FORMATION OF
LAKE RONKONKOMA

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HOW WAS LAKE RONKONKOMA FORMED?

Lake Ronkonkoma is the biggest of eight kettle lakes located throughout Long Island and was formed when a large block of ice became detached from the glacial front during the Pleistocene Glaciation, an event that occurred some 17,000 years ago. After the ice retreated, it left a depression, and ground water filled the hole that was deep enough to tap the underground water table. This accounts for the water always being fresh. It would be virtually impossible to drain the lake even with years of pumping.

The lake varies in size from approximately 215 acres during average drought periods to 275 acres during flooding conditions. The average depth of the lake is approximately 14.5 feet deep, with two deep holes in the southwestern section (45 feet and 90 feet).

KETTLE LAKES (also known as Kettles or Kettle Holes):

A circular depression in a glacial outwash drift made by the melting of a detached mass of glacial ice that became wholly or partially buried.
The occurrence of these stranded ice masses is thought to be the result of gradual accumulation of outwash atop the irregular glacier terminus.
(see image below)

Kettles may range in size from 5m (15 feet) to 13km (8 miles) in diameter and up to 45 m in depth. When filled in with water they are called
KETTLE LAKES. Most kettles are circular in shape because melting blocks of ice tend to become rounded; distorted or branching depressions
may result from extremely irregular ice masses.

Two types of kettles are recognized: a depression formed from a partially buried ice mass by the sliding of unsupported sediment into the space
left by the ice and a depression formed from a completely buried mass by the collapse of overlying sediment

In the United States, kettle holes are common in Wisconsin, Minnesota, New York, and New England. The largest lake on Long Island,
LAKE RONKONKOMA, is a kettle hole.

Kettle Lakes