Important cache information: You do not need to move or alter the storm drain grate!
Extreme stealth (depending on time of year), Tweezers, BYOP
This geocache is part of a planned series "South Hills Stormwater", that will take geocachers on an interactive and educational tour of the stormwater management features in southeastern Missoula, hiding beneath our feet. As a hydrogeologist, I have always been fascinated with the ways that humans interact with and modify the water cycle. The fate of Pattee Creek, as it travels down Pattee Canyon, and then mysteriously disappears without a trace near Bancroft Ponds inspired me to dig into Missoula's stormwater system and hide this series of geocaches. For more reading, please see the references at the end of the description.
Pattee Creek 100-Year Storm Drain
This geocache will give you a view of the Pattee Creek 100-year Storm Drain. At the mouth of Pattee Canyon near Higgins Ave (GCBK2MD), Pattee Creek enters a stormwater settling pond which diverts flow either into a 60-inch storm drain designed to accommodate a 100-year flood event, or into the above-ground channel that flows down Pattee Creek Drive and feeds Bancroft Ponds. The City of Missoula has the ability and authority to turn on and off this channel by opening or closing a gate valve at the stormwater settling ponds. Depending on the time of year you may see water flowing through the pipe at GZ. This water is diverted to prevent the ditch along Pattee Creek Drive from overflowing. In the event of a serious flood, the storm drain would collect excess runoff through intake drainages like the one at GZ, and carry it to the Bitterroot River Outfall.
Stormwater runoff is the number one source of water pollution in the United States. In the South Hills of Missoula, stormwater is not treated before it enters streams, which means that anything stormwater encounters as it flows along impervious surfaces could end up polluting Pattee Creek and ultimately the Bitterroot River including: trash, debris, sediment, chemicals, fertilizers, dog waste, soap, and car oil.
To continue this geo-series, you can walk along the above-ground portion of Pattee Creek towards Bancroft Ponds or upstream along Pattee Creek Drive towards Pattee Canyon.
I will update this text as more geocaches in this series are added.
Happy Hunting!
References and Further Reading
Butterfield, Carver D. (2024). From Creek to Ditch and Back Again: The History and Future of Pattee Creek, Missoula, Montana. University of Montana. Accessed online at: https://scholarworks.umt.edu/cgi/viewcontent.cgi?article=13460&context=etd.
Missoula Montana Stormwater Portal: https://www.ci.missoula.mt.us/2138/Stormwater
Missoula Montana Interactive Stormwater GIS Portal: https://www.arcgis.com/home/item.html?id=8a179071f15848cf961d3586fc6bf4d5