## Facts

- Park County Sportsmen’s Ranch, LLP (PCSR) owned ranch lands in South Park, Colorado, and sought a water-rights decree for an integrated plan to divert, store, recharge, and later withdraw water.
- The plan relied in part on storing water in naturally occurring underground aquifers that extended beneath multiple parcels, including adjacent land owned by other private landowners.
- PCSR’s proposal contemplated injecting water into the aquifer system; the stored water would migrate through the natural aquifer, including beneath neighboring property.
- The neighboring landowners and the county asserted that the subsurface “storage space” (pore space) beneath their land was their property and that PCSR’s use of it without consent would be a trespass.
- They also claimed that authorizing storage in the aquifer under their land would amount to an unconstitutional taking requiring just compensation.
- The water court entered judgment for PCSR, concluding that using the natural aquifer for underground storage under these circumstances was not trespass and did not require compensation because PCSR proposed no physical facilities on or under the neighbors’ land.

## Issues

1. Whether surface owners have a legally protected property interest in naturally occurring underground aquifers or pore space beneath their land that makes an appropriator’s underground storage of water a trespass.
2. Whether authorizing underground storage in natural aquifers beneath another’s land constitutes a compensable taking when no physical structures are placed on or under that land.
3. How Colorado’s prior-appropriation system defines landowner interests in naturally moving groundwater and the subsurface formations through which it travels.

## Decision

- The Colorado Supreme Court affirmed the judgment for PCSR.
- The court held that a landowner has no property right in the natural movement of groundwater through underground aquifers beneath the land.
- Because the asserted interest in natural aquifer “storage space” was not a cognizable property right that could exclude the movement or storage of water subject to water-rights administration, PCSR’s proposed storage did not constitute trespass.
- For the same reason, approval of PCSR’s storage plan did not effect a compensable taking.
- The court distinguished cases involving physical structures placed on or under another’s land, noting that such installations may trigger the right to exclude and may require consent or compensation, but no such structures were proposed here.

## Legal Principles

- In Colorado, water is administered under prior appropriation; landownership does not confer ownership of naturally flowing or percolating groundwater moving through the hydrologic system.
- Trespass requires invasion of a legally protected property interest; the mere presence or movement of water through a natural aquifer beneath another’s land, pursuant to valid water rights and without installed facilities on that land, is not trespass.
- A takings claim requires a recognized, compensable property interest; absent such an interest in the natural aquifer’s water movement or storage capacity, there is no taking.
- The legal treatment of natural subsurface formations used by water moving through the hydrologic system differs from the treatment of artificial, fixed structures constructed in the subsurface of another’s property.

## Conclusion

The court held that neighboring landowners could not block or obtain compensation for PCSR’s storage of water in naturally occurring aquifers beneath their land because Colorado law does not recognize a landowner property interest in the natural movement or storage of groundwater in those formations, and no physical structures were placed on or under the neighbors’ property.


Bd. of Cnty. Comm’rs v. Park Cnty. Sportsmen’s Ranch, LLP, 45 P.3d 693 (Colo. 2002)