A Large-Scale Field Assessment of Underwater Epoxy Use to Install Annual Temperature Monitoring Sites in Rivers and Streams

Modern digital temperature sensors can provide accurate and repeated temperature measurements that span multiple years but are rarely deployed for more than a few summer months due to concerns that annual floods will destroy sensors. We developed an inexpensive installation protocol that uses underwater epoxy to glue sensors to large rocks or cement structures in streams so that annual temperature monitoring is convenient. Field trials suggest epoxied sensors yield unbiased measurements when used in conjunction with solar shields. A large field assessment was initiated during the summers 2010 - 2012 wherein 583 temperature monitoring sites were established in a diverse set of streams across the northwest U.S. Revisits to 179 sites indicate good sensor retention rates, with 90% of sensors retained after one year in low-gradient streams (< 3%) and 75% retained in high-gradient streams (> 3%). The epoxy technique can be used to install sensors rapidly (~20 minutes) in a wide range of temperatures (2˚C – 20˚C). The technique is cost effective because it reduces the number of site visits to < 1/year and a site installation costs only ~$120 (primarily sensor costs). To access a copy of the protocol, visit the TreeSearch website (http://www.treesearch.fs.fed.us/pubs/44251).