When you're boating across Castle Rock Lake, it's easy to think about what's around you — the shoreline, islands, beaches and nearly 14,000 acres of water.

But have you ever wondered what's underneath you?

We recently did.

While boating between Juneau County Castle Rock Park and Castle Rock Dam, we could see what appeared to be man-made shapes or structures beneath the water.

Were they foundations? An old road? Remnants from construction of the flowage? Something else entirely?

We can't say for certain what we were looking at.

But here's the fascinating part:

There really is history underneath Castle Rock Lake.

Before Castle Rock Lake Was a Lake

Castle Rock Lake is a man-made flowage created by damming the Wisconsin River.

Before the water rose, this wasn't a lake bottom. The landscape included the original Wisconsin River channel, farmland, forests, roads and communities.

Wisconsin River Power Company describes the original lakebed as a mixture of cleared farmland, prairie and forested knolls divided by the winding Wisconsin River.

When Castle Rock Dam was constructed and the reservoir filled, that landscape changed forever.

And some of it disappeared beneath the water.

The Lost Communities of the Castle Rock Area

One of the most fascinating parts of Castle Rock Lake history is that communities once existed in areas affected by the creation of the flowage.

Werner

The former community of Werner was located in what is now the Castle Rock Lake area on the Juneau County side.

According to the Town of Germantown's documented history, the site of Werner was submerged beneath Castle Rock Lake when the flowage was created.

Even the cemetery was affected. Graves from Werner Cemetery were relocated to higher ground at Germantown Cemetery before the area was flooded.

That's not folklore or a lake legend.

There really was a community where there is water today.

Germantown

The historic community of Germantown was located near the Wisconsin and Yellow rivers.

When land was acquired for creation of the reservoir, buildings from the old village were dismantled, and some of the materials were reportedly reused to build homes in Mauston.

Today, the former Germantown area is associated with Juneau County's Castle Rock Park.

That makes boating around this part of Castle Rock especially interesting. The shoreline we know today looks completely different from the landscape people would have recognized generations ago.

Quincy

Across the Wisconsin River on the Adams County side was another historic settlement: Quincy.

The Germantown Ferry once crossed the Wisconsin River between the Germantown/Werner area and Quincy.

Quincy had its own community history long before Castle Rock Lake existed.

So What Can You Actually See Under Castle Rock Lake?

That's where things get interesting — and where we're careful not to turn a good story into a tall tale.

The bottom of Castle Rock Lake contains the remains of a landscape that existed before the reservoir.

Depending on location, water level and visibility, things that appear surprisingly structural could potentially include:

  • Old roadbeds or paths

  • Foundations or remnants of former structures

  • Tree stumps left from the pre-flowage landscape

  • Old riverbank features

  • Rock or concrete

  • Remnants associated with construction of the dam or reservoir

Modern fish finders and side-imaging sonar can make these underwater features even more noticeable.

But seeing something rectangular on the bottom doesn't automatically mean you've discovered somebody's old farmhouse.

And that's exactly why the mystery is so much fun.

What Did We See Near Castle Rock Dam?

We honestly don't know yet.

We could see what appeared to be structures beneath the water while boating between Juneau County Castle Rock Park and Castle Rock Dam.

Knowing the documented history of this area certainly makes you look at those shapes differently.

Could we have been looking at remnants of Castle Rock Lake's pre-1950s landscape?

Possibly.

Could there be a much less exciting explanation?

Absolutely. 😂

Until we can compare the exact location with historic maps and old plat records, we're leaving this one in the “very interesting and we're going to keep digging” category.

Castle Rock Lake Is More Than What You See From the Boat

This is one of the things we love about spending time on Castle Rock Lake.

You can boat across the same stretch of water dozens of times and then learn something that completely changes the way you look at it.

Underneath today's lake are traces of the Wisconsin River's old path, former farmland and pieces of communities that existed long before anyone was cruising across Castle Rock on a pontoon.

So the next time you're out on Castle Rock Lake and your fish finder shows something strange on the bottom…

You might be looking at a stump.

You might be looking at rocks.

You might be looking at something left behind when the lake was created.

Or you might be floating directly over a little piece of Wisconsin history.

And now we're definitely going to be paying closer attention to that fish finder. 👀🚤

Sources & Further Reading

Wisconsin River Power Company — Castle Rock Project and history
https://www.wisconsinriverpower.com/castlerock

Town of Germantown — Community history, including Germantown, Werner and the former ferry
https://townofgermantown.com/community/

Wisconsin DNR — Buckhorn State Park history and the former Germantown/Werner area
https://dnr.wisconsin.gov/topic/parks/buckhorn/history

Wisconsin DNR — Wisconsin Submerged Cultural Resources
https://dnr.wisconsin.gov/topic/Lands/CulturalRes/submerged.html

Lakes Region Team
Exploring Castle Rock Lake from the shoreline to whatever the heck is hiding underneath it. 🚤