Agenda Date: 11/17/2020
Subject:
Title
Resolution 75-2020: Approving an intergovernmental agreement with Mile High Flood District regarding final design, right-of-way acquisition, and construction of drainage and flood control improvements for Jackass Gulch at Highline Canal
Body
Prepared by:
Carolyn R. Roan, Water Resource Manager
PURPOSE:
Does Council support an agreement with Mile High Flood District (MHFD) to design and construct drainage and flood control improvements along Jackass Gulch, from the Highline Canal to Jamison Way?
PRESENTATIONS:
Staff Presenter(s): N/A
Additional Presenter(s): N/A
SUMMARY:
Jackass Gulch has been actively eroding and sending sediment to the South Platte River for many years. Residents along Jamison Way were increasingly concerned as the creek eroded closer to their homes. South Platte Park was concerned about sediment entering the South Platte River where recent river restoration had occurred, because sediment negatively impacts the cobble substrate and fish habitat in the river. These factors led to a 2017-2018 project to stabilize that reach of the gulch behind Jamison Way.
Significant erosion still occurs upstream of the Jamison Way project. There are approximately 20' tall vertical or overhanging channel banks, fallen fence lines, and active erosion. This continues to generate a significant amount of sediment in flowing water. Sediment (of unnatural amounts) is considered a pollutant in stormwater. It can carry naturally occurring phosphorus which has a regulated Total Maximum Daily Load (TMDL) in the South Platte River, has negative impacts on fish habitat, and its deposition downstream reduces channel and flood capacity.
Jackass Gulch has improvements described in a 1990 Master Plan Report by MHFD including stabilization and flood detention in this area. Some of the property is city-owned open space and other portions are in public drainage easement on private property. The City and MHFD are cu...
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