Methane and nitrogen have critically important biogeochemical cycles. Methane is a strong greenhouse gas, while nitrogen is a eutrophication agent in estuarine and coastal systems. This thesis investigates the presence of methane and nitrogen in groundwater and streams as well as any linkages between these biogeochemical cycles. In agricultural groundwater with elevated nitrogen concentrations, dissolved methane concentrations ranged from 0 to over 400 M. Restored streams in forested and urban watersheds had a range of methane concentrations from 0 to 5.37 M. The impact of land use was investigated as well, finding that within 3-5 years after the cessation of intensive grain production, groundwater nitrate concentrations in the top of the surface unconfined aquifer dropped from 11 mg NO3--N L-1 to 0.5 mg NO3--N L-1. Biogeochemical methods were used to investigate the process of anaerobic oxidation of methane coupled to denitrification in agricultural soils and groundwater.