Preliminary results indicate that the lake is primarily a ground-water feature, as water level in the lake is closely related to the ground-water elevation in the area. Although the lake receives some surface-water inflow, the primary cause of changes in the lake level is change in the shallow ground-water level in the area.
The instruments monitoring this area consist of several components. A gage records the level of the lake hourly. The data are stored on a data recorder at the site, and are retrieved on a regular basis. A shallow auger-drilled well is located on the west side of the lake. As this shallow well is near the lake, and is drilled in relatively pervious material, the elevation of the water surface in this well is very close to the water level of the lake. This well is used to track the recession of the water level when the lake dries up, typically in late summer. In addition, an unused domestic ground-water well, located about 0.2 miles southeast of Holgate Lake, is equipped with a continuous water-level recorder and telephone modem. Water-level data are automatically relayed to the USGS office in Portland, and are available for viewing real-time on the internet by the public.
Photographs of the instrumentation used in monitoring the hydrology of the Holgate Lake area:
Surface and ground-water levels: