Floods: A tale of two fans
It's summertime in Waterton and those in the know often escape the bustling crowds in town by going to a quiet swimming spot and picnic area known as Marquis Hole. It is a trip connected to a story - a tale started thousands of years ago.
Back then, glacier meltwaters carried materials eroded from the mountains down what are now Cameron and Blakiston creeks and dropped them into the Waterton Lakes. These deposits are now known as the Blakiston and townsite alluvial fans.
These fan-shaped landforms are built up and maintained by floods. Floodwaters flush new sediments eroded from the mountains onto each fan's surface, rearrange existing gravels, rocks and soil, and redirect stream channels. The legends of past floods can be seen in the many dry, abandoned stream channels still visible on the fan's surface.
Alluvial fans are important wildlife habitats . Nutrient-rich fescue grasses covered the well drained soils of the Blakiston and townsite fans. Usually blown free of snow during winter by Waterton's winds, these grasses provide a key winter food source for ungulates, particularly elk and mule deer. Ungulates can also escape the same winds in sheltering aspen groves which rim each fan. Today, the Blakiston and townsite fans have much in common, but they also have some important differences. The story continues
The Townsite Fan was formed at the base of Cameron Falls. It originally was covered with fescue grasses and aspen groves, much as the present-day Blakiston fan is. Today, the town is the dominant feature of this landscape, and native plants have largely been replaced by lawns and garden plants.
While natural processes will never be completely prevented, large floods that could damage the town's roads, campground, businesses and homes are controlled. Cameron Creek has been contained in its channel by rock and wire. When massive floods occur and wash over the banks, the debris is removed by trucks and damages repaired. This ultimately affects the processes that maintain this landform.
Interestingly, the townsite alluvial fan continues to provide vital wildlife habitat. Cultivated grasses and shrubs have only enhanced this area for some wildlife, like deer, bighorn sheep and ground squirrels. These animals are not tame, but they are no longer fully wild either. The townsite also retains a reputation as an excellent place in the park to see birds. On the other hand, predators such as cougars or coyotes can't maintain their normal presence here, and if seen, are mainly passing through. Those that stay are likely to be relocated. This is a place where the needs of people and wildlife must be balanced, and challenges arise as we learn to live with wildlife.
The Blakiston Fan, created and maintained by Blakiston Creek, is the largest alluvial fan in Waterton. It bisects what was once one large lake into what are now known as the Lower and Middle Waterton Lakes. In spring, an amazing variety of wildflowers carpet the ground. In fall and winter, herds of hundreds of elk live there, as do birds, bears, deer and coyotes. In summer, it is a popular place for horseback riding, swimming, picnicking and fishing - especially at Marquis Hole. It is a wild and scenic location, where nature rules.
And nature once again did rule. In 1995, a huge flood hit the park and our story took a twist.
The flood, triggered by massive rains and melting snow, swept across the fan. Blakiston Creek shifted. The gravel road to Marquis Hole became a torrent, making it impassable. Park managers were left with a difficult decision. Do they repair the road and prevent further flood damage or should they let nature take its course?
Nature or nurture
The Park Management Plan provides clear direction that natural processes must function unhindered, and that park staff avoid manipulating natural processes and keep disturbance of landforms to a minimum. This means building a berm or a permanent diversion of the creek are not possible options. However, many local people want access to their favourite picnic area re-established. This would require rebuilding the road every year after high spring waters receed, an expensive ongoing cost.
Another alternative is for people to walk into the area, a short distance for most, but difficult for the young or elderly, or those hauling the family picnic and recreation gear.
Which would you choose?
At meetings held late last year between the park and the community, it was mutually agreed that, while the creek would be allowed to find its natural course, some roadwork could be done to divert runoff water away from the lower part of Marquis Hole. This would allow unpredictable natural water flows to continue, while reducing road damage, the length of time required to keep the road closed, and the costs of reopening it.
The concentration of ungulates and other animals found on the Blakiston and townsite fans presents some of the park's best wildlife viewing opportunities. It is evidence of the importance of alluvial fans. Understanding the similarities and differences between the two fans brings a new appreciation to ecosystem processes, conservation issues and traditional land use.
Ultimately, while a flood helps construct vital wildlife habitat, it can damage human conveniences. In the townsite, it is the natural processes that have been restricted and closely managed. Out on the Blakiston fan, the challenge is for us to adapt to natural change.