Learn about the Resilient St. Vrain Project in the 3-minute overview video.
Resilient St. Vrain is Longmont’s extensive, multi-year project to fully restore the St. Vrain Greenway and improve the St. Vrain Creek channel to protect people, property and infrastructure from future flood risk. The project, sometimes referred to as RSV or RSVP, was developed after Longmont experienced catastrophic flooding in September 2013.
The project is divided into work areas called reaches. It began at the downstream end of the St. Vrain Creek (at Sandstone Ranch) in 2016 and will take many years to complete, including time for vegetation to take hold and grow. Visit the Areas of Work & Schedule page for more information on current and future reaches as well as the reaches that have already been completed.
The flood impacted hundreds of residents throughout the City, destroying personal property, businesses and public spaces, and caused extensive damage to much of the City’s infrastructure.
It also impacted segments of the Longmont population who face various barriers impeding equal access to information, whether that is language, social network gaps, media communication, basic needs and more. In 2016, the City of Longmont started Resiliency for All, a program designed to identify those barriers, develop recommendations that would be more inclusive of the community and create space for representation from the underserved portion of the community.
Goals of the Project
- Fully restore the St. Vrain Greenway, which was extensively damaged by flooding. This involves reconstructing several sections of the greenway as construction moves upstream.
- Protect people and property (including both public and private infrastructure) by making the St. Vrain Creek through Longmont more resilient to future flood risk. Longmont is working to build community resilience to all types of disasters >
Ultimately, the St. Vrain Creek through the city will be able to safely convey up to 100-year flood flows by reducing the size of the floodplain. These improvements will also help protect our community against more likely flood flows, such as 5-, 10-, or 25-year levels.
Find out whether your property is at risk for flooding by checking the Floodplain Inquiry Map >
- Incorporate environmentally sensitive planning into the project, including:
- Maintaining and enhancing the natural habitat for wildlife and fish
- Creating wetland areas to help clean water that makes its way into the creek, and
- Incorporating natural channel design techniques such as using natural materials like rocks and plantings to create habitat and stabilize creek banks.
Learn more about Longmont’s environmentally sensitive planning efforts >
- Honor previous planning efforts in the project’s design. Many existing plans and codes influenced the project design >
Construction on this very large project is taking place in phases over several years beginning on the downstream end. Learn about the phases and anticipated timeline >
Design Process
A large-scale project such as Resilient St. Vrain requires a great deal of organization, planning and design work even before the first shovel breaks ground. Longmont began working on designs for Resilient St. Vrain in 2014.
The preliminary design phase involved environmental permitting and other planning tasks, including ensuring the design plans incorporated the master plans already in place. These activities consider all potential options to select ones that will best meet the project goals.
An overview of the plans is created and reviewed, and changes are incorporated into the preliminary design. A very large project like Resilient St. Vrain has preliminary design documents for each phase of the planned work.
The final design plans provide most details needed for construction and landscaping to occur. At that point, a contractor is selected and construction work begins using the design plans. Extensive projects like Resilient St. Vrain have a Final Design plan for each phase of work planned.
Areas of Work & Schedule
The Resilient St. Vrain project is divided into work areas called reaches. AÂ reach is an engineering term used to describe a particular section of river or creek.
Construction on this very large project is taking place in phases. It began at the downstream end of the St. Vrain Creek (at Sandstone Ranch) in 2016. The work will take many years to fully complete, including time for vegetation to take hold and grow. All construction dates and costs are estimated and subject to change as the project progresses. View funding and estimated construction dates for reaches >
Current Reaches
The City Reach follows the St. Vrain Creek through urban, developed areas of Longmont. Construction work here is:
- Restoring the flood-damaged St. Vrain Greenway
- Protecting people, property and infrastructure by improving the creek channel
- Reducing future flood risks by shrinking the size of the floodplain
- Being completed in an environmentally responsible manner
Boston Avenue Bridge
UNDER CONSTRUCTION
- Contract was awarded in May 2023
- Construction began in the summer of 2023 and is expected to last 24 months and be completed in the summer of 2025
Future Reaches
Hover Road Reach (Sunset Street to Hover Road)
- This work includes a split-flow channel through Fairgrounds Park and a new box culvert/bridge under Hover Road
- City of Longmont voters approved $20 million in Storm Drainage Bonds in 2022
- The City is awaiting grant application prior to the issuance of the bonds
- Designs have been completed. This work will commence when bonds are issued. It is expected to take approximately 18-24 months.
Channel improvements on Izaak Walton Reach 2: Boston Avenue to Sunset Street
FINAL DESIGN
Longmont has entered into a Public Partnership Agreement with the U.S. Army Corps of Engineers for final design and construction of Izaak Walton Reach 2. This phase includes channel improvements between Boston Avenue and Sunset Street. Learn more about the USACE process >
- Channel improvements between Boston Avenue and Sunset Street including a levee between Izaak Walton Pond and the creek. Final design and construction of this phase of the project will be managed by the U.S. Army Corps of Engineers.
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- Final Design is complete.
- Land acquisition and floodplain permitting is pending
- Construction is expected to start in fall 2023 and is expected to last approximately 18 months to be finished in summer 2025.
- Sunset Street Bridge has been replaced.
- Once work has been completed in this reach, the floodplain to the north of the St. Vrain Creek will be mitigated protecting lower downtown from future flood risk.
Hover Road upstream to Airport Road
CURRENTLY UNFUNDED
- Completing work through Roger’s Grove/Hover Road would achieve the Resilient St. Vrain project’s goal of removing the majority of the developed portions of Longmont downstream (west) of Hover from the 100-year floodplain.
- Final design work on these areas has not yet begun, and funding has not yet been secured.
- Creek crossings at Hover Street and Airport Road are in this reach.
Completed Reaches
Izaak Walton Reach 1: Upstream of BNSF Railroad Bridge (Price Road) to Boston Avenue
COMPLETED in 2022
- A sanitary sewer pipe that crosses the St. Vrain Creek upstream of the Boston Avenue Bridge was relocated.
- Modular block walls were installed in this reach.
- This is the shortest reach within the Resilient St. Vrain project.
LOMR #1
RECEIVED FEDERAL APPROVAL
The new floodplain maps (Preliminary FIRMs) have been updated with the projects listed below that have been completed along the St. Vrain Creek.
The first Letter of Map Revision (LOMR #1) to the Preliminary FIRMs include the updates for the completion of:
- Sandstone Ranch Reach
- County Line Road Bridge
- City Reach 1, including Dickens Farm Nature Area and Boston Avenue
- Main Street Bridge
- South Pratt Parkway Bridge
- City Reach 2A, Main Street to Colorado Way (just west of S. Pratt Parkway)
As shown in the figure below, LOMR #1 begins to remove property downstream of BNSF railroad and south of the creek from the 100-year floodplain. Click on the map image to open a PDF version that can be viewed larger or downloaded.
Map key:
- Blue (Preliminary FIRM and 2012 Effective) represents the 100-year floodplain.
- Black crosshatch area represents the property removed from the 100-year floodplain with LOMR #1.
The LOMR #1 final report is available for viewing and download at this link. The complete RSVP LOMR #1 report, including appendixes, large computer model and GIS files, is available by request from Longmont’s Floodplain Administrator.
City Reach 2B: West of South Pratt Parkway to BNSF Railroad Bridge (Price Road)
COMPLETED 2021
- BNSF Railroad Bridge has been replaced as part of an agreement between Longmont and BNSF.
- The St. Vrain Creek channel was improved to help protect the community from future flood risks.
- Modular block walls were added in this reach.
- The contractor completing fencing, irrigation and landscape planting in this area.
City Reach 2A: Main Street to just west of South Pratt Parkway
COMPLETED FALL 2019
- This reach includes a wider creek channel between Main Street and South Pratt Parkway.
- Modular block walls are being installed in the tighter urban corridor west of South Pratt Parkway.
- Over 150,000 native plants will be added, along with over 30,000 square feet of wetland sod and nearly 10 acres of seeding. View a list of species planted through the Resilient St. Vrain Project >
- South Pratt Parkway Bridge has been replaced.
- The St. Vrain Greenway is fully open from South Pratt Parkway east to Sandstone Ranch.
City Reach 1: Left Hand Creek confluence (east of Martin Street) to Main Street
COMPLETED SUMMER 2018
- Main Street Bridge has been replaced.
- Dickens Farm Nature Area has been completed and is now open.
Sandstone Reach
COMPLETED SPRING 2018
Sandstone Reach follows the St. Vrain Creek through the Sandstone Ranch Nature Area and surrounding open space. Construction began in November 2016 and continued through spring 2018.
Goals of work in this area were to:
- restore the flood-damaged St. Vrain Greenway. The trail is now fully open though this area
- stabilize creek banks to protect trails, access roads and infrastructure from future flood damage
- help nature re-establish vegetation and wetlands habitat for fish and wildlife. Nearly 200,000 native plants were added. View a list of species planted through the Resilient St. Vrain Project >
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Restore & Revitalize
Conveying 100-Year Flood Flows
The term 100-year flood refers to an event that has a 1 percent chance (or 1 in 100 probability) of occurring each year; however, 100-year floods can happen much more often than once every 100 years, as flooding events are irregular and depend on many factors. The 100-year floodplain is the area covered by water during a 100-year flood. The Federal Emergency Management Agency (FEMA) refers to the 100-year floodplain as the Special Hazard Flood Area (SHFA).
View a U.S. Geological Survey poster that explains what “100-year flood” means (1 MB PDF)
Design plans for Resilient St. Vrain use the estimated 100-year flood flows and the 100-year floodplain as benchmarks. FEMA, state and local agencies use the 100-year floodplain in regulatory processes related to floodplain development, building permits and environmental regulations, as well as for setting flood insurance requirements and costs.
Resilient St. Vrain designs include a wider creek channel and bridges to safely convey the estimated 100-year flood flows, which in turn will reduce the size of the 100-year floodplain. This reduction means that fewer properties ultimately will be located within the floodplain.
Flood insurance is only required for properties in the 100-year floodplain that have federally backed loans. Flood insurance is available to any property owner in Longmont, regardless of whether the property is located in the 100-year floodplain. However, flood insurance is much less expensive for properties mapped outside the 100-year floodplain.
View maps and information about proposed revisions to the floodplain >
(For comparison, a 500-year flood event has a 0.2% chance of occurring each year. Resilient St. Vrain does not use the estimated 500-year flood figures as a standard because neither FEMA nor the state regulate the 500-year floodplain.)
Learn more about Resilient St. Vrain project goals and design.
St. Vrain Floodplain Updates
Are you in a floodplain? Find out using Longmont’s Floodplain Inquiry Map.
The Federal Emergency Management Agency (FEMA) approves the Flood Insurance Rate Maps (FIRM) for communities. The FIRM shows the area of land that could be inundated by a 100-year flood event, known as the Special Flood Hazard Area (SFHA). The SFHA has a 1% chance of flooding in any given year. These maps are also used to rate flood insurance.
The map below overlays the new existing 100-year floodplain areas (shown in red) over the 2012 FEMA FIRMs (shown in blue). The new, existing 100-year floodplain has been submitted to the state (as part of CHAMP) for incorporation into the new FEMA FIRMs, which are planned to be effective in early 2019.
Click on any map to open a PDF file that can be enlarged for easier viewing or saved to your computer. Have questions about these maps and what they mean for your property? Please contact the City of Longmont Floodplain Administrator.
View draft floodplain maps for the unincorporated Boulder County areas west of Longmont >
Learn more about why work on Resilient St. Vrain is being built to 100-year flood flow levels >
CLOMR / LOMR Process
Revisions to the floodplain map through a Conditional Letter of Map Revision (CLOMR) are being proposed for Sandstone Reach and City Reach 1. The City of Longmont is in the process of notifying property owners of ongoing and upcoming projects that may affect flood elevations along and near St. Vrain Creek.
The maps on this page present three Special Flood Hazard Area (SFHA) stages for the first two Resilient St. Vrain work areas (Sandstone Reach and City Reach 1). Click on any of the maps below to open a larger PDF file that can be downloaded to your computer or enlarged for easier viewing.
Sandstone Reach
Sandstone Reach follows St. Vrain Creek from County Line Road downstream (eastward) approximately 2.5 miles to the Boulder Creek confluence (point where the two creeks meet) near Highway 119.
Regulatory Floodplain
In 2015, FEMA approved updated Flood Insurance Rate Maps (FIRM) for Weld County. These maps show the 100-year flood risk and are used to rate flood insurance policies. The map below, referred to as the “regulatory floodplain,” shows the Special Flood Hazard Area (SFHA) boundaries within the Sandstone Reach.
Existing Conditions Floodplain
After the 2013 flood, the Colorado Department of Transportation (CDOT) and Colorado Water Conservation Board (CWCB) conducted a hydrology study of the watershed to evaluate flood flow rates. CWCB is currently working with FEMA to update the FIRM to reflect the results of the new flow rates; that work is expected to be completed sometime in 2018. The map below reflects the new approved 100-year flood flow rates, as well as the post-flood topography along the creek corridor. The floodplain boundaries shown in this map of the Sandstone Reach are referred to as the “existing conditions.”
Proposed Conditions Floodplain
After work to repair the flood damage is completed through the Resilient St. Vrain project, the City of Longmont will submit floodplain revisions to FEMA. Those planned revisions, referred to as the “proposed conditions” floodplain, are shown in the map of the Sandstone Reach below.
City Reach 1
City Reach 1 follows the St. Vrain Creek from slightly west of Main Street downstream to the confluence (point where the two creeks meet) with Left Hand Creek, east of Martin Street.
Regulatory Floodplain
In 2012, FEMA approved updated Flood Insurance Rate Maps (FIRM) for Boulder County. These maps show the 100-year flood risks and are used to rate flood insurance policies. The map below, referred to as the “regulatory floodplain,” shows the Special Flood Hazard Area (SFHA) boundaries within City Reach 1.
Existing Conditions Floodplain
After the 2013 flood, the Colorado Department of Transportation (CDOT) and the Colorado Water Conservation Board (CWCB) conducted a hydrology study of the watershed to evaluate flood flow rates. CWCB is currently working with FEMA to update the FIRM to reflect the results of the new flow rates; that work is expected to be completed sometime in 2018. The map below reflects the new approved 100-year flood flow rates approved from the CDOT study, as well as the post-flood topography along the creek corridor. The floodplain boundaries shown in this map of City Reach 1 are referred to as the “existing conditions.”
Proposed Conditions Floodplain
After work to repair the flood damage and improvements to the creek channel to pass the new 100-year flood flow rates are completed through the Resilient St. Vrain project, the City of Longmont will submit floodplain revisions to FEMA. Those planned revisions are referred to as the “proposed conditions” floodplain
For City Reach 1 “proposed conditions” in the map below, two floodplain areas are shown. The green and purple areas together comprise an interim condition, while the purple area on its own is an estimate of the 100-year floodplain after additional improvements are completed upstream of City Reach 1.
For More Information
The Colorado Hazard Mapping Program (CHAMP) is remapping the 100-year floodplain of creeks affected in 2013, including the St. Vrain Creek. Read about the St. Vrain Watershed Risk Mapping Assessment and Planning effort >
Floodplain map changes such as the ones detailed above can affect flood insurance premiums. Learn more in this FEMA brochure >
The National Flood Insurance Program maintains a website, FloodSmart.gov, to share information about flood risks.
For questions about the regulatory, existing, and proposed condition floodplain areas, contact the City of Longmont Floodplain Administrator.
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Resilience
Spotlight
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Resiliencia Para Todos / Resiliency for All has completed its Report to the Community and created a video identifying the barriers to resiliency that exist in Longmont.
Please visit the main page for Resiliencia Para Todos | Resiliency for All for more information.
The concept of resilience has become popular recently, and definitions for the term vary. However, the concept incorporates the recognition that disasters or other impactful events–such as the September 2013 flooding in Longmont–will happen, and that how communities prepare for and react to those events can make a difference. The ability to react to and incorporate ways to more easily bounce back from the next time something bad happens is a critical component of resilience.
Be Prepared
Preparation for a future event, such as flooding, can include preparing and protecting people, property and the environment, as well as creating plans that can be implemented at the first sign of a disaster event.
- Know how to stay connected in case of emergencies like flooding with Flood Preparedness & Safety tips from Longmont’s Office of Emergency Management.
- Prepare for threats from flooding with recommendations from FEMA Region VIII, which includes Colorado.
- Explore getting involved with Longmont CERT, the Community Emergency Response Team, which helps you prepare yourself, your family, and your neighbors in case of an emergency.
- Attend a class offered by BeReady Longmont or invite this outreach program to present to your community group, neighborhood or workplace.
- Consider purchasing and maintaining flood insurance for your property, which can be an important component of your preparedness plan.
- Learn about why work on the Resilient St. Vrain flood mitigation project is being built to safely convey up to 100-year flood flows.
Learn More
These organizations focus on building resilience on the local, state and national level. Follow the links below to visit their websites and learn ways to get involved or apply resilience concepts.
BoCo Strong
BoCo Strong was created with the purpose of building a culture of resilience throughout Boulder County. It formed in the wake of the 2013 flood. Its community-powered resilience network strives to be inclusive and work all across the county for continued resilience, not just after a disaster.
Resiliencia para Todos / Resiliency for All
Resiliencia para Todos / Resiliency for All (RFA) is a City of Longmont collaboration with local municipalities and BoCo Strong. The project comes in the aftermath of the 2013 flooding throughout Boulder County. RFA works to identify barriers and create a bridge between a vulnerable Latino population, community resources, and local governments. Learn about the group’s work and view a timeline of its activities (PDF).
Boulder County Collaborative
The City of Longmont is the lead agency for the Boulder County Collaborative, a group of local municipal and county governments that formed in response to the 2013 floods to decide together where to strategically direct federal CDBG disaster recovery funds to best address the greatest and most pressing housing and infrastructure needs. The Collaborative created the Resilient Design Performance Standard for Infrastructure and Dependent Facilities to guide the design and implementation of recovery projects in the region. This standard leverages every capital project as an opportunity to incrementally move Boulder County toward a more resilient future.
Mile High United Way
The goal of Mile High United Way is to build a more resilient community by connecting strong resources with each other and developing a system that responds to community shocks and stressors effectively and efficiently.
St. Vrain Creek Coalition
St. Vrain Creek Coalition works to implement to the St. Vrain Creek Master Plan and pursue recovery from flood impacts, resiliency to natural hazards, and protection of the watershed.
The Watershed Center
The Watershed Center serves the community by monitoring, protecting and restoring the Left Hand Creek Watershed.
Colorado Resiliency Office
The Colorado Resiliency Office is the official State of Colorado website for resiliency and recovery information and resources.
- The Colorado Resiliency Office is a statewide group of communities, counties and partners working to share lessons learned from recent floods and fires and to find ways to improve disaster response and preparedness throughout the state.
- Read more about how communities are becoming more resilient in the Colorado Resiliency Framework plan (updated in 2020)
Community & Regional Resilience Institute
The goal of the Community and Regional Resilience Institute (CARRI) is to strengthen any community or region’s ability to prepare for, respond to, and rapidly recover from significant human caused or natural disaster with minimal downtime for the community. Read CARRI’s report on Community Resilience.
Click the funding graphic above to open a PDF file that can be downloaded to your computer or enlarged for easier viewing.
Construction on this very large project is taking place in phases beginning on the downstream end. Learn about the project phases, known as reaches. All construction dates and costs are estimated and subject to change as the project moves forward.
Project Costs
The cost for work on the Resilient St. Vrain Project has been estimated between $120 million and $140 million. Note that this amount is not the City’s portion of the cost, as it includes federal, state and other funding sources. Generally, for every dollar of cost, 75 cents is paid for by federal sources, with the remaining 25 cents divided between state and local sources.
Project Funding
Partial project funding is coming from a variety of sources, including:
- $20 million in voter-approved Storm Drainage Bonds
- Federal Emergency Management Agency (FEMA)
- Community Development Block Grant-Disaster Recovery (CDBG-DR)
- Great Outdoors Colorado (GOCO)
- State and County funds
- Other existing City funds, including the 3/4-cent Street Fund sales and use tax permanently extended by voters in 2019.
The City of Longmont continues to actively seek grants and other financial partners to help fully fund the project. One of these partners is the U.S. Army Corps of Engineers. Learn more about the U.S. Army Corps of Engineers’ feasibility study to complete a portion of the Resilient St. Vrain Project.
U.S. Army Corps of Engineers
Feasibility Report and Environmental Assessment
Overview
In early 2017, the U.S. Army Corps of Engineers (USACE) began a feasibility study of the section of the St. Vrain Creek running from the BNSF railroad bridge to Lykins Gulch. The feasibility study built upon the existing work done through the Resilient St. Vrain Project.
The purpose of the Corps’ analysis was to locate an area within the study section that could possibly qualify for an approximately $15 million project as part of the USACE’s 205 program.
The local agency (in this case, Longmont) is required to provide a minimum funding match of 35 percent (approximately $5 million). The City’s local match share for the USACE project will consist of
- approximately $750,000 in funds for final design and construction;
- credit for the City-owned land and right-of-way along the St. Vrain Creek that will be used for the project and acquisition of additional land and easements required for the project; and
- replacement of the Boston Avenue Bridge over St. Vrain Creek.
Section 205 of the Flood Control Act of 1948 allows the USACE to construct or improve site-specific flood risk management projects. The Section 205 Program is different from other federal funding sources, such as FEMA and HUD, that Longmont has obtained for previous phases of the RSVP.
Under the Section 205 Program, the USACE will manage final design and construction of its portion of the project, which includes the channel improvements and a levee along the north bank of St. Vrain Creek adjacent to Izaak Walton Pond. The City will manage final design and construction of the Boston Avenue Bridge over St. Vrain Creek project. The City will be responsible for operation, maintenance and repair of the project improvements upon completion of the project.
In August 2019, the USACE released its draft report and Environmental Assessment (EA) on options for work in the area upstream of the BNSF railroad bridge to Hover Road. That draft was available for public comment through Oct. 4, 2019.
At its Aug. 11, 2020, meeting, the Longmont City Council approved a negotiated Public Partnership Agreement with the USACE for final design and construction of the preferred/recommended design option, which is Izaak Walton Reach 2 and replacement of the Boston Avenue Bridge over St. Vrain Creek. Longmont’s contribution will be made through credit for cash contribution and the replacement of the Boston Avenue Bridge over St. Vrain Creek, and land ownership.
The Final Feasibility Report and Environmental Assessment was released in October 2020. That report is available for viewing and download on the USACE’s project webpage.
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Environmentally Responsible Planning
This includes:
- Maintaining or enhancing the natural habitat for wildlife and fish
- Creating wetland areas to help clean water that makes its way into the creek after storms or by runoff from more developed areas
Environmental Assessment
After the September 2013 flood, an emergency declaration by the Federal Emergency Management Agency (FEMA) allowed the City to obtain public assistance grant funding to construct parts of the Resilient St. Vrain Project. The project went through an environmental review process as part of the grant requirements.
The grant required that the project go through an environmental review process established by the National Environmental Policy Act (NEPA). This review process ensures planning and decision-making gives equal consideration to environmental factors (such as physical, biological, social and cultural), as well as financial and technical factors.
The public review and comment period was from March 30 to April 29, 2016.
FEMA has issued a Finding of No Significant Impact (FONSI) on the Environmental Assessment (EA) that was submitted for the Resilient St. Vrain project.
Full copies of the FONSI and the Final Environmental Assessment (FEA), including all appendices, are provided below.
*Para información en Español llame al 303-651-8416.
- EA Appendices
- Final Environmental Assessment for the Resilient St. Vrain Project
- Finding of No Significant Impact (FONSI) for Resilient St. Vrain Project
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St. Vrain Greenway
The St. Vrain Greenway is being reconstructed and rebuilt all along the St. Vrain Creek.
- The St. Vrain Greenway is fully open from Sandstone Ranch Nature Area west to Main Street
- Temporary trail closures or detours will be required as project construction moves upstream. Consult the Trail Status Map for details
Trees, Grasses and Vegetation
Learn more about trees along the St. Vrain Creek and their role in a healthy ecosystem >
- Some trees are being removed for construction
- Native-species trees, shrubs, and grasses are being planted to maintain and enhance natural wildlife habitat areas along the creek. View a list of species planted through the Resilient St. Vrain Project >
- Contributions are being made to the City fund that allows for planting as needed elsewhere within Longmont’s Urban Forest. These contributions are especially useful with the 2016 discovery of Emerald Ash Borer in Longmont
- Project Payments to City Tree Fund
- City Reach 1 $195,333
- City Reach 2A $487,600
- City Reach 2B $218,100
- Izaak Walton Reach 1 $152.850
- Izaak Walton Reach 2 TBD
- Plantings will provide refuge areas for wildlife, birds and fish along the creek, while also considering public safety and the safe conveyance of flood flows
Wildlife
Resilient St. Vrain focuses on the area surrounding the creek, known as the creek corridor. Improving the corridor will create and enhance habitat areas for wildlife, including fish and birds.
The project team works closely with federal and state agencies to ensure work times are sensitive to the nesting cycle of bald eagles and other wildlife.
Natural Channel Design
Construction on Resilient St. Vrain incorporates many components of natural channel design, including:
- Respecting the creek’s natural tendencies to curve and meander over time and allowing space for this to happen
- Using natural materials (such as tree roots and logs, rocks, and vegetation) to enhance habitat and stabilize creek banks
Sandstone Ranch
The St. Vrain Creek remains in its post-flood alignment in the Sandstone Ranch Nature Area. This allows the creek to use a larger, more natural floodplain. Work in Sandstone focused on stabilizing creek banks and beds, while also giving nature a jump-start through seeding and plantings.
- Nearly 200,000 new plants were placed in this area. View a list of species planted through the Resilient St. Vrain Project >
- Fish studies conducted by Colorado Parks and Wildlife show that native fish populations have established themselves in the area’s post-flood creek channel,
Trees play an essential role in our community, helping to improve air quality and reduce the effects of pollution, as well as providing habitat for wildlife and contributing to a more aesthetically pleasing cityscape.
As an important piece of a healthy ecosystem, trees are one component of the overall Resilient St. Vrain project goal of completing the work in an environmentally sensitive manner. The project includes removal of a variety of trees, including native Cottonwoods damaged in the September 2013 floods and non-native or invasive tree varieties, such as Russian olive. Additional trees are slated for removal to allow for healthy tree spacing and to create the capacity necessary to safely convey 100-year flood flows throughout Longmont.
Tree Spacing
Tree spacing plays a critical role in the resilience of the creek channel. In the September 2013 floods, debris built up against densely packed trees in along the St. Vrain Creek, creating walls of debris that slowed down stormwaters.
Appropriate tree spacing allows water to flow around the trees, even as debris may pile up in front of trees. This healthy spacing can prevent blockages along the creek, while continuing to provide areas for wildlife to move along the corridor.
Protecting Wildlife Habitat
A variety of wildlife, including protected native birds and fish, live in and around the St. Vrain Creek. Monitoring and protection of this wildlife is ongoing throughout Resilient St. Vrain construction.
Wildlife biology experts, including Colorado Parks and Wildlife, help evaluate trees along the St. Vrain Creek channel for avian nests and other crucial habitat factors, and project contractors receive environmental awareness training. Additionally, safety buffers and work timelines have been implemented to ensure wildlife protection throughout the work areas.
Replanting Trees, Shrubs and Grasses
New, native vegetation will be planted along the St. Vrain Creek as construction is completed in each section. As shown in the sample progression images on this page, vegetation will not be replanted exactly as it was prior to construction. Plantings will provide refuge areas for wildlife, birds and fish along the creek, while also considering public safety and the safe conveyance of flood flows. View a list of species planted through the Resilient St. Vrain Project.
Work on the Resilient St. Vrain project complies with Longmont’s municipal code ordinances related to Forestry. Generally, this code requires replanting equivalent quantities of quality trees or contributing to a City fund that allows for planting as needed elsewhere within Longmont’s urban forest. These fund contributions have been especially helpful after the 2016 discovery of Emerald Ash Borer within Longmont.
Looking to the Future
Throughout the design process for Resilient St. Vrain, careful consideration has been given to ensuring that healthy trees are a part of the St. Vrain Creek ecosystem. The images below show illustrations of two areas along the St. Vrain Creek.
- The first image in each group (“Current”) shows a current view of the area (post-flood and pre-construction)
- The middle image (“Post-Construction”) illustrates how the area is anticipated to look once construction work is finished, landscaping has occurred, and the newly seeded areas are established
- The final image (“Mature Vegetation”) illustrates how the area is projected to look once trees and other vegetation reach maturity (approximately 15-20 years after construction)
The first three images are for the area from Main Street looking west to South Pratt Parkway. Click on an image to open a larger version.
Main Street to South Pratt Parkway (looking west): Pre-Construction
Main Street to South Pratt Parkway (looking west): Post-Construction
Main Street to South Pratt Parkway (looking west): Mature Vegetation
The three images below show the same progression in the area from South Pratt Parkway looking west to the BNSF railroad bridge (near Price Road). Click on an image to open a larger version.
South Pratt Parkway to BNSF railroad bridge (looking west): Pre-Construction
South Pratt Parkway to BNSF railroad bridge (looking west): Post-Construction
South Pratt Parkway to BNSF railroad bridge (looking west): Mature Vegetation
Looking to the Past
The St. Vrain Creek is constantly evolving. Historical images show a vastly different creek area, with significantly fewer trees along its bank, than prior to the 2013 flood.
As part of its collection, the Longmont Museum has several historical images of the St. Vrain Creek. View Longmont Museum images.
Plans, Maps & Reports
Maps
St. Vrain Greenway Trail Detour Map
Rendering of Resilient St. Vrain Reach Areas
Phasing Map Showing Current Status and Construction Timelines for Each Reach Area [PDF]
Longmont Floodplain Inquiry Map (webpage link)
Boulder County floodplain maps (including draft updates)
Reports
Final Environmental Assessment (EA) and Finding of No Significant Impact (FONSI) for RSVP
LOMR #1 Final Package
The LOMR #1 final report is available for viewing and download at the link below. The complete RSVP LOMR #1 report, including appendixes, large computer model and GIS files, is available by request from Longmont’s Floodplain Administrator.
RSVP City Reach 3 Conceptual Design Options Technical Memo
Note: This very large document has been broken into several parts. Each PDF below may be opened for viewing or download.
COL Staff Cover Memo for RSVP City Reach 3 Conceptual Design Options Technical Memo
RSVP City Reach 3 Conceptual Design Options Technical Memo
Attachment A: 2015 Alternative Analysis Figures
Attachment B: Conceptual Design Options Figures
Attachment C: Engineer’s Opinion of Probable Costs and Attachment D: DVD of Referred Documents
U.S. Army Corps of Engineers Feasibility Study
Draft Report and Environmental Assessment (September 2019) External link to USACE website
Guiding Plans and Codes
Various plans and codes act as guides to how the City will approach growth, development or preservation in a specified area or on a certain project. These guidelines are only adopted by the City after much research and public input. The following plans and codes influence the Resilient St. Vrain project:
1st and Main Transit and Revitalization Plan
Dickens Farm Nature Area Master Plan
Parks, Recreation and Trails Master Plan
St. Vrain Greenway Master Plan
Other Materials
From Recovery to Resilience informational sign (posted along St. Vrain Greenway)
Funding and Construction Status
Free viewers are required for some of the attached documents.
They can be downloaded by clicking on the icons below.
St. Vrain Greenway Trail Detour
St. Vrain Greenway Trail closures have been moving steadily westward with progress on the Resilient St. Vrain project. Currently, the trail is closed from South Sunset Street on the western end to Price Road on the eastern end and is clearly marked with signs to safely route pedestrians and bicyclists around the work zone. Click here to open a PDF of the detour route that can be downloaded or printed for reference
Recreational Use of St. Vrain Creek
The St. Vrain Creek is open to public use downstream of Main Street, as part of the Dickens Farm Nature Area. Signs mark a designated open water access point at Main Street and takeout points east of Martin Street and at the 119th Street trailhead. Remember that any time you enter the creek, it is at your own risk. Learn more about guidelines for recreational use of St. Vrain Creek.
