Agenda Date: 10/15/2024
Subject:
Title
Resolution 112-2024: Approving an Intergovernmental Agreement (IGA) between the City of Littleton and Mile High Flood District, regarding funding of Major Drainageway Planning for the High Line Canal Stormwater Transition and Management Plan
Body
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From: |
James L. Becklenberg, City Manager |
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Prepared by: |
Sarah White, Water Resources Manager |
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Presentations: |
Brent Soderlin, Director of Public Works & Utilities |
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Sarah White, Water Resources Manager |
PURPOSE:
Does council support an Intergovernmental Agreement (IGA) with Mile High Flood District (MHFD) regarding funding of Major Drainageway Planning for the High Line Canal (HLC) Stormwater Transition and Management Plan (STAMP)?
LONG-TERM OUTCOME(S) SERVED:
Safe Community; High-Quality Governance; Sustainable Community with Natural Beauty
DISCUSSION:
Since 1883, the High Line Canal has been operated as an irrigation channel. Now over 140 years later, as the Denver metro region has developed from an agricultural area to an urban landscape, the function of the canal as an irrigation supply has diminished. The HLC and adjacent trail serve as a cherished open space and recreational resource in the metro area. The HLC is in a time of transition to a new life as a recreation and ecological resource. A unique opportunity now exists to use this asset for stormwater management.
Since 1924, the HLC has been owned and operated by Denver Water. In June 2024, Denver Water transferred 45 miles of the HLC ownership to Arapahoe County. The ownership transfer included a conservation easement to permanently protect the HLC as a natural open space.
To help direct this transition into a stormwater resource and advance discussions about future management of the Canal, the Canal Collaborative is developing the Stormwater Transition and Management Plan (STAMP). Led by MHFD, the STAMP will support local jurisdictions to make the previous studies operational. The STAMP will provide jurisdictionally specific hydrology and modeling, help define operations and maintenance approaches, identify capital improvement needs, and canal wide planning.
BACKGROUND:
The High Line Canal (HLC) was constructed in 1883 to provide irrigation water for the South Platte River and Cherry Creek valleys. The canal is 71 miles long and begins in Waterton Canyon in Douglas County and ends in Green Valley Ranch in northeast Denver. Denver Water purchased the canal in 1924 but restricted recreation uses until the 1970s, when the maintenance road was repurposed to a recreational trail. The HLC has become a valuable recreational amenity for the Denver metro area, including the 5.5 miles within the City of Littleton.
Irrigation water usage has decreased significantly, and the lack of water has negatively impacted the vegetative growth along the canal. In 2015, a Canal Collaborative was established to explore the feasibility to preserve, protect and enhance the HLC as a regional legacy for future generations. The Collaborative consists of thirteen partners: Arapahoe County, City of Aurora, City of Cherry Hills Village, City and County of Denver, Denver Water, Douglas County, City of Greenwood Village, Highlands Ranch Metro District, High Line Canal Conservancy, City of Littleton, Mile High Flood District (MHFD), Southeast Metro Stormwater Authority and South Suburban Parks and Recreation District.
The Collaborative also focused on converting the Canal to green stormwater infrastructure. Denver Water has historically limited and restricted use of stormwater being directed into the HLC. As such, any regional stormwater plans would exclude the Canal as a receiving water body. To use the Canal as a regional drainageway or green infrastructure, additional analysis needed to be done. The Canal Collaborative first looked at a high-level study, and the High Line Canal Feasibility Study for Stormwater Runoff Reduction and Treatment in was completed in August 2014. The next step was a more detailed hydraulic study, and the High Line Canal Stormwater Master Plan was completed in 2018. That study identified water sources entering the HLC and begin modeling the HLC for potential modification into a regional drainageway. There are several locations within Littleton where storm water runoff either flows under or into the canal. These feasibility studies determined it may be viable to collect and passively treat stormwater within the canal. This treated stormwater may then be used to support and sustain the current environmental and recreational uses of the canal.
Prior Actions or Discussions
In 2017, Littleton authorized funding of the High Line Canal Stormwater Master Plan (Resolution 10-2017).
In 2019, the city entered into an IGA with Denver Water to build a stormwater discharge into the canal on the west side of Windermere Street. As part of this agreement, the city agreed to take on certain maintenance responsibilities in the canal, from this location downstream to Lee Gulch (1 mile).
In 2021 and 2022, the city entered into a joint maintenance agreement, managed by MHFD, to provide such maintenance activities in the city’s 1-mile reach.
In 2023, the City of Littleton acquired additional city maintenance responsibilities, from Broadway to Broadway (containing Euclid Avenue), approximately ½ mile through an IGA amendment with Denver Water.
FISCAL IMPACTS:
The STAMP will be primarily funded by members of the Collaborative. The total anticipated cost of the plan is $657,500. The cost shares were then based on a base dollar plus jurisdictional miles, Littleton’s funding share is $37,500 (6% of total cost).
This will be paid from the 2024 Storm Drainage Enterprise Fund budget.
STAFF RECOMMENDATION:
Staff recommends approval of the Intergovernmental Agreement.
ALTERNATIVES:
Should council not approve this agreement, the City of Littleton would need to develop separate stormwater modeling plans or alternative irrigation plans which does not take advantage of cost savings associated with a joint agreement managed by the MHFD and other contributing partners.
PROPOSED MOTION:
Proposed Motion
I move to approve Resolution 112-2024 approving an Intergovernmental Agreement between the City of Littleton and Mile High Flood District, regarding funding of Major Drainageway Planning for the High Line Canal Stormwater Transition and Management Plan.