Photo montage of CWLP scenes with CWLP seal and link to CWLP home page. Click on words City Water, Light and Power to link to home page.

How Lake Water Levels Are Measured

When at full pool, the lake's elevation is 560 feet above sea level. (The official elevation, as provided by the United States Geological Service is 559.35 feet above sea level, but the utility uses the "CWLP datum" of 560 feet.)

This is a photo of the man in the hardhat as he is pulling the measuring stick out of the whole. The lower portion of the stick is wet. The line at which the wetness ends marks the level of the lake.
When the stick is removed, the water line provides a visible and true measure of the lake's level.
This is a photo of a man in a hard hat holding the end of a measuring stick, most of which has been dropped into a small hole in the cement floor.
A Water Purification Plant operator inserts a measuring stick into a small hole in the floor of the subbasement at Lakeside Power Station to measure the level of the lake water below.
 

CWLP uses two methods to measure the lake's level. The first, a
continuous, high-tech option, bounces sonic waves off the surface of the lake. The second employs a low-tech measuring stick. Surprisingly, the second method, in use since the lake was built in 1935, provides the most accurate reading.

This measurement is taken in the basement of Lakeside Power Station, which contains a series of pumps used to direct lake water to the filter plant. A tunnel joining the basement to the lake allows the basement's pumping chamber to fill to the exact level of the lake at the intake tower outside. Water Division operators dip a marked stick into the water to read its depth every two hours. Because there is no wave action in the basement, operators are able to get a precise measurement, which is used as the official reading.



Lake Water Level

How Lake Water Levels Are Maintained

Lake Levels



Last updated: 06/09/10