2017-2024 Erosion Rates Along Fountain Creek

In 2017, the Fountain Creek Watershed District partnered with other collaborators to conduct the Fountain Creek Corridor Watershed Assessment of River Stability and Sediment Supply (WARSSS) study. At that time, the erosion rate and potential for future water erosion were used to guide decision making and funding of Fountain Creek Watershed District (FCWD) projects at sites determined to have high priority. This StoryMap looks at how Fountain Creek erosion has changed since the 2017 report and assesses the success of three FCWD bank stabilization and erosion control projects.

• Assess the success of three FCWD projects focused on increasing erosion control and bank stabilization.
• Compare major similarities and differences between areas of high erosion identified in the 2017 WARSSS study and 2018-2024 satellite imagery data.

• Fountain Creek is a dynamic river that is always changing. 
• Previous Fountain Creek projects are meeting project goals to effectively control erosion rates. 
• Areas where restoration work has not been completed continue to experience a range of instability. 
• As work continues on Fountain Creek, it is critical that the river be studied and improved as a dynamic system that is constantly changing and evolving.

To better understand the efficacy of these projects on mitigating and reducing erosion rate, we focus on three projects completed at sites identified as "high priority" by the 2017 WARSSS report. These are the Masciantonio Trust Bank Restoration (completed April 2018), the Pinon Bridge Bank Stabilization Project (completed Spring 2019), and the Highway 47 Bank Restoration Project (completed November 2018).

We assess and present aerial photos of the restoration sites from 2018 and 2024. These aerial views allow us to compare the relative stability of these sites since their respective projects completion.

The selected sites provide case study and visualization for how all project sites may be responding to restoration work aimed at increasing erosion control.

• Total Cost: 2.0 million 
• Problem: Lateral channel erosion caused excessive bank erosion causing a loss in agricultural land 
• Project Goals: Improve bank stability, reduce sediment loading, protect agricultural properties 

As shown in the image from the 2017 WARSSS report to the right, the goal of the Masciantonio Trust Bank Stabilization Project was to stabilize the curve of the river on the western bank of Fountain Creek indicated by the red line. In the sliding image above, we see this curve established and reinforced by the project in the same place in the 2018 aerial imagery (green) and the 2024 arial imagery (blue). For this reason, we conclude that the project has successfully stabilized the bank and prevented major erosion since its completion.

Further, our arial investigation did not find any significant erosion of the bank directly above or below the project's high priority area. This means that this section of Fountain Creek is stable and poses minimal risk of significant sediment being added to Fountain Creek in a future flooding event.

Upstream of the Masciantonio Trust project site (pink arrow in figure left), where no restoration project work has been completed (purple arrows in figure left), we see a section of Fountain Creek that remains highly unstable. The 2024 channel path, shown as the bright red line in the image to the left, has migrated significantly from its position in 2018, shown as the darker red line in the image. Additionally, the active area of the channel has widened significantly in some areas between 2018 (in green), and 2024 (in blue). This migrating channel is directly correlated with increased sediment being swept downstream and undermines the success of the Masciantonio Trust Bank Restoration Project. While we can't conclude that work at the Masciantonio Site caused an increase in upstream erosion. This observation reinforces the highly interdependent nature of channel erosion and the need to continue to study, monitor, and complete further work in Fountain Creek. Future projects that aim to stabilize Fountain Creek in the region upstream of the Masciantonio Trust site would decrease the sediment load of the creek as it runs through the area, helping mitigate the effects of this issue.

• Total Cost: 2.3 million
• Problem: Flood flows caused increased lateral erosion/widening, putting the bridge at risk
• Project Goal: Creek realignment to enhance sediment transport to promote long-term channel stability.

As shown in the image from the 2017 WARSSS report to the left, the goal of the Pinon Bridge Bank Stabilization Project was to reinforce the bank identified by the red line on Fountain Creek's western bank in order to ensure the water flows perpendicular to the bridge rather than at an angle. In the sliding image above, we can see that in 2024 (shown in blue), Fountain Creek flows much more perpendicularly to Pinon Bridge and that the western bank now has a much more defined and stable curve. For this reason, we consider the project successful. At the Pinon Bridge site, Fountain Creek is now in a much more stabilized position. This stabilization is especially noticeable directly alongside and under Pinon Bridge, where channel width greatly decreases, indicating realignment of channel banks.

Similar to the Masciantonio Trust site, an area upstream of Pinon Bridge remains widely unstable which threatens the success of the downstream project. In the image to the right, the channel position each year from 2018-2024 is outlined in a different color. At downstream locations near the restoration project (pink arrows), the channel remains consistently in the same position. However, just upstream of this site (blue arrow), the bank position has varied widely from year to year. Widening and inconsistent channel positions present an erosion concern that could impact the stability of infrastructure at the bridge downstream and effects of the FCWD project. Further study and restoration in this upstream area will be advantageous to meeting the districts goals and reducing the erosion rate of Fountain Creek.

• Total Cost: 6.0 million
• Problem: Large scale lateral erosion directly upstream of State Hwy 47 creating a high risk to the bridge.
• Project Goal: Stabilization of Fountain Creek including downstream sediment reduction and erosion protection for the Highway 47 bridge.

As shown in the image from the 2017 WARSSS report to the right, the goal of the Highway 47 Bank Restoration Project was to reduce bank erosion upstream and downstream of the bridge and to change the angle at which this sediment was transported under the bridge. In 2017, there was significant eastward migration of Fountain creek directly upstream of Highway 47. Using the slider feature, we can see the transition that in the time since the projects completion in 2018 (green) to 2024 (blue), Fountain Creek has remained stable in its relative centerline position and no eastward migration is observed. Therefore, we conclude that this project has been successful in stabilizing the floodplain of the Highway 47 and mitigated risk of decreased bridge stability from erosion. However, upstream erosion identified at sites where restoration work has not been completed still pose a risk to the surrounding infrastructure, like the Highway 47 bridge.

The 2017 WARSSS study importantly noted "that stream assessment and project work is not a static process. The prioritization will need to be updated as projects are constructed, new GIS information becomes available, and as the Fountain Creek Corridor continuously changes. Projects which have scored highly in this iteration could score lower in future iterations, and vice versa, based on changing conditions. This study has created a repeatable process that can be implemented into the future."

Fountain Creek is dynamic and will continue to change. However, through our investigation into three project sites, we see evidence of that through restoration project work, the risk of economic and environmental destruction can me minimized. At the same time, the effectiveness of one project will not reach its full potential until all of Fountain Creek can be restored. The 2024 Project Effectiveness Report from Matrix group identifies that the continued erosion from unrestored sites has the potential of negatively effecting and damaging the completed project. This Barr Farm Channel Restoration Project is one of several examples where previous restorative efforts are at risk. Therefore, the ongoing work of Fountain Creek Watershed District to obtain funding and generate community support for the completion of future projects is integral to the success of the communities that share the Fountain Creek Watershed.