An April decision by Montana’s Supreme Court legally established something that the scientific community has long agreed upon: that groundwater is connected to surface water.

In 1993, Montana state legislators ordered a moratorium on new water-rights applications for surface water in the over-allocated Upper Missouri River Basin — along with all groundwater "immediately or directly connected" to surface water. That didn’t stop Montana’s Department of Natural Resources and Conservation from processing new water-use permits, however. Arguing that the groundwater pumped from the new wells was not "immediately or directly connected" to any surface water, the department said it was not subject to the moratorium.

Montana Trout Unlimited and a coalition of 11 ranchers and landowners with senior water rights in the Basin disagreed and filed suit against the department in 2003. Last month, the state Supreme Court ruled 4-3 in favor of Trout Unlimited, saying that the department’s interpretation of groundwater failed to follow the intent of the law.

Mary Sexton, director of the state Department of Conservation and Natural Resources, calls the decision a "wakeup call" for her agency as well for the Montana Legislature. It will have implications for water rights across the state, Sexton says.

Her department is hoping to write legislation in 2007 that would force new users, such as developers, to purchase existing water rights, rather than simply drilling new wells and claiming the groundwater as "new" water.