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Rock-Koshkonong Lake District v. DNR, 2013 WI 74

Why this matters: The Wisconsin Supreme Court found the outer edge of the public trust doctrinepublic trust doctrineThe state holds navigable waters and the land beneath them for everyone, and cannot sign that away. Wisconsin's version is written into the state constitution and is among the strongest in the country.. It stops at the ordinary high water markordinary high water markThe physical line on a shoreline showing where water regularly reaches. On a Wisconsin lake your private property stops there and the state owns the bed below it. The DNR decides where the line is, not your deed.. Above that line the DNR still regulates, using police powerpolice powerA government's basic authority to regulate for public health and safety without having to pay you for the restriction. rather than the constitutional trust. For a waterfront buyer, this is the case that tells you where the boundary actually is.

Doctrine: Public trustpublic trust doctrineThe state holds navigable waters and the land beneath them for everyone, and cannot sign that away. Wisconsin's version is written into the state constitution and is among the strongest in the country., ordinary high water markordinary high water markThe physical line on a shoreline showing where water regularly reaches. On a Wisconsin lake your private property stops there and the state owns the bed below it. The DNR decides where the line is, not your deed., agency authority

Case name and citation

Rock-Koshkonong Lake District v. Wisconsin Department of Natural Resources, 2013 WI 74, 350 Wis. 2d 45, 833 N.W.2d 800.

Court and year

Supreme Court of Wisconsin. Decided July 16, 2013. Decided 4 to 3. Opinion by Justice Prosser. Justice Crooks dissented in relevant part.

One-line holding

Public trust jurisdiction does not extend to non-navigable land or non-navigable water above the ordinary high water mark, though the DNR retains broad statutory police powerpolice powerA government's basic authority to regulate for public health and safety without having to pay you for the restriction. authority to protect those resources, and the DNR erred by excluding most evidence of the economic impact of lower water levels.

Facts

Lake Koshkonong is a large, shallow impoundment on the Rock River, regulated by the Indianford Dam.

The Rock-Koshkonong Lake District petitioned the DNR to raise the lake’s water levels. Property owners and businesses around the lake wanted higher water. Wetland and hunting interests intervened on the other side.

The lake’s ordinary high water mark had risen between 1979 and 2001, partly because the dam’s capacity to regulate levels had diminished. The DNR treated 778.11 feet above mean sea level as a representative ordinary high water mark. Higher levels under the petition could push that mark higher still.

The DNR denied the requested increase. In doing so, it relied on the public trust doctrine as authority to protect wetlands adjacent to the lake, including wetlands above the ordinary high water mark, most of which are not navigable in factnavigable in factWisconsin's test for whether a waterway is public. Roughly: can a small recreational boat float on it on a regularly recurring basis. A lot of modest creeks qualify..

The DNR also excluded most testimony about the economic impact of lower water levels on residents, businesses, and the local tax base.

The District challenged both moves, arguing the DNR had improperly expanded its public trust jurisdiction onto private land.

May the DNR invoke the constitutional public trust doctrine to protect non-navigable land and non-navigable wetlands above the ordinary high water mark, and must it consider economic evidence when setting water levels?

Holding and reasoning

The court agreed the DNR properly considered impacts on wetlands in and adjacent to the lake, and held it relied on the wrong source of authority to do it.

On the trust’s limit, the reasoning was structural. Navigabilitynavigable in factWisconsin's test for whether a waterway is public. Roughly: can a small recreational boat float on it on a regularly recurring basis. A lot of modest creeks qualify. is a prerequisite for public trust jurisdiction. Wetlands are often not navigable in fact, and non-navigable land is by definition not navigable. Eliminating navigability from the doctrine “would remove one of the prerequisites for the DNR’s constitutional basis for regulating and controlling water and land.”

The court’s holding: “There is no constitutional foundation for public trust jurisdiction over land, including non-navigable wetlands, that is not below the ordinary high water mark of a navigable lake or stream.”

It added that the consequences for private property owners of the DNR’s broader theory “could be very significant.”

The DNR did not lose its authority, only its constitutional label. The court held the DNR has broad statutory authority grounded in the state’s police power to protect non-navigable wetlands and other non-navigable water resources, and that under Wis. Stat. 31.02(1) it may consider water level impacts on all adjacent property.

The court drew the distinction carefully: “Applying the state’s police power to land above or beyond the OHWM of navigable waters, to protect the public interest in navigable waters, is different from asserting public trust jurisdiction over non-navigable land and water.”

The court also held the DNR may consider Wis. Admin. Code ch. NR 103 water quality standards when making a water level determination affecting wetlands.

On economics, the DNR lost. Excluding most testimony about the economic impact of lower water levels was error. A water level decision necessarily favors some interests and harms others, and the agency must consider all probative evidence.

The court affirmed the breadth of the trust within navigable waters, quoting Diana Shooting Club’s instruction that the trust “should be interpreted in the broad and beneficent spirit that gave rise to it.”

Why it matters

Every doctrine needs a boundary, and this is Wisconsin’s.

After Diana Shooting Club, Muench, Just, and Lake Beulah, the public trust in Wisconsin had grown steadily: from navigation to recreation to scenic beauty to shorelands and wetlands to groundwater feeding surface water. Rock-Koshkonong is where the court said the constitutional version of the doctrine has a geographic limit, and the limit is the ordinary high water mark.

The practical effect is smaller than it sounds, which is the part worth understanding. The DNR can still regulate wetlands above the mark. It just does so under statutory police power, which the legislature could theoretically amend, rather than under a constitutional trust the legislature cannot touch.

That distinction became the central question 8 years later, when the legislature’s Act 21 restrictions were tested against the DNR’s well authority. In Clean Wisconsin (2021), the court found the statutory grants sufficient. See 2021-clean-wisconsin-v-dnr.md.

The economic evidence holding is the underrated part of this case. It means water level decisions must weigh property values and local economies alongside ecology. That cuts in favor of shoreline owners in the next lake level fight.

Note the vote. 4 to 3, with a dissent arguing that the trust extends to surrounding areas including wetlands above the mark, citing the state’s title to land between the ordinary high water marks and its regulatory reach beyond. The boundary here is real and it is not unanimous.

What it means for a landowner today

This case defines the line that matters most for a Wisconsin waterfront parcel.

Practical translation:

  • The ordinary high water mark is the critical boundary. Below it on a navigable lake, the state holds the bed in trust and your ownership is essentially nonexistent. Above it, you own the land, subject to regulation.
  • Regulation above the mark is real and enforceable. Shoreland zoningshoreland zoningCounty rules controlling what you can build within 1,000 feet of a lake or 300 feet of a river. They set your setbacks, your buffer, and how much of the lot you can pave., wetland rules, and DNR authority all operate there. Just v. Marinette County remains good law. See 1972-just-v-marinette-county.md.
  • The ordinary high water mark can move. It shifted on Lake Koshkonong between 1979 and 2001. It is a physical determination based on the water’s continuous presence and action, not a fixed survey line.
  • If you buy on a dammed lake or flowage, water levels are subject to a regulatory order that can change, and the process now must weigh economic impacts on you.

What to verify before closing:

  • The ordinary high water mark location for every water body touching the parcel, established by survey or DNR determination rather than by the seller’s belief.
  • Any water level order governing the lake or flowage, and its history.
  • Wetland delineation, since wetlands above the mark are still regulated.
  • Whether a lake district exists and whether a level petition is pending.

Who verifies: a surveyor for the mark, the Wisconsin DNR for water level orders and navigability, a wetland delineation professional, and a Wisconsin real estate attorney.

Subsequent history / is it still good law

Good law as of July 2026 and the controlling statement of the outer limit of Wisconsin public trust jurisdiction.

It coexists with the expansive cases rather than displacing them. Diana Shooting Club, Muench, Just, and Lake Beulah all remain good law. Rock-Koshkonong locates their geographic edge and reassigns the source of authority above that edge from the constitution to statute.

Clean Wisconsin (2021) then confirmed those statutory grants are adequate despite Wis. Stat. 227.10(2m).

Sources

Research demo, not legal advice. Facts current as of July 2026. Water law is state-specific and moves quickly, so confirm anything you plan to act on with a licensed attorney and the relevant state agency.