The water levels of streams, rivers, and lakes provide information about variables such as snowmelt, flood peaks, and other changes in hydrologic regimes. Water level is sometimes measured by an individual using a depth meter and physically measuring the water depth in the body of water or in a stilling well near the water source. The alternative to this method is to use expensive instruments and link them to data loggers that continually monitor water level. Each data logger must be connected to several sensors by coaxial cable or twisted pair wires. Using connecting wires is problematic in elevated sites due to lightning and loss of information because of long wires.
Wires interfere with natural wildlife activity.
Expense limits the number of sites that can be monitored. The University of Washington was interested in developing low-cost sensor technology to apply to forestry situations and to take advantage of the education opportunities afforded in developing and applying this technology through their Electrical Engineering Department. The Forest Service was interested because it needs high quality, low-cost technology to measure stream levels. To be most useful, the data should be in an automated format so it can be processed easily and quickly on desktop computers. The technology needs to be durable enough to withstand field conditions, have a minimum of movable parts, and be easy to maintain and operate.