Forest to Faucet: Bozeman’s Watershed Sustains Water Supplies

Lain Leoniak

After taking friends hiking above Hyalite Reservoir last summer, we sat on the back deck enjoying the beautiful evening.  Sporadic lightening strikes could be seen to the southwest. Conversation turned toward the intense wildfire season throughout the West and how lucky we had been in Bozeman to have made it to late August without a major fire. Dusk turned to dark and we said our goodnights. Unable to sleep, I thought about the conversation and that luck was really the only thing protecting our watershed from a devastating wildfire and that, unfortunately, luck tends to run out.

Bozeman’s forested watershed covers roughly 50,000 acres and although it provides habitat for fish and wildlife, recreation, and wilderness, its most important output may be water.  Bozeman’s demand for water will continue to increase, and the role of clean water from forests will become better understood as an ecosystem service of great value. Many factors impacting water supplies from forests include a changing climate, wildfires, insect outbreaks, and urban sprawl. Bozeman’s watershed forests of the future will need to be managed as much for a sustainable supply of clean water as any other goal.

Nature not only provides our freshwater, it can also help us efficiently and sustainably manage and protect it.  A healthy watershed acts like a sponge, absorbing, storing, and slowly releasing water.  Bozeman’s watershed collects snowmelt for our use throughout  the year. Some of it is intercepted and used by trees and other vegetation. Some flows overland into our reservoir, streams and rivers. Some soaks into the soil, which filters the water as it travels downward to be stored in underground aquifers on its way to the Gallatin River. It may re-emerge at a stream or spring or it can remain underground for a period of time ranging from days to many years.

The plants and soil, and the microbes that live in them, do much of the work in a watershed. In forests and floodplains, wetlands and prairies, they work behind the scenes to filter, store and produce clean water. Taking care of the soil and vegetation with vegetation management and natural infrastructure projects enhances their ability to do those jobs.  Forest vegetation and soils, if healthy and intact, can benefit human water supplies by controlling water yield, peak flows, low flows, sediment levels, water chemistry and quality.

Over the next twenty years, Bozeman’s population is expected to increase by forty percent. However, our current water supplies have and always will be roughly the same. As Bozeman’s population grows, demand for water will increase, putting greater pressure on our watersheds and the water security of our community. At our current rate, by 2036, we are likely to face a scenario in which our demand for water exceeds our available supply.  The choices we make today about where and how development in Bozeman occurs will have a big impact on the city’s future.

This will require a shift in how we think about our watersheds. The federal legislation that created the forest service all the way back in 1897 declared that “[n]o national forest shall be established, except to improve and protect the forest… or for the purpose of securing favorable conditions of water flows.” But, for the last several decades, we have forgotten that projects to preserve and enhance healthy forests are effective ways to secure our future water supplies.
The traditional approach to meeting water demands with built infrastructure is not sustainable without changing the way we develop, build and operate. To create a more sustainable and efficient water future, we must circle back to an old concept and look for ways to protect Bozeman’s watershed and integrate forest vegetation management and natural infrastructure into our built infrastructure solutions. Exploring options for pursuing projects that protect, support and enhance the forests, rivers and wetlands on which we depend for our water is key. Remember, there is no upstream for us!  

For most of us, hearing the term “infrastructure” makes us think of dams, pipes, bridges, train tracks and interstate highways. But infrastructure is so much more than just the man-made systems of concrete and steel.  Infrastructure also includes forests, wetlands, rivers and streams– the natural systems that provide crucial services that we depend on.

To ensure these ecosystem functions and associated benefits continue, options include projects to strategically secure networks of natural lands, working landscapes, and other open spaces as natural infrastructure.

While concrete-and-steel built infrastructure will continue to play a critical role in water storage and treatment, investing in natural infrastructure can reduce or avoid costs and enhance water services and security as part of an integrated system to cost-effectively deliver safe drinking water. Promising efforts in other places across the country have secured natural infrastructure for water management objectives through a variety of means—from land acquisition, zoning ordinances, and conservation easements to catastrophic wildfire risk mitigation and payments to private landowners for best management practices.

In its current state, a wildfire event in Bozeman’s watershed could result in increased levels of sediment that would likely overwhelm the city’s water treatment plant. This could have massive economic impacts to our community.  Moreover, forest chemicals, including those used to fight fire, can adversely affect aquatic ecosystems, especially if they are applied directly to water bodies or wet soil.  Natural infrastructure projects are far less expensive than recovering from the damaging effects to our water supplies as a result of a catastrophic wildfire made more intense as a result of poor forest management.

Natural infrastructure can safeguard and complement traditional water infrastructure systems, for example, by avoiding water pollution that would otherwise need to pass through a conventional water treatment plant, thus reducing costs. Forest management and natural infrastructure can provide many of the same services as built infrastructure, including the ability to purify water, control water temperature, minimize sedimentation, regulate urban storm water runoff, reduce the impact of floods, and hold and slowly release water into and from groundwater aquifers.

For example, during dry periods, Bozeman’s forests and floodplains continue to slowly release cool, shallow groundwater into streams. These same areas also reduce soil erosion, and store water, thereby reducing downstream flooding during heavy storms. Natural infrastructure can be adapted to manage future conditions because it tends to be more flexible and reversible than built infrastructure. Once large infrastructure is built, it is often difficult to reverse, remove or adapt for economic or social reasons. The value of natural infrastructure, on the other hand, can appreciate over time as ecosystems become more mature and potentially more resilient. Where built infrastructure exists, natural infrastructure can enhance, protect, or increase its useful life by, for example, retaining sediment.

Protecting Bozeman’s watershed can also have considerable benefits including wonderful recreational opportunities for Bozeman residents and visitors. Thanks to their close proximity to Bozeman, Hyalite and Sourdough drainages are visited by hundreds of recreationists who hike, bike, ski and ice climb. Campers and anglers consistently use Hyalite Reservoir.  Combined with other popular venues, the areas help make the Gallatin National Forest the busiest in the state for recreation.

Times have changed and Bozeman’s water challenges require a re-evaluation of current conditions and an evaluation of future needs. Preserving and managing our forests will help sustain water supplies and water quality from the city’s headwaters in the future. But, it is a community effort. Tapping our watershed councils and citizen groups to coordinate with the City of Bozeman and Gallatin County to get more people involved in water, stream and land management issues at a local level will increase opportunities for all views to be considered and conflicts avoided to sustain our water supplies.  

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