic budget, it was assumed that inflow equals outflow, where the estimated inflows were from precipitation and wastewater-return flow, and the estimated outflows were from evapotranspiration, streamflow, and water withdrawals.

Rhode Island↗
USGS2005

Water use and availability in the Woonasquatucket and Moshassuck River basins, north-central Rhode Island

The Woonasquatucket River Basin includes 51.0 square miles, and the Moshassuck River Basin includes 23.8 square miles in north-central Rhode Island. The study area comprises these two basins. The two basins border each other with the Moshassuck River Basin to the northeast of the Woonasquatucket River Basin. Seven towns are in the Woonasquatucket River Basin, and six towns are in the Moshassuck River Basin. To determine the water use and availability in the study area, water supply and discharge data were collected for these river basins for the 1995–99 period, and compared to estimated long-term water available. The study area is unique in the State of Rhode Island, because no withdrawals from major public suppliers were made during the study period. Withdrawals were, therefore, limited to self-supplied domestic use, two minor suppliers, and one self-supplied industrial user. Because no metered data were available, the summer water withdrawals were assumed to be the same as the estimates for the rest of the year. Seven major water suppliers distribute an average of 17.564 million gallons per day for use in the study area from sources outside of the study area. The withdrawals from minor water suppliers were 0.017 million gallons per day in the study area, all in the town of Smithfield in the Woonasquatucket River Basin. The remaining withdrawals in the study area were estimated to be 0.731 million gallons per day by self-supplied domestic, commercial, industrial, and agricultural users. Return flows in the study area included self-disposed water and disposal from permitted dischargers, including the Smithfield Sewage Treatment Plant. Return flows accounted for 4.116 million gallons per day in the study area. Most public-disposed water (15.195 million gallons per day) is collected by the Narragansett Bay Commission and is disposed outside of the basin in Narragansett Bay. The PART program, a computerized hydrograph-separation application, was used at one index stream-gaging station to determine water availability based on the 75th, 50th, and 25th percentiles of the total base flow, the base flow minus the 7-day, 10-year flow criteria, and the base flow minus the Aquatic Base Flow criteria. The index station selected was the Branch River at Forestdale, which is close to the study area and has a similar percentage of sand and gravel area. Water availability was estimated on the basis of baseflow contributions from sand and gravel deposits and till deposits at the index station. Flows were computed for June, July, August, and September 1957–2000, and a percentage of the total flow was determined to come from either sand and gravel deposits, or till, by using a regression equation. The base-flow contributions were converted to a flow per unit area at the station for the till and for the sand and gravel deposits and then applied to the deposits in the study area basins. These values were used to estimate the gross yield of base flow, as well as to subtract the two low flows (7-day, 10-year flow, and Aquatic Base Flow criteria). The results from the Branch River stream-gaging station were lowest in August at the 75th, 50th, and 25th percentile for total flow with either flow criteria subtracted. The estimated August gross yield at the 50th percentile from the Woonasquatucket River Basin was 12.94 million gallons per day, and 5.91 million gallons per day from the Moshassuck River Basin. A ratio was calculated that is equal to total withdrawals divided by water availability. Water-availability flow scenarios at the 75th, 50th, and 25th percentiles for the basins, which are based on total water available from base-flow contributions from till and sand and gravel deposits in the basins, were assessed. The ratios were the highest in July for the 50th percentile estimated gross yield minus Aquatic Base Flow (ABF) flow criteria, where withdrawals are close to the available water. Ratios are not presented if the available water is less than the flow criteria. The ratio of withdrawals to the July gross yield at the 50th percentile minus Aquatic Base Flow was 0.796 for the Woonasquatucket and 0.275 for the Moshassuck River Basin. A long-term hydrologic budget was calculated for the period of 1956–2000 for the Woonasquatucket River Basin and the period of 1964–2000 for the Moshassuck River Basin. The water withdrawals and return flows used in the budget were from 1995 through 1999. For the hydrologic budget, inflow was assumed to equal outflow and was about 120 million gallons per day in the Woonasquatucket River Basin and 56 million gallons per day in the Moshassuck River Basin. The estimated inflows from precipitation and water return flow were 97.3 and 2.7 percent, respectively, in the Woonasquatucket River Basin, and 98.3 and 1.7 percent, respectively, in the Moshassuck River Basin. The estimated outflows from evapotranspiration, streamflow, and water withdrawals were 43.4, 56.1, and 0.5 percent, respectively, in the Woonasquatucket River Basin, and 49.8, 50, and 0.2 percent, respectively, in the Moshassuck River Basin.

Rhode Island↗
USGS2004

A precipitation-runoff model for the analysis of the effects of water withdrawals and land-use change on streamflow in the Usquepaug–Queen River Basin, Rhode Island

The 36.1-square-mile Usquepaug–Queen River Basin in south-central Rhode Island is an important water resource. Streamflow records indicate that withdrawals may have diminished flows enough to affect aquatic habitat. Concern over the effect of withdrawals on streamflow and aquatic habitat prompted the development of a Hydrologic Simulation Program–FORTRAN (HSPF) model to evaluate the water-management alternatives and land-use change in the basin. Climate, streamflow, and water-use data were collected to support the model development. A logistic-regression equation was developed for long-term simulations to predict the likelihood of irrigation, the primary water use in the basin, from antecedent potential evapotranspiration and precipitation for generating irrigation demands. The HSPF model represented the basin by 13 pervious-area and 2 impervious-area land-use segments and 20 stream reaches. The model was calibrated to the period January 1, 2000 to September 30, 2001, at three continuous streamflow-gaging stations that monitor flow from 10, 54, and 100 percent of the basin drainage area. Hydrographs and flow-duration curves of observed and simulated discharges, along with statistics compiled for various model-fit metrics, indicate a satisfactory model performance. The calibrated HSPF model was modified to evaluate streamflow (1) under no withdrawals to streamflow under current (2000–01) withdrawal conditions under long-term (1960–2001) climatic conditions, (2) under withdrawals by the former Ladd School water-supply wells, and (3) under fully developed land use. The effects of converting from direct-stream withdrawals to ground-water withdrawals were evaluated outside of the HSPF model by use of the STRMDEPL program, which calculates the time delayed response of ground-water withdrawals on streamflow depletion. Simulated effects of current withdrawals relative to no withdrawals indicate about a 20-percent decrease in the lowest mean daily streamflows at the basin outlet, but withdrawals have little effect on flows that are exceeded less than about 90 percent of the time. Tests of alternative model structures to evaluate model uncertainty indicate that the lowest mean daily flows ranged between 3 and 5 cubic feet per second (ft3/s) without withdrawals and 2.2 to 4 ft3/s with withdrawals. Changes in the minimum daily streamflows are more pronounced, however; at the upstream streamflow-gaging station, a minimum daily flow of 0.2 ft3/s was sustained without withdrawals, but simulations with withdrawals indicate that the reach would stop flowing part of a day about 5 percent of the time. The effect on streamflow of potential ground-water withdrawals of 0.20, 0.90, and 1.78 million gallons per day (Mgal/d) at the former Ladd School near the central part of the basin were evaluated. The lowest daily mean flows in model reach 3, the main stem of the Queen River closest to the pumped wells, decreased by about 50 percent for withdrawals of 0.20 Mgal/d (from about 0.4 to 0.2 ft3/s) in comparison to current withdrawals. Reach 3 would occasionally stop flowing during part of the day at the 0.20-Mgal/d withdrawal rate because of diurnal fluctuation in streamflow. The higher withdrawal rates (0.90 and 1.78 Mgal/d) would cause reach 3 to stop flowing about 10 to 20 percent of the time, but the effects of pumping rapidly diminished downstream because of tributary inflows. Simulation results indicate little change in the annual 1-, 7-, and 30-day low flows at the 0.20 Mgal/d pumping rate, but at the 1.78 Mgal/d pumping rate, reach 3 stopped flowing for nearly a 7-day period every year and for a 30-day period about every other year. At the 0.90 Mgal/d pumping rate, reach 3 stopped flowing about every other year for a 7-day period and about once every 5 years for a 30-day period. Land-use change was simulated by converting model hydrologic-response units (HRUs) representing undeveloped areas to HRUs representing developed areas on the basis of development suitability and town zoning. About 55 percent of the basin is suitable for development; this area would accommodate about 4,300 new low-density residential homes under current zoning. Increases in storm volume and peak flows, and decreases in base flow, typically associated with urbanization, were not evident in buildout simulations because the effective impervious area was assumed to increase by only 2 percent. Under fully developed conditions, withdrawals from self-supply wells were estimated to reach 1.2 Mgal/d. Potential increases in water withdrawals for a fully developed basin have only a minor impact on the main stem streamflow, but the effects of urbanization could be more pronounced in localized areas where development is concentrated. Streamflow-depletion rates were calculated for varying distances of a pumped irrigation well from a stream. For the irrigation rates and aquifer conditions tested, streamflow depletion, relative to the pumping rate, decreases rapidly as the pumped well was moved away from the stream. Streamflow depletion, relative to the peak withdrawal rate, decreased by about 60, 80, and 90 percent by locating the pumped well 500, 1,000, and 1,500 feet from the stream, respectively.

Rhode Island↗
USGS2003

Assessment of habitat and streamflow requirements for habitat protection, Usquepaug–Queen River, Rhode Island, 1999–2000

The relations among stream habitat and hydrologic conditions were investigated in the Usquepaug–Queen River Basin in southern Rhode Island. Habitats were assessed at 13 sites on the mainstem and tributaries from July 1999 to September 2000. Channel types are predominantly low-gradient glides, pools, and runs that have a sand and gravel streambed and a forest or shrub riparian zone. Along the stream margins, overhanging brush, undercut banks supported by roots, and downed trees create cover; within the channel, submerged aquatic vegetation and woody debris create cover. These habitat features decrease in quality and availability with declining streamflows, and features along stream margins generally become unavailable once streamflows drop to the point at which water recedes from the stream banks. Riffles are less common, but were identified as critical habitat areas because they are among the first to exhibit habitat losses or become unavailable during low-flow periods. Stream-temperature data were collected at eight sites during summer 2000 to indicate the suitability of those reaches for cold-water fish communities. Data indicate stream temperatures provide suitable habitat for cold-water species in the Fisherville and Locke Brook tributaries and in the mainstem Queen River downstream of the confluence with Fisherville Brook. Stream temperatures in the Usquepaug River downstream from Glen Rock Reservoir are about 6°F warmer than in the Queen River upstream from the impoundment. These warmer temperatures may make habitat in the Usquepaug River marginal for cold-water species. Fish-community composition was determined from samples collected at seven sites on tributaries and at three sites on the mainstem Usquepaug–Queen River. Classification of the fish into habitat-use groups and comparison to target fish communities developed for the Quinebaug and Ipswich Rivers indicated that the sampled reaches of the Usquepaug–Queen River contained most of the riverine fish species that would have been expected to occur in this area. Streamflow records from the gaging station Usquepaug River near Usquepaug were used to (1) determine streamflow requirements for habitat protection by use of the Tennant method, and (2) define a flow regime that mimics the river's natural flow regime by use of the Range of Variability Approach. The Tennant streamflow requirement, defined as 30 percent of the mean annual flow, was 0.64 cubic feet per second per square mile (ft 3 /s/mi 2 ). This requirement should be considered an initial estimate because flows measured at the Usquepaug River gaging station are reduced by water withdrawals upstream from the gage. The streamflow requirements may need to be revised once a watershed-scale precipitationrunoff model of the Usquepaug River is complete and a simulation of streamflows without water withdrawals has been determined.

Rhode Island↗
USGS2002

Quantifying vegetation and nekton response to tidal restoration of a New England salt marsh

Tidal flow to salt marshes throughout the northeastern United States is often restricted by roads, dikes, impoundments, and inadequately sized culverts or bridge openings, resulting in altered ecological structure and function. In this study we evaluated the response of vegetation and nekton (fishes and decapod crustaceans) to restoration of full tidal flow to a portion of the Sachuest Point salt marsh, Middletown, Rhode Island. A before, after, control, impact study design was used, including evaluations of the tide-restricted marsh, the same marsh after reintroduction of tidal flow (i.e., tide-restored marsh), and an unrestricted control marsh. Before tidal restoration vegetation of the 3.7-ha tide-restricted marsh was dominated by Phragmites australis and was significantly different from the adjacent 6.3-ha Spartina -dominated unrestricted control marsh (analysis of similarities randomization test, p < 0.001). After one growing season vegetation of the tide-restored marsh had changed from its pre-restoration condition (analysis of similarities randomization test, p < 0.005). Although not similar to the unrestricted control marsh, Spartina patens and S. alterniflora abundance increased and abundance and height of Phragmites significantly declined, suggesting a convergence toward typical New England salt marsh vegetation. Before restoration shallow water habitat (creeks and pools) of the unrestricted control marsh supported a greater density of nekton compared with the tide-restricted marsh (analysis of variance, p < 0.001), but after one season of restored tidal flow nekton density was equivalent. A similar trend was documented for nekton species richness. Nekton density and species richness from marsh surface samples were similar between the tide-restored marsh and unrestricted control marsh. Fundulus heteroclitus and Palaemonetes pugio were the numerically dominant fish and decapod species in all sampled habitats. This study provides an example of a quantitative approach for assessing the response of vegetation and nekton to tidal restoration.

Rhode Island↗
USGS2002

Glacial geology and aquifer characteristics of the Big River area, central Rhode Island

The Rhode Island Water Resources Board (RIWRB), which is responsible for developing the State's major water resources, is concerned that continued growth in demand for water in Rhode Island will severely stress water supplies. In the early 1960s, the State proposed construction of a surface-water reservoir in the Big River Basin in central Rhode Island to meet the growing water demands, but, to date (2001) the U.S. Environmental Protection Agency has not given approval for construction of this reservoir. As an alternative, the RIWRB would like to identify sites in the Big River area stream-aquifer system where high-yield supply wells can be constructed to meet future water demands. A cooperative study was initiated during the summer of 1995 by the U.S. Geological Survey (USGS) and the RIWRB to evaluate ground water as a source of water supply in the Big River area. This report presents the initial results of a multi-year investigation of the three-dimensional characteristics of the surficial aquifer system based on geologic and geophysical field studies, and provides information needed to protect, develop, and manage the Big River area stream-aquifer system. The Big River area includes the entire Big River drainage basin and part of the Mishnock River drainage basin (fig. 1) and covers approximately 35 mi2, including parts of the towns of Coventry, Exeter, and West Greenwich. Most of the Big River area is in Kent County, with a small part in Washington County; it encompasses parts of the Coventry Center, Hope Valley, Crompton, and Slocum 7.5-minute quadrangles. This investigation includes a characterization of the geologic framework and an evaluation of the hydraulic properties of the stream-aquifer system. The Big River area stream-aquifer system is the surficial aquifer and the network of rivers, brooks, lakes, and ponds that overlie and are in hydraulic connection with the aquifer. The surficial materials units of the Big River area and the accompanying bedrock-surface contours (pl. 1) were delineated on the basis of data collected during field mapping, seismic-refraction surveys, ground-penetrating radar surveys, logs from all available wells and test holes, and results of previous investigations. Some streams in the study area lose surface water naturally to the underlying sand and gravel aquifer, whereas others lose water to the aquifer by induced infiltration of streamflow caused by ground-water withdrawals. Most large ground-water withdrawals are from public-supply wells in the sand and gravel aquifer in the Mishnock River Basin. Minimal ground-water withdrawals take place in the Big River Basin, because most of the land is designated as open space and protected from development by State law. The primary use of surface water in the study area is for recreation. Water from the Flat River Reservoir, the largest surface-water body in the study area, is used only for recreational purposes.

Rhode Island↗
USGS2002

Sources of sodium and chloride in the Scituate Reservoir drainage basin, Rhode Island

The Scituate Reservoir system is the principal drinking-water supply for more than 60 percent of the population of Rhode Island. Sodium concentrations in the reservoir have been increasing slowly in recent years despite the long-term (12 years) use of a reduced-sodium deicing agent on State-maintained highways in the reservoir drainage basin. This report identifies the major sources of sodium and chloride in the drainage basin, and assesses the relative contribution of each source to the total amounts of these constituents that entered the basin from October 1999 through September 2000 (Water Year 2000).

Rhode Island↗
USGS2001

Hydrogeologic data for the Big River–Mishnock River stream-aquifer system, central Rhode Island

Hydrogeology, ground-water development alternatives, and water quality in the Big­Mishnock stream-aquifer system in central Rhode Island are being investigated as part of a long-term cooperative program between the Rhode Island Water Resources Board and the U.S. Geological Survey to evaluate the ground-water resources throughout Rhode Island. The study area includes the Big River drainage basin and that portion of the Mishnock River drainage basin upstream from the Mishnock River at State Route 3. This report presents geologic data and hydrologic and water-quality data for ground and surface water. Ground-water data were collected from July 1996 through September 1998 from a network of observation wells consisting of existing wells and wells installed for this study, which provided a broad distribution of data-collection sites throughout the study area. Streambed piezometers were used to obtain differences in head data between surface-water levels and ground-water levels to help evaluate stream-aquifer interactions throughout the study area. The types of data presented include monthly ground-water levels, average daily ground-water withdrawals, drawdown data from aquifer tests, and water-quality data. Historical water-level data from other wells within the study area also are presented in this report. Surface-water data were obtained from a network consisting of surface-water impoundments, such as ponds and reservoirs, existing and newly established partial-record stream-discharge sites, and synoptic surface-water-quality sites. Water levels were collected monthly from the surface-water impoundments. Stream-discharge measurements were made at partial-record sites to provide measurements of inflow, outflow, and internal flow throughout the study area. Specific conductance was measured monthly at partial-record sites during the study, and also during the fall and spring of 1997 and 1998 at 41 synoptic sites throughout the study area. General geologic data, such as estimates of depth to bedrock and depth to water table, as well as indications of underlying geologic structure, were obtained from geophysical surveys. Site-specific geologic data were collected during the drilling of observation wells and test holes. These data include depth to bedrock or refusal, depth to water table, and lithologic information.

Rhode Island↗
USGS2001

Numerical-simulation and conjunctive-management models of the Hunt-Annaquatucket-Pettaquamscutt stream-aquifer system, Rhode Island

Numerical-simulation and optimization techniques were used to evaluate alternatives for the conjunctive management of ground- and surface-water resources of the Hunt­-Annaquatucket­-Pettaquamscutt stream-aquifer system in central Rhode Island. Ground-water withdrawals from the Hunt-Annaquatucket-Pettaquamscutt aquifer exceeded 8 million gallons per day during months of peak water use during 1993­98, and additional withdrawals have been proposed to meet growing demands from within and outside of the system boundary. The system is defined by the Hunt­-Annaquatucket­-Pettaquamscutt aquifer, which is composed of glacial stratified deposits, and the network of rivers, brooks, and ponds that overlie and are in hydraulic connection with the aquifer. Nearly all of the water withdrawn, however, is derived from depletions of flow in the rivers, brooks, and ponds that overlie the aquifer. Streamflow depletions are of concern to environmental agencies because of the adverse effects that reductions in streamflow can have on aquatic and riparian ecosystems. A conjunctive-management model of the stream-aquifer system was developed to simultaneously address the water-demand and streamflow-depletion issues. The objective of the model was to maximize total ground-water withdrawal from the aquifer during July, August, and September. These three months are generally the time of year when water-supply demands are largest and streamflows are simultaneously lowest. Total withdrawal from the aquifer was limited by a set of constraints specified in the model. These constraints were (1) maximum rates of streamflow depletion in the Hunt, Annaquatucket, and Pettaquamscutt Rivers; (2) minimum monthly water demands of each of three water-supply systems that withdraw water from the aquifer; and (3) minimum and maximum withdrawal rates at each supply well. The conjunctive-management model was formulated mathematically as a linear program. The model was solved by a response-matrix technique that incorporates the results of transient, numerical simulation of the stream-aquifer system into the constraint set of the linear program. The basis of the technique was the assumption that streamflow-depletion rates in each river were a linear function of ground-water-withdrawal rates at each well. This assumption was shown to be valid for the conditions evaluated in this study, primarily because of the very high transmissivity of the aquifer near many of the wells pumped for water supply. A transient, numerical model of the system was developed to simulate an average annual cycle of monthly withdrawal and hydrologic conditions representative of the 56-year period 1941­96. The transient model was used to generate characteristic streamflow-depletion responses in each river to simulated withdrawals at each well; these characteristic responses, or response coefficients, were then incorporated directly into the streamflow-depletion constraints of the linear program. Four sets of applications of the conjunctive-management model were made to determine whether total ground-water withdrawal from the aquifer during July, August, and September could be increased over the current total withdrawal for alternative definitions of the maximum rates of streamflow depletion allowed in the Hunt, Annaquatucket, and Pettaquamscutt Rivers. Current conditions were defined as the average monthly withdrawal rates at each supply well, water demands of each of the three water-supply systems, and estimated streamflow-depletion rates during the 6-year period 1993­98. Total withdrawal from all wells in the system from July through September during 1993­98 was 506.5 million gallons. Estimated streamflow-depletion rates for 1993­98 were calculated by use of the transient model, with the 1993­98 average monthly withdrawal rates specified at each supply well. Streamflow-depletion rates calculated for July, August, and September averaged 25 percent of the model-calculated pre-withdrawal streamflow rates for the Hunt River, 19 percent for the Annaquatucket River, and 7 percent for the Pettaquamscutt River. The first set of applications of the model were made with the current estimated rates of streamflow depletion in the Hunt, Annaquatucket, and Pettaquamscutt Rivers. Results of these applications indicated that total withdrawal from the aquifer during July, August, and September could be increased from about 8 to 18 percent (from 546.0 to 596.3 million gallons) over the current total withdrawal. The increased withdrawal would require modifications to the current annual withdrawal schedule of each supply well and, for the 18-percent increase, a modified network of supply wells that would include two new wells in the Annaquatucket River Basin. A second set of model applications then was made to determine if current estimated rates of streamflow depletion in the Hunt River could be reduced without increasing current estimated rates of streamflow depletion in the Annaquatucket or Pettaquamscutt Rivers. Decreases in the current rates of streamflow depletion in the Hunt River would result in increased streamflow in the river during these three months. Results showed that current rates of streamflow depletion in the Hunt River during July, August, and September could be decreased from 5 to 15 percent, depending on whether the existing or modified well network was used. Subsequent model applications indicated that substantial increases in total ground-water withdrawal from the aquifer are possible, but would require increased rates of streamflow depletion in the Annaquatucket and Pettaquamscutt Rivers. Maximum increases in the July through September withdrawal from the aquifer of about 39 to 50 percent (from 705.1 to 760.3 million gallons) over the current total withdrawal were calculated when streamflow-depletion rates in the Annaquatucket and Pettaquamscutt Rivers were allowed to increase from current estimated rates to a maximum of 25 percent of the model-calculated pre-withdrawal streamflow for each river during July, August, and September. Alternatively, it was shown that current estimated rates of streamflow depletion in the Hunt River during July, August, and September could be reduced by as much as 35 percent for the maximum allowed increases in streamflow depletion in the Annaquatucket and Pettaquamscutt Rivers; maximum increased withdrawal from the aquifer, however, would range from 8 to 18 percent over the current total withdrawal for the 35-percent reduction in streamflow-depletion rates in the Hunt River. Results of the different applications of the model demonstrate the usefulness of coupling numerical-simulation and optimization techniques for regional-scale evaluation of water-resource management alternatives. The results of the evaluation must be viewed, however, within the limitations of the quality of data available for the Hunt­-Annaquatucket­-Pettaquamscutt stream-aquifer system and representation of the system by a simulation model. An additional limitation of the analysis was the use of an average annual cycle of monthly withdrawal and hydrologic conditions. Ground-water withdrawal strategies may need to be modified to meet streamflow-depletion constraints during extreme hydrologic events, such as droughts. Contributing areas and sources of water to the supply wells also were delineated by use of a steady-state model of the stream-aquifer system. The model was developed to simulate long-term-average ground-water flow and ground-water/ surface-water interactions in the system during the 56-year period 1941­96. Sources of water to the wells consisted of precipitation and wastewater recharge to the aquifer, streamflow leakage from natural stream-channel losses, streamflow leakage caused by induced infiltration, and lateral ground-water inflow from till and bedrock upland areas.

Rhode Island↗
USGS2000

Distribution of selected volatile organic compounds determined with water-to-vapor diffusion samplers at the interface between ground water and surface water, Centredale Manor site, North Providence, Rhode Island, September 1999

Volatile organic compounds are present in soils and ground water at the Centredale Manor Superfund Site in North Providence, Rhode Island. In September 1999, water-to-vapor diffusion samplers were placed in the bottom sediments of waterways adjacent to the site to identify possible contaminated ground-water discharge areas. The approximate12-acre site is a narrow stretch of land between the eastern bank of the Woonasquatucket River, downstream from the U.S. Route 44 bridge and a former mill raceway. The samplers were placed along a 2,250-foot reach of the Woonasquatucket River, in the former mill raceway several hundred feet to the east and parallel to the river, and in a cross channel between the river and former mill raceway. Volatile organic compounds were detected in 84 of the 104 water-to-vapor diffusion samplers retrieved. Trichloroethylene and tetrachloro-ethylene were the principal volatile organic compounds detected. The highest vapor concentrations measured for these two chemicals were from diffusion samplers located along an approximate 100-foot reach of the Woonasquatucket River about 500 feet downstream of the bridge; here trichloroethylene and tetrachloroethylene vapor concentrations ranged from about 2,000 to 180,000 and 1,600 to 1,400,000 parts per billion by volume, respectively. Upstream and downstream from this reach and along the former mill raceway, trichloroethylene and tetrachloroethylene vapor concentrations from the diffusion samples were generally less than 100 parts per billion by volume. Along the lower reaches of the river and mill raceway, however, and in the cross channel, vapor concentrations of trichloroethylene exceeded 100 parts per billion by volume and tetrachloroethylene exceeded 1,000 parts per billion by volume in several diffusion samples. Although diffusion sample vapor concentrations are higher than water concentrations in surface waters and in ground water, and they should only be interpreted qualitatively as relative values, these values provide important information as to potential discharge areas of contaminants.

Rhode Island↗
USGS2000

Water-quality conditions and relation to drainage-basin characteristics in the Scituate Reservoir Basin, Rhode Island, 1982-95

The Scituate Reservoir Basin covers about 94 square miles in north central Rhode Island and supplies more than 60 percent of the State of Rhode Island's drinking water. The basin includes the Scituate Reservoir Basin and six smaller tributary reservoirs with a combined capacity of about 40 billion gallons. Most of the basin is forested and undeveloped. However, because of its proximity to the Providence, Rhode Island, metropolitan area, the basin is subject to increasing development pressure and there is concern that this may lead to the degradation of the water supply. Selected water-quality constituent concentrations, loads, and trends in the Scituate Reservoir Basin, Rhode Island, were investigated locate parts of the basin likely responsible for exporting disproportionately large amounts of water-quality constituents to streams, rivers, and tributary reservoirs, and to determine whether water quality in the basin has been changing with time. Water-quality data collected between 1982 and 1995 by the Providence Water Supply Board PWSB) in 34 subbasins of the Scituate Reservoir Basin were analyzed. Subbasin loads and yields of total coliform bacteria, chloride, nitrate, iron, and manganese, estimated from constituent concentrations and estimated mean daily discharge records for the 1995 water year, were used to determine which subbasins contributed disproportionately large amounts of these constituents. Measurements of pH, color, turbidity, and concentrations of total coliform bacteria, sodium, alkalinity, chloride, nitrate, orthophosphate, iron, and manganese made between 1982 and 1995 by the PWSB were evaluated for trends. To determine the potential effects of human-induced changes in drainage- basin characteristics on water quality in the basin, relations between drainage-basin characteristics and concentrations of selected water-quality constituents also were investigated. Median values for pH, turbidity, total coliform bacteria, sodium, alkalinity, chloride, nitrate, and iron were largest in subbasins with predominately residential land use. Median instantaneous loads reflected drainage-basin size. However, loads normalized by drainage area (median instantaneous yields) also were largest in residential areas where point and non-point sources are likely, and in areas of poorly drained soils. Significant trends in water-quality constituents from 1982 to 1995 in the Scituate Reservoir Basin indicate that the quality of the water resources in the basin may be slowly changing. Scituate Reservoir subbasins with large amounts of residential land use showed increasing trends in alkalinity and chloride. In contrast, subbasins distributed throughout the drainage basin showed increasing trends in pH, color, nitrate, and iron concentrations, indicating that these characteristics and constituents may be affected more by atmospheric deposition. Although changing, water-quality constituent concentrations in the Scituate Reservoir Basin only occasionally exceeded Rhode Island and USEPA water-quality guidelines and standards. Result of correlation analysis between pH, color, turbidity, and concentrations total coliform bacteria, sodium, alkalinity, chloride, nitrate, orthophosphate, iron, and manganese and land use, geology, wetlands, slope, soil drainability, and roads indicated that the percentage of wetlands, roads, and slope appear have the greatest effect on water-quality in the Scituate Reservoir Basin. The percentage of urban, residential, and commercial land use also are important, but to a lesser degree than wetlands, roads, and slope. Finally, geology appears to have the least effect on water quality compared to other drainage-basin characteristics investigated.

Rhode Island↗
USGS1999

Volatile organic compounds detected in vapor-diffusion samplers placed in sediments along and near the shoreline at Allen Harbor Landfill and Calf Pasture Point, Davisville, Rhode Island, March-April 1998

Volatile organic compounds are present in ground water at the Allen Harbor Landfill and the Calf Pasture Point sites on the former Naval Construction Battalion Center in Davisville, R.I. Vapor-diffusion samplers were used at the two sites during March-April 1998 to identify possible discharge points for contaminants along the shore of Allen Harbor and in two wetland areas near the shore. Results from vapor-diffusion samplers will be used in conjunction with other site information to evaluate proposed ground-water monitoring programs. Volatile organic compounds were detected in 41 of 115 samplers placed along the shoreline at the Allen Harbor Landfill. Trichloroethylene was the principal volatile organic compound detected of eight target compounds. The highest vapor concentration measured exceeded 300,000 parts per billion by volume in an area where TCE was detected in groundwater from nearby monitoring wells. Other chemicals detected in vapor-diffusion samplers included tetrachloroethylene, toluene, and benzene. Concentrations of individual volatile organic compounds were less than 100 parts per billion by volume in most samplers. Volatile organic compounds, principally trichloroethylene, were detected in 7 of 30 samplers placed along the shoreline at Calf Pasture Point; the highest trichloroethylene concentration was 1,900 parts per billion by volume. A trace concentration of tetrachloroethylene was detected in one of the samplers. One of 24 samplers placed in two wetland areas near the shore (suspected discharge areas for ground-water containing volatile organic compounds) detected trichloroethylene at a vapor concentration of 14 parts per billion by volume.

Rhode Island↗
USGS1999

Distribution of salinity in ground water from the interpretation of borehole-geophysical logs and salinity data, Calf Pasture Point, Davisville, Rhode Island

The distribution of salinity in ground water at Calf Pasture Point, a small coastal peninsula bounded by Narragansett Bay on the east and Allen Harbor on the west, in Davisville, Rhode Island, was interpreted from borehole-geophysical data and previously collected salinity data to help identify potential flowpaths of contaminated ground water to surface-water bodies. The surficial material at this 40-acre site, which ranges in thickness from about 30 to 85 feet, is composed of an upper sand unit, a silt unit, and a till unit overlying bedrock. Borehole-geophysical data indicate that fresh ground water is present in all surficial units in the northern and northwestern part of the site. In the central and eastern parts of the site, where most of the current land surface is composed of dredged fill placed in a small saltwater embayment, brackish and saline ground water predominate. Fresh ground water moving into this area from upgradient and recharge to this extended land surface from precipitation is diluting the saline groundwater in the upper sand and till units, and to a lesser extent in the silt unit. In this area, the freshwater-flow system is slowly expanding towards Narragansett Bay and the entrance channel to Allen Harbor.

Rhode Island↗
USGS1997

Ground-water flow and contaminant transport at a radioactive-materials processing site, Wood River Junction, Rhode Island

Liquid wastes from an enriched-uranium cold-scrap recovery plant at Wood River Junction, Rhode Island, were discharged to the environment through evaporation ponds and trenches from 1966 through 1980. Leakage from the ponds and trenches resulted in a plume of contaminated ground water extending northwestward to the Pawcatuck River through a highly permeable sand and gravel aquifer of glacial origin.

Rhode Island↗
USGS1997

Hydrogeology, water quality, and simulation of ground-water-development alternatives in the Usquepaug-Queen ground-water reservoir, southern Rhode Island

The Usquepaug-Queen River Basin study describes the hydrogeology, water quality, and simulation of pumping from wells for selected ground-water-development alternatives in the ground-water reservoir under average (1975-90) and drought (1963-66) conditions. In general, ground-water quality is suitable for most purposes. The study provides an evaluation of the effects of simulated pumping of 4 to 11 million gallons per day of ground water on the stream-wetland-aquifer system. Three principal geologic units underlie the Usquepaug-Queen River Basin glacial stratified deposits (stratified drift), glacial till, and crystalline bedrock. Thick and extensive deposits of saturated coarse-grained stratified deposits form the major and most productive aquifer in the Usquepaug-Queen River Basin. The 36.1-square mile Usquepaug-Queen River Basin is in the Pawcatuck River Basin in southern Rhode Island. Stratified deposits cover about 42 percent of the basin and reach a maximum known thickness of 122 feet. The stratified deposits are subdivided into coarse-grained units (dominantly fine to very coarse sand and gravel) and fine-grained units (dominantly very fine sand, silt, and clay). Transmissivity is highest in coarse-grained stratified materials, which have the capability of yielding relatively high volumes of water to wells. Transmissivity is lowest in fine-grained stratified materials, which consist predominantly of lakebottom deposits. Transmissivity of the stratified drift aquifer ranges from 1,900 to 27,800 feet squared per day, and horizontal hydraulic conductivity ranges from 25 to 470 feet per day. The stratified-drift aquifer is the only aquifer in the Usquepaug-Queen River Basin capable of producing yields of 0.5 million gallons per day or more from individual wells. Pumping from ground-water and surface-water sources in the Usquepaug-Queen River Basin averaged 0.28 million gallons per day during 1989 and 0.48 million gallons per day during 1990. Ground water and surface water (which is primarily ground-water runoff) in the UsquepaugQueen River Basin are suitable for most purposes on the basis of a comparison of physical properties and chemical constituents to drinking-water standards. Ground water in the basin is somewhat corrosive because of its low hydrogen-ion concentration. Specific conductance and concentrations of dissolved chloride and dissolved sodium are high in ground water in parts of the Usquepaug-Queen River Basin, which indicates the effects of highway de-icing salts on groundwater quality. Nitrogen (nitrite plus nitrate) concentrations in some localized areas exceed the U.S. Environmental Protection Agency maximum contaminant level of 10 milligrams per liter for drinking water. The effects of selected ground-waterdevelopment alternatives on ground-water levels, wetland-water levels, and streamflow in the Usquepaug-Queen ground-water reservoir were evaluated by means of a three-layer ground-waterflow model. Development alternatives were simulated for average annual (1975-90) and drought (1963-66) conditions. In general, higher simulated pumping rates produced greater drawdowns than lower pumping rates. Drawdowns generally can be reduced by distributing the total pumping over many wells; however, drawdowns were minimal (less than 1.3 feet) in well SNW 906, which was near a major stream (recharge boundary); and drawdowns were substantial (at least 12 feet) in well EXW 33, which was near the edge of the model aquifer boundary (barrier boundary). Total gains in flow from ground-water discharge for all streams in the model area were not affected by the location of wells; however, the amount of ground-water pumpage derived from induced infiltration of streamflow varies significantly. Water levels in the wetlands tend to be constant even during simulated pumping. In general, pumping during simulated drought conditions increased drawdowns fractionally and greatly reduced overall streamflow gains. Pumping from the Usquepaug-Queen stratified-drift aquifer causes infiltration of streamflow along stream segments simulated in the ground-water-flow model. Results of simulations for average conditions show that from 56 to 75 percent of the total water pumped is derived from intercepted ground-water runoff and that the amount of well water derived from induced recharge of streamflow ranged from 20 to 39 percent. The areal extent of contributing areas for selected simulated pumping wells suggest that large areas of stratified drift may need to be protected from land-use practices that are incompatible with the development of potable ground water in the Usquepaug-Queen ground-water reservoir.

Rhode Island↗
USGS1995

Sources of geologic and hydrologic information pertinent to ground-water resources in Rhode Island

This report summarizes sources of geologic and hydrologic information useful to water managers and others involved in the investigation, appraisal, development, and protection of ground-water resources in Rhode Island. The geographic scope of the report includes Rhode Island and small adjoining areas of Massachusetts and Connecticut, where drainage basins are shared with these States. The information summarized is found in maps and reports prepared by the U.S. Geological Survey and published by either the U.S. Geological Survey or by the State of Rhode Island. Information sources are presented in maps and tables. Reference maps show drainage divides, town lines, and the 7.5-minute grid of latitude and longitude for the State. Maps show availability of surficial geologic maps, bedrock geologic maps, and ground-water studies by 7.5-minute quadrangle, and show availability of ground-water studies by drainage basin, subbasin, and special study area. Sources of geologic and hydrologic information for the thirty-seven 7.5-minute quadrangles covering Rhode Island have been compiled based on the following information categories: surficial geology, bedrock geology, subsurface materials, altitude of bedrock surface, water-table altitudes, water-table contours, saturated thickness, hydraulic conductivity, transmissivity, drainage divides, recharge areas, ground-water reservoirs, induced infiltration, and ground-water quality. A table for each of the 37 quadrangles lists the major categories of information available for that quadrangle, provides references to the publications in which the information can be found, and indicates the format, scale, and other pertinent attributes of the information. A table organized by report series gives full citations for publications prepared by the U.S. Geological Survey pertaining to the geology and hydrology of Rhode Island. To facilitate location of information for particular municipalities, a table lists cities and towns in the State and the quadrangles that cover each municipality.

Rhode Island↗