The sampling of the riverine-to-marine transect (Penobscot River, Penobscot Bay, and the Gulf of Maine) took place in 2008. Water samples were collected and filtered in the field using 0.45 micrometer capsule filters (Versapor membrane), silicon tubing, and a peristaltic pump. Water samples were then shipped on ice to the U.S. Geological Survey in Boulder, Colorado and chilled to approximately 4 degrees Celsius until analysis. Dissolved organic matter (DOM) was separated into fractions by an isolation method that passes aqueous sample through Amberlite XAD8 and XAD4 resins using low pressure liquid chromatography. The hydrophobic organic acid (HPOA) fraction is the eluate from the XAD8 fractionation column and the transphilic organic acid (TPIA) fraction is the eluate from the XAD4 fractionation column. Dissolved organic carbon (DOC) was either analyzed on a Shimadzu TOC-Vcph total organic carbon analyzer by combustion-infrared or an OI700 Analytical total organic carbon analyzer by wet-oxidation; each sample was measured in replicate and the average was reported. Ultraviolet (UV) absorbance at the wavelength of 254 nm was measured with an Agilent HP8453 UV-Vis spectrophotometer. Specific UV Absorbance (SUVA) at 254 nm is a calculated parameter defined as the UV absorbance at a wavelength of 254 nm in absorbance units per centimeter divided by the DOC concentration in milligrams per liter and then multiplied by 100. SUVA 254 nm is reported in units of liters per milligram carbon per meter and correlates with the percent aromatic carbon of the DOM. Associated laboratory quality assurance and quality control measures have been taken to produce final data.