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A regional watershed model was developed for watersheds contributing to Long Island Sound, including the Connecticut River basin. The study region covers approximately 40 900 km 2 , extending from a moderate coastal climate zone in the south to a mountainous northern New England climate zone dominated by snowmelt in the north. The input data indicate that precipitation and temperature have been increasing for the last 46 years across the region. Minimum temperature has increased more than maximum temperature over the same period . The model simulation indicates that there was an upward trend in groundwater recharge across most of the modeled region. However, trends in increasing precipitation and groundwater recharge are not significant at the 0.05 level if the drought of 1961-67 is removed from the time series. The trend in simulated snowfall is not significant across much of the region, although there is a significant downward trend in southeast Connecticut and in central Massachusetts. To simulate future trends, two input datasets, one assuming high carbon emissions and one assuming low carbon emissions, were developed from GCM forecasts. Under both of the carbon emission scenarios, simulations indicate that historical trends will continue, with increases in groundwater recharge over much of the region and substantial snowfall decreases across Massachusetts, Connecticut, southern Vermont, and southern New Hampshire. The increases in groundwater recharge and decreases in snowfall are most pronounced for the high emission scenario.

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This fact sheet, the USGS national data and investigations reports, and other information are available on the World Wide Web at http://water.usgs.gov/nawqa/swqa. Included at this Web site are downloadable data on organic compound occurrence, information on sampling designs and methodology, background on data analyses, and frequently asked questions.

For more information on the USGS-the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment-visit http://www.usgs.gov/ or call 1-888-ASK-USGS.For an overview of USGS information products, including maps, imagery, and publications, visit http://www.usgs.gov/pubprod/.Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner.Suggested citation: Brown, C.J., Mullaney, J.R., Morrison, Jonathan, Martin, J.W., and Trombley, T.J., 2015, Chloride concentrations, loads, and yields in four watersheds along Interstate 95, southeastern Connecticut, 2008-11-Factors that affect peak chloride concentrations during winter storms: U.S. Geological Survey Scientific Investigations Report 2015-5057, 68 p., http://dx.doi.org/10.3133/sir20155057. ISSN 2328-0328 (online) iii AcknowledgmentsThe authors would like to thank Eloise Powell, Robert Turner, and Patricia Cazenas of the Federal Highway Administration; Paul Corrente, Kevin Carifa, and James Spencer of the Connecticut Department of Transportation; and the Connecticut Academy of Science and Engineering team for technical input and guidance and for providing data or information. In addition, the authors would like to thank U.S. Geological Survey employees Timothy Sargent, David Bjerklie, Daniel Lolos, Remo Mondazzi, and Timothy Frick for maintenance of streamgages and water-quality monitors, and collection of water-quality samples. Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as °F = (1.8 × °C) + 32. DatumVertical coordinate information is referenced to the North American Vertical Datum of 1988 (NAVD 88).Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).Altitude, as used in this report, refers to distance above the vertical datum. x Supplemental InformationSpecific conductance is given in microsiemens per centimeter at 25 degrees Celsius (µS/cm at 25 °C).Concentrations of chemical constituents in water are given in milligrams per liter (mg/L), unless otherwise noted. Chloride concentrations varied considerably in shallow Jordan Brook watersheds, where developed land ranged from groundwater as a result of land-use differences. Cl -concen-9 to 32 percent. Water-quality samples were collected and spe-trations were very high (as high as 800 mg/L) in shallow cific conductance was measured continuously at paired watergroundwater downstream from I-95 at the Four Mile River quality monitoring sites, upstream and downstream from I-95. site. Chloride/bromide mass concentration ratios and the Specific conductance values were related to Cl -concentrations proximity of a former landfill and sewage lagoon upstream to assist in determining the effects of road-deicin...