Sediment, stream, and canopy characteristics were measured in four headwater stream associated with methane ebullition monitoring. Within each stream 3-4 patches were selected for monitoring, and the following variables were measured at each patch: canopy cover, water depth, sediment organic matter content, the percent sediment less than 2mm in diameter, sediment depth, sediment % carbon, and sediment % nitrogen were measured.

Canopy cover was estimated using a convex spherical densiometer (Forestry Suppliers, Inc., Model-C, Mississippi, USA) at each patch within each stream. Water depth was found using the mean of 10 locations measured with a meter stick in each patch. Following Crawford and Stanley (2016), depth to refusal was measured as a means of approximating the depth of sediments overlying hard mineral sediments. Fifteen measurements were made at each patch, five measurements along three replicate channel cross-sections, and the average was used as the patch metric. Finally, sediment cores were collected near all patches and separated into subsamples representing 5 cm depth intervals from 0 cm to the deepest collected sample (maximum sampling depth varied from 10 to 35 cm). A Multi Stage Soil Core Sampler (AMS, Inc., Idaho, USA), which consists of a stainless steel cylinder and a 5 cm diameter plastic liner, was driven into the stream sediments using a sliding weight stand (Wik et al. 2018). Sediment cores were located at least 1 m away from traps to minimize disturbance. Subsamples were analyzed for OM content by loss of mass on ignition. The percent of sediment smaller than 2 mm in diameter was determined by passing subsamples through a 2 mm sieve and weighing each fraction. Finally, sediment carbon and nitrogen content were measured on dry pulverized samples by elemental analysis using a Thermo FlashEA Series 1112 at the USDA Forest Service, Louis C. Wyman Forest Sciences Laboratory in Durham, NH.