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Posted on: July 12, 2018

Lake Levels and Drainage

180627 Gertrude Outfall

Lake Levels and Drainage


The City of Mount Dora recently received an email from a concerned citizen about Lake Gertrude’s water levels and drainage.  We wanted to clarify any concerns, not just with Lake Gertrude, but with other water areas in the City when it comes to drought and recent rain.


Pursuant to a query about Lake Gertrude water levels, the Public Works Director researched historic information and found the following facts on Lake Gertrude: The outflow elevation on the outfall structure (Outfall structure is the apparatus through which water exits the lake. In this case, it’s a 24-inch reinforced concrete pipe) at Oakland Drive is 70.23 feet NGVD (Sea Level).  Seasonal High Water Elevation (SHWE) on Lake Gertrude is 71.86 feet NGVD. The lake level is approximately 6 inches above invert elevation. That means the lake level today (7/9/18) is at about 70.73 feet NGVD, or 12 to 14 inches below SHWE.


SHWE is the seasonal high water mark from year to year.


It does not mean that the lake necessarily will reach that elevation every year, but it should be anticipated. We have had several dry years since 2006 in which all the lake and groundwater levels have dropped lower than normal and some flowing streams have dried up. The wet seasons the city had last year and, so far this year, have recharged groundwater, wetlands, lakes and streams to the degree that levels are returning somewhat back to normal. SHWE also should not be interpreted to mean that lake levels will not go above that elevation in wetter-than-normal seasons. Fluctuations between wet cycles and dry cycles will cause the lake to peak at higher and lower elevations.


Docks built at or below SHWE may be expected to flood on occasion.


The city recommends that property owners who are building docks on any lake should have their contractor shoot elevations from a registered benchmark and ascertain official lake levels from authorized sources (WMD, LCWA, etc.) before building. It will not guarantee that a dock won’t flood in extreme weather, but it should be okay under normal conditions.


Public Works teams checked the drain at Lake Gertrude and found no obstructions in the discharge line. Everything is flowing as designed.


Thank you for allowing us to serve you.


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