Vermont Geological Survey Open File Report VG09-8, Plate 6 of 7 73°0'0"W 72°0'0"W 45°0'0"N

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' ' NORTON 0 FRANKLIN 0 CANAAN " " HIGHGATE W RICHFORD JAY HOLW LAND ALBURGH AVERILL TROY NEWPORT TOWN NEWPORT CITY WARNERS GRANT WARREN GOREAVERYS GORE SWANTON SHELDON MORGAN LEMINGTON ENOSBURG WESTFIELD LEWIS ISLE LA MOTTE FRANKLIN MONTGOMERY COUNTY CHARLESTON NORTH HERO ORLEANS BROWNINGTON COUNTY IRASBURG BLOOMFIELD ST. ALBANS TOWNST. ALBANS CITY FAIRFIELD GRAND ISLE BRIGHTON COUNTY BAKERSFIELD LOWELL

BELVIDERE BARTON WESTMORE

BRUNSWICK GEORGIA ALBANY FERDINAND GRAND ISLE WATERVILLE FLETCHER EDEN ESSEX NEWARK COUNTY FAIRFAX GLOVER

SUTTON CRAFTSBURY EAST HAVEN MILTON JOHNSON MAIDSTONE SOUTH HERO HYDE PARK . LAMOILLE BURKE WESTFORD COUNTY GREENSBORO GRANBY

WOLCOTT WHEELOCK COLCHESTER GUILDHALL MORRISTOWN LYNDON VICTORY Legend UNDERHILL STANNARD ESSEX HARDWICK Areas of lower and higher yield based on an inverse distance weighted analysis of 92315 well points. WINOOSKI KIRBY BURLINGTON ELMORE JERICHO STOWE WALDEN LUNENBURG 0 - 1 CHITTENDEN CALEDONIA COUNTY COUNTY ST. JOHNSBURY 1.1 - 2 WOODBURY SOUTH BURLINGTONWILLISTON DANVILLE CONCORD 2.1 - 40; no color WORCESTER BOLTON CABOT 40.1 - 300 SHELBURNE RICHMOND WATERBURY ST. GEORGE WATERFORD 300.1 - 933.9 CALAIS

Mean yield of wells by bedrock unit (see Plate 4) PEACHAM HINESBURG MIDDLESEX 72°0'0"W CHARLOTTE MARSHFIELD BARNET 2 - 4.99 gpm HUNTINGTON DUXBURY EAST MONTPELIER WASHINGTON COUNTY 5 - 9.99 gpm MONTPELIER MORETOWN PLAINFIELD 10 - 14.99 gpm GROTON MONKTON STARKSBORO RYEGATE FAYSTON 15 - 19.00 gpm FERRISBURG BUELS GORE BERLIN BARRE CITY WAITSFIELD 20 - 34.57 gpm VERGENNES BARRE TOWN ORANGE NORTHFIELD VT State Boundary PANTON WALTHAM TOPSHAM VT County Boundary NEW HAVEN WARREN WILLIAMSTOWN NEWBURY LINCOLN VT Town Boundary

ADDISON ROXBURY WASHINGTON Lake ADDISON COUNTY WEYBRIDGE CORINTH BROOKFIELD ORANGE COUNTY BRADFORD 44°0'0"N MIDDLEBURY GRANVILLE 7

3 44°0'0"N CHELSEA 44°0'0"N

RIP° TON

BRIDPORT 0 ' 0 " W BRAINTREE CORNWALL VERSHIRE WEST FAIRLEE RANDOLPH EXPLANATION FAIRLEE SALISBURY HANCOCK The Inverse Distance Weighted (IDW) analysis is a raster analysis used to summarize values on the map. The analysis shows areas of possible higher and lower yield based on existing data points. "Inverse distance weighted (IDW) SHOREHAM TUNBRIDGE interpolation determines cell values using a linearly weighted combination of a set of sample points. The weight is a function of inverse distance. The surface being interpolated should be that of a locationally dependent ROCHESTER variable." (from ESRI ArcMap) STRAFFORD WHITING GOSHEN The IDW raster analysis used in this study was set to consider the closest 6 points. The digital data and original data BETHEL (well data, bedrock map, surficial map) are at various scales and quality and the results of the raster analysis are THETFORD a rough approximation only. The raster analysis does not attempt to provide a probabilistic analysis and it is only a presentation of clusters of values. These clusters will change with the addition of more data points. ROYALTON ORWELL BRANDON PITTSFIELD The raster statistics summarize attribute values of the well points and assigns a value to each cell in the layer. SUDBURY Of the 92513 wells statewide, only 12% have locations verified by E911 address or by a GPS location. SHARON There are also numerical errors in the database and not all of the errors have been corrected. The yield values may be inflated due to difficulty measuring high yield wells in the field. The IDW analysis is not probabilistic and is not CHITTENDEN STOCKBRIDGE intended to be used as a predicting tool. Moore et. al., 2002*, published “Factors Related to Well Yield in the Fractured-Bedrock Aquifer of the New ” in BARNARD which they discussed a number of factors correlated positively or negatively to well yield. Among these factors are year BENSON HUBBARDTON PITTSFORD drilled, median household income, drilling method, up gradient drainage area, thickness of overburden, depth drilled, proximity to streams/water bodies, type of bedrock, steepness of slope, elevation, fractures, and POMFRET geologic structures.

*Moore, R.B., Schwarz, G.E., Clark, S.F., Jr., Walsh, G.J., and Degnan, J. R., 2002, Factors related to well yield in HARTFORD the fractured-bedrock aquifer of New Hampshire: USGS Professional Paper 1660. PROCTOR KILLINGTON WEST HAVEN CASTLETON RUTLAND MENDON BRIDGEWATER FAIR HAVEN WEST RUTLAND RUTLAND CITY WOODSTOCK RUTLAND COUNTY HARTLAND DATA AND DATA SOURCES: Number of wells: 92,315 IRA WINDSOR COUNTY Number of located wells: 10,807 Mean yield, all wells: 13.76 gpm POULTNEY CLARENDON SHREWSBURY Median yield, all wells: 6 gpm Mean depth, all wells: 293.02 ft. Median depth, all wells: 260 ft. READING MIDDLETOWN SPRINGS WEST WINDSOR The well data used in this study is a derivative set of the WINDSOR Vermont Dept. of Environmental Conservation Water Supply Division (WSD) well driller database. The location of the data points is from 1) well driller maps and TINMOUTH WALLINGFORD written descriptions, 2) E911 addresses (3100 wells), and WELLS MOUNT HOLLY 3) GPS measurements (7707 wells). Only 12% of the wells have a reliable location. CAVENDISH Of the 92,315 wells, most are completed in bedrock, LUDLOW although many have no entry in the "well type" WEATHERSFIELD data field. Some corrections were made to the database where numerical errors were PAWLET obvious and could be reconciled with a driller report. DANBY BALTIMORE MOUNT TABOR No attempt was made to discern the rock type in which a well was actually completed as compared to the rock type at the surface. Where units are thin and shallow dipping, it WESTON is possible that a well penetrates one or more formations. Point density is shown in shades of blue, with deeper shades reflecting higher point density. SPRINGFIELD LANDGROVE ANDOVER Bedrock map units from the USGS digital data from the RUPERT 1961 Centennial Geologic Map of Vermont, scale 1:250,000. PERU Reference: USGS Open-File Report 2006-1272 Preliminary Integrated Geologic Map Databases for the United States: Connecticut, Maine, Massachusetts, New Hampshire, New Jersey, Rhode Island and Vermont LONDONDERRY http://pubs.usgs.gov/of/2006/1272/ GRAFTON ROCKINGHAM SANDGATE WINDHAM WINHALL THIS MAP IS A SUMMARY OF WATER WELL DATA AND BEDROCK GEOLOGIC UNIT. THE MAP IS NOT PROBABALISTIC AND SHOULD NOT BE USED ALONE ATHENS TO PREDICT YIELD OR DEPTH. JAMAICA

ARLINGTON SUNDERLAND TOWNSHEND WESTMINSTER STRATTON

BENNINGTON COUNTY WARDSBORO BROOKLINE 43°0'0"N

7 WINDHAM WELL YIELD (GPM) SUMMARY OF 92,315 WATER WELLS 3 43°0'0"N PUTNEY 43°0'0"N °

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S" OMERSET W NEWFANE BY INVERSE DISTANCE WEIGHTED METHOD, VERMONT DOVER by Marjorie Gale, George Springston, Laurence Becker, and Ryan Knox DUMMERSTON 2009

SEARSBURG BENNINGTON WOODFORD WILMINGTON MARLBORO BRATTLEBORO

READSBORO POWNAL STAMFORD WHITINGHAM HALIFAX GUILFORD

VERNON Published by: VT Geological Survey, L. Becker, State Geologist 73°0'0"W VT Dept. of Environmental Conservation Miles VT Agency of Natural Resources 10 5 0 10 20 30 103 South Main St., Logue Cottage Waterbury, VT 05671-2420 http://www.anr.state.vt.us/dec/geo/vgs.htm 802.241.3608 SCALE 1:250,000