Observation Well Information

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Introduction

The Province operates a network of observation wells to provide data on ground water level fluctuations and ground water quality information on developed aquifers in British Columbia. Observation well water levels are monitored using one of four methods: 1) manually with a wetted tape, 2) continuously using Steven's chart recorders, 3) electronically with data loggers or 4) remote monitoring using cellphone technology.

Water level data from observation wells are collected on a monthly basis by field observers and forwarded to Regional Offices. Data are then checked for errors and ommissions and forwarded to the Water and Air Monitoring and Reporting Section for final checking and storage. Water level data are referenced from ground level and the month end water level reading are entered and stored in Excel to produce a month-end hydrograph. The method of measurement and accuracy of each method are given below:

Method of measurement Accuracy
Wetted Tape Method +/- 1 mm
Steven's Chart Recorder +/- 1 mm
Data Logger +/- 0.1 %

Mayne Island observation well graph

Hydrograph Analysis- Observation Well No.125

The hydrograph above shows the change in ground water level in the observation well (meters below ground level) over time. This observation well is monitored manually each month using a wetted tape. This observation well is located in a ditch along the side of Horton Bay Road.

Observation well No.125 is located in an undelineated, bedrock aquifer to a depth of 30.5 m. Since 1971, the ground water level in the well has ranged from a high of 0.5 m above ground level in December 1975, to a low of 1.4 m below ground level in August 1994. The difference between maximum and minimum ground water levels in any single year ranges from approximately 0.5 (in 2001) to 1.0 (in 1981) meters. The lowest ground water level period in the hydrograph is during August to September. Levels usually begin to rise late September to October, corresponding to ground water recharge from seasonal precipitation. Between 1971 and 1977, the well experienced flowing artesian conditions during the winter months. Since 1981, the well no longer flows, as the ground water level has declined. Overall, the ground water level in the well has been gradually declining since the mid-1970's.

NOTE* Detailed water level information for this well is available in Excel Format.
For more information, please email
groundwater@gov.bc.ca