Water samples were collected from four lakes in Byram Township, Sussex County, N.J., in the summer of 1998 as part of an investigation of the occurrence of volatile organic compounds (VOCs) in domestic wells of lakeside communities. Cranberry Lake and Lake Lackawanna are surrounded by densely populated communities where the use of gasoline-powered watercraft is prevalent, and water is supplied by lakeside wells. Forest Lake is surrounded by a densely populated community where the use of gasoline-powered watercraft is prohibited. Stag Pond is privately owned, is situated in a sparsely populated area, and is not navigated by gasoline-powered watercraft. Samples were collected from Cranberry Lake in early summer and again in late summer 1998. Concentrations of the gasoline oxygenate methyl tert-butyl ether (MTBE) ranged from 1.6 to 15.0 µg/L (micrograms per liter) on June 24 and decreased with depth. The depth-related concentration gradient is attributed to density stratification caused by the temperature gradient that is present in the lake during the early summer. MTBE concentrations ranged from 7.4 to 29.0 µg/L on September 8 and were uniform with depth, as was water temperature, indicating that the lake was vertically mixed. On the basis of these concentration profiles, the mass of MTBE in Cranberry Lake was estimated to be 15 kilograms on June 24 and 27 kilograms on September 8. These mass estimates are equal to the amount of MTBE in 52 and 95 gallons, respectively, of gasoline that contains 10 percent MTBE by volume. Concentrations of another gasoline oxygenate, tert-amyl-methyl ether (TAME), ranged from 0.07 to 0.43 µg/L on June 24 and from 0.2 to 0.69 µg/L on September 8. The highest concentrations of benzene, toluene, ethylbenzene, and xylenes (BTEX) were 0.18, 1.2, 0.18, and 0.97 µg/L, respectively, on June 24. All BTEX concentrations in Cranberry Lake on September 8 were less than 0.2 µg/L.

Samples were collected from Lake Lackawanna on September 9. Concentrations of MTBE and TAME ranged from 3.7 to 14.0 µg/L and from 0.17 to 0.38 µg/L, respectively. Like those in Cranberry Lake the previous day, BTEX concentrations were less than 0.2 µg/L, and VOC concentrations and water temperatures were nearly uniform with depth. The mass of MTBE in Lake Lackawanna on September 9 was estimated to be 6 kilograms, which is equal to the amount of MTBE in 21 gallons of gasoline that contains10 percent MTBE by volume. All VOC concentrations were less than 0.2 µg/L in samples collected from Forest Lake on September 8, 1998, and from Stag Pond on the following day.

Oxygenated gasoline is used in watercraft on lakes across northern New Jersey. Many of these lakes are surrounded by communities similar to those at Cranberry Lake and at Lake Lackawanna, which depend largely on wells for water supply. Therefore, a regional assessment of the occurrence of these compounds in lakes and ground water is needed to determine the effect of the use of oxygenated gasoline on water quality in lakeside environments throughout northern New Jersey.