Visual ID

OR175
Johnson Creek Basin Monitoring


"Holgate Lake"

This is a summary of water level-observations on a feature locally known as Holgate Lake. It is located near the intersection of Southeast Holgate Boulevard and Southeast 136th Avenue on private property. Elevated water levels in this area have caused flooding in the surrounding area, including damage to residences south and west of the lake. The last episode of flooding occurred in the spring of 1999. The USGS, in cooperation with local city and county governments, is studying this occurrence and is providing the public information they can use to protect lives and property.

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:

  • Holgate Lake water level sensor [photograph 52kb] o

  • The auger-drill rig [photograph 68kb] o

  • Core samples used to determine shallow geologic characteristics in the area [photograph 68kb] o

  • The auger drill in action [photograph 88kb] o

  • Installation of the well casing [photograph 67kb] o

  • The finished well [photograph 68kb] o



    Surface and ground-water levels:

  • Real-time water-level data for the well located 0.2 miles southeast of Holgate Lake
  • Holgate Lake levels, including comparison of lake levels to nearby ground-water levels. [graph]o

    Johnson Creek Project Page |
    Last modified: 6/15/00