Ground water well elevation for Niwot Ridge Saddle 2012- ongoing

Water level of Saddle Ground Water Wells. Ground Water Well locations, depths, and design were determined by Niwot Ridge LTER lead researchers, Mark Williams and Nel Caine, to monitor groundwater chemistry and water levels. Well locations were selected based on proximity to the headwater region of the Saddle stream channel. Ground Water Wells are located along an east-west transect at the Saddle site, each pair consisting of a deep well to a depth between 6.3 and 8.8 m, and a shallow well to a depth of 1.5 m. Ground surface elevations at the Saddle wells range from about 3522 m at the eastern wells to 3532 m at the western wells. The transect is roughly 170 m from east to west, has an average slope of 0.06, and is perpendicular to the Saddle stream. Saddle pair 3 was installed very close to the channel. Saddle pairs 2 and 4 were installed on opposite sides of the channel. Saddle pair 1 was installed furthest from the channel (King, 2012). Ground water wells were installed in October 2005 by Bandimere Geothermal Drilling Systems. Wells are cased with 2-inch nominal pipe size, Schedule 40 polyvinyl chloride (PVC), flush-threaded pipe. Well screens were constructed from 0.020-inch continuous slot PVC and installed in 5-ft (1.52 m) intervals. All of the wells have 1.52 m screens at the bottom of the well. The bottoms of the wells were capped with a PVC flush-threaded point cap. The annular space around each screen and pipe was backfilled with #10-20 silica sand to act as a filter (King, 2012). The Niwot Ridge LTER monitoring of these Ground Water Wells has varied over the years since the wells were installed. Prior to 2014, all wells were sampled weekly in summer and monthly in winter for chemistry, and alternating wells were monitored for water level with pressure transducers and a weighted tape measure. From 2015 through present, Saddle Deep 3 (SD3) and Saddle Deep 4 (SD4)- those located closest to the Saddle Stream headwaters- are being monitored for water level, water temperature and chemistry. Depth to water and temperature are recorded at 12 hour intervals by a Solonist Pressure Transducer. Additional water level measurements are taken weekly from snowmelt through end of September, and monthly from October through snowmelt, with a weighted tape measure and compared to pressure transduce voltage to convert voltage to depth below surface.