RELIABLE DROUGHT YIELDS OF PUBLIC SUPPLY WELLS IN THE FRACTURED ROCK AREAS OF CENTRAL MARYLAND
During the severe drought period of 1998-2002, many municipal water suppliers in the Piedmont/Blue Ridge (fractured rock) areas of central Maryland had to institute water restrictions related to declining well yields. The yields were typically about ½ of those estimated from initial aquifer/pumping tests upon completion of the wells. The methods developed in the present study improve the accuracy of estimates made for well yields and include techniques to determine seasonal variations in well yields to account for drought effects.

MAP OF HYDRAULIC DATA FOR FRACTURED ROCK SUPPLY WELLS IN CENTRAL MARYLAND
An interactive map that includes from the reliable yields report step and aquifer test data, diagnostic plots, well construction characteristics, and descriptive reports for selected supply wells.

HYDROLOGICAL IMPACTS CAUSED BY DEWATERING OF THE METTIKI D-MINE, GARRETT COUNTY, MARYLAND
This study describes the hydrologic impacts due to dewatering of the Mettiki Coal Corporation D-Mine in southwestern Garret County. 38 water supplies were replaced, and one spring box repaired, due to mine dewatering, while there were only three replacements drilled in the D-Mine area prior to its development. The average flows in McMillan Fork declined by about 20%, after being undermined by the D-Mine. Flows in the North Fork of Sand Run declined about 40% due to mine dewatering. Biological sampling indicated McMillan Fork was impaired, due to inadequate streamflow. The North Fork of Sand Run was impaired due to a small drainage area.

INTERFERENCE IMPACTS CAUSED BY GROUNDWATER WITHDRAWALS FROM PUBLIC SUPPLY WELLS IN THE CRYSTALLINE ROCK AQUIFERS OF CENTRAL MARYLAND
This study investigated the few crystalline rock aquifer impacts that have occurred in Maryland were due to withdrawals from Myersville (four domestic wells with declining yields) and Middletown public supply wells (one domestic well and a lawn irrigation well with declining yields, and two other domestic wells with high turbidity levels). Impacts (three domestic wells with declining yields) also occurred during aquifer testing at the Waterside community of a proposed public supply well that was never placed in service. A ¼ fracture length (¼ L) analytical model was developed from data collected during aquifer testing and monitoring at the Myersville WTP well site that produces improved results over the common radial flow models.
 
INTERFERENCE IMPACTS CAUSED BY GROUNDWATER WITHDRAWALS FROM PUBLIC WATER SUPPLY WELLS IN THE CONSOLIDATED SEDIMENTARY ROCK AQUIFERS OF CENTRAL MARYLAND
More than 90% of impacts to about 100 domestic wells can be attributed to withdrawals by Poolesville and Taneytown municipal wells, and dewatering of the Mettiki Coalmine, all in consolidated sedimentary rock formations, and dewatering of limestone quarries throughout the state. This investigation presents case studies of the results of testing and monitoring at the Taneytown well 14 and Poolesville wells 9 and 10 sites. Also, presented is a case study at the Cloverhill III subdivision. Although no impacts are known to have occurred at that site, it is the first project that included mandatory monitoring during several aquifer tests and for which a numerical model was developed. Added to the ¼ fracture length (¼ L) model developed for crystalline rock aquifers was an analytical model for an anisotropic aquifer.

EVALUATION OF POTENTIAL HYDROLOGICAL IMPACTS AND DEVELOPMENT OF SINKHOLES CAUSED BY DEWATERING OF QUARRIES IN THE HAGERSTOWN VALLEY, WASHINGTON COUNTY, MARYLAND
Six case studies investigating the impacts of quarry dewatering within the Hagerstown Valley, Washington County, Maryland are presented. This valley is within the Karst geological region of Maryland, which has natural sinkholes and depressions. Regulations require quarries to be liable for impacts caused by mining activities. For each quarry, a hydrological investigation determined the zone of influence of dewatering, and compared historical pumping rates to the levels of nearby monitoring wells and stream gages to determine possible influences due to dewatering. The Security Quarry, near Hagerstown, and the Boonsboro Quarry contributed to the development of sinkholes nearby. The Security Quarry and the Pinesburg Quarry impacted domestic wells within the zone of influence.

EVALUATION OF POTENTIAL HYDROLOGICAL IMPACTS AND DEVELOPMENT OF SINKHOLES CAUSED BY DEWATERING OF THE FREDERICK AND MEDFORD QUARRIES, WESTERN PIEDMONT PROVINCE, MARYLAND
Case studies investigating the impacts of quarry dewatering within the Frederick and Medford Quarries in the Piedmont region of Maryland are presented. The highest concentration of sinkholes in Frederick County occur in the vicinity of the Frederick Quarry. Changes caused by pumping of groundwater from the quarry and changes in drainage patterns by land development and road construction or a combination of both factors likely caused the formation of sinkholes in the area. The Frederick Quarry dewatering has also lowered the flow rate within nearby Carroll Creek, which has had instances of no detectable flow. Dewatering of the Medford Quarry has directly led to the formation of sinkholes on nearby properties. Flows have been reduced in the nearby Copps Branch, Little Pipe Creek, North Stream, Danner Spring Branch, and Stone Chapel Creek. A biological assessment within the Danner Spring Branch and Stone Chapel creek conducted in 2007 attributed low fish populations to low flows.
 
IMPACTS CAUSED BY GROUNDWATER WITHDRAWALS ON STREAMFLOW, FISHERIES COMMUNITIES AND AQUATIC HABITAT IN THE WESTERN PIEDMONT AND BLUE RIDGE PROVINCES OF MARYLAND
Eight study sites within central Maryland were chosen to evaluate whether groundwater withdrawals were leading to low flow rates in nearby bodies of water. Hollow Creek near Middletown and Linganore Creek near Mt. Airy were found to be impacted by groundwater withdrawals, with extremely low levels observed during the 2002 drought. However, biological sampling after the drought indicated both streams had recovered and were no longer impaired. The major factor affecting biologic integrity scores were land use practices, especially those associated with agricultural activity. Fish communities appear to be impacted mostly by low flows, especially in watersheds with small drainage areas. If refugia exist, fish populations may recover rapidly after droughts. High surface runoff in watersheds underlain by the low permeability soils of the New Oxford Formation may produce naturally low biologic integrity scores that may be mistaken for the effects of urban runoff.