McHenry Lock & Dam

Last weekend, when we had a tease of spring in the air, we took a hike at Moraine Hills State Park with a quick trip to the McHenry dam. It was a dam great day to go!

Stolen directly from the Moraine Hills Website, an excerpt on the local geology:

The 48-acre Lake Defiance, located near the center of the park, was formed when a large portion of ice broke away from the main glacier and melted. Lake Defiance is gradually filling in with peat from its unstable shoreline. The lake is one of the few glacial lakes in Illinois that has remained largely undeveloped, maintaining a near-natural condition.

Pike Marsh, a 115-acre area in the southeast corner of the park, is home to many rare plants. Its outer fen area (a very rare marsh wetland) includes Ohio goldenrod, Kalm’s lobelia, dwarf birch and hoary willow, while cattails and bulrushes grow in its interior. Pike Marsh also supports one of the state’s largest known colonies of pitcher plants, which attract, trap and digest insects.

The 120-acre region known as Leatherleaf Bog is an excellent example of kettle-moraine topography. In geological terms, a kettle is a depression formed when an isolated block of glacial ice melts. The bog consists of a floating mat of sphagnum moss and leatherleaf surrounded by a moat of water. Marsh fern, marsh marigold, St. John’s wort and several species of willow put down roots here. Because both Pike Marsh and Leatherleaf Bog are dedicated nature preserves, they are protected by law.

Moraine Hills offers three examples of wetland enhancements. Yellow-head, Black Tern and Opossum Run marshes are samples of what can be accomplished with a little help from man.


This is part of Possosum Run Marsh.


Lake Defiance in the background. Someone is waking up!


Sandhill Cranes! They are all over the place. Rumor has it that they are the true heralds of spring as they don’t migrate until the weather is truly going to turn nice.


When I was here two years ago, the water as very high and running over this part of the dam. They are working on the lock system in the background.


Β© Ilex ~ Midwestern Plant Girl

29 thoughts on “McHenry Lock & Dam

  1. The marshes have such beautiful views πŸ™‚ I too visited a hydro-power-dam a couple of months back and it was actually a picnic spot much like yours πŸ™‚ Good to know that human interference has been minimum so far. Did you click any pitcher plants ?


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