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Nonpoint‐source pollution from agriculture can cause the degradation of groundwater and surface water. Some studies conducted in Coastal Plain aquifers have shown NO−3 removal from groundwater due to assimilation by vegetation or denitrification before discharge to a stream is significant; relatively few have been conducted on other physiographic and geological regions within the Chesapeake Bay watershed. This study was conducted at the boundary of the Valley and Ridge and Appalachian Plateau physiographic provinces to understand how the hydrological and geochemical conditions in this region effect the transport and removal of NO−3. The groundwater flow system at the farm studied, located at the base of a valley, is influenced by one groundwater flow component parallel to the axis of the valley and a second flowing perpendicular to the axis having been recharged from topographic highs along the sides of the valley. The axis‐perpendicular component is transporting NO−3 and Cl− applied as fertilizers and manure on an upgradient field and also Cl− from salting of an adjacent road to the study site. The relatively nutrient‐free water from the axis‐parallel component dilutes NO−3 and Cl− concentrations at the site from seasonal averages of 11 mg N/L and 90 mg Cl/L to levels <0.4 mg N/L and 1 mg Cl/L, respectively. Some evidence exists for NO−3 removal from groundwater <3 m belowground; however, it is difficult to confirm the removal process with dilution dominating the system.

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Hydrogeologic factors influencing well yields in folded and faulted Cambro‐Ordovician carbonate rocks and shales were investigated in central Pennsylvania. Productivity values (in gallons per minute per foot of drawdown per foot of saturated thickness) were obtained from 80 wells, the geometric mean value being 19.00, and were grouped into various categories according to well location. Productivities for the various categories were ranked and plotted against the percentage of wells on logarithmic probability paper. Parametric and nonparametric statistical tests were applied; the results of the nonparametric tests are presented. Fracture trace wells were more productive than nonfracture trace wells. Accidentally located fracture trace wells were as productive as intentionally located fracture trace wells because the accidentally located wells were clustered in more productive rocks. The success ratio of accidentally locating a fracture trace well is 4:6. Wells in sandy dolomite and coarse‐grained dolomites were the best producers; wells in valley bottoms were more productive than those in valley walls and uplands; anticlinal wells were better producers than synclina wells; and wells in beds dipping at less than 15° had higher yields than others. The Upper Sandy dolomite member and the Nittany dolomite have similar aquifer characteristics, which are significantly different from those of Bellefonte dolomite, limestones, and shales.

No abstract