Agenda Date: 07/06/2021
Subject:
Title
Resolution 26-2021: Authorizing an amendment to an intergovernmental agreement (IGA) with Mile High Flood District regarding final design, right-of-way acquisition, and construction of drainage and flood control improvements for Jackass Gulch at High Line Canal
Body
Prepared by: Carolyn R Roan, Water Resource Manager
PURPOSE:
Does Council support amending the agreement with Mile High Flood District (MHFD) to contribute additional funds to the design and construction of drainage and flood control improvements along Jackass Gulch, from the High Line 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. Residents along the gulch are concerned about the loss of private property due to erosion, and safety risks.
Jackass Gulch had improvements described in a 1990 Master Plan Report by MHFD including stabilization...
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