Department of Utilities
Reference: Approve Brighton Ditch Company Agreement
To: Mayor Gregory Mills and Members of City Council
Through: Jane Bais DiSessa, City Manager
Prepared By: Austin Creswell, Water Resources Engineer
Through: Brett Sherman, Director of Utilities
Brad Dallam, Assistant Director of Utilities
Date Prepared: May 6, 2021
PURPOSE
To consider the approval of an agreement between the City of Brighton and the Brighton Ditch. The agreement is entitled Agreement for Applications for Grant, Design, and Construction Involving the Ken Mitchell Cell 1 Diversion Structure.
BACKGROUND
The City of Brighton operates a diversion structure on the South Platte River that serves as an inlet and outlet for water moving into and out of the Ken Mitchell Cell 1 storage reservoir. In the same vicinity but on the opposite (West) river bank, the Brighton Ditch operates a diversion structure that moves water from the river into the Brighton Ditch. The Brighton Ditch also owns a diversion dam at the same site that spans the river. This diversion dam creates a higher water level on the upstream side, which provides more water to the ditch. These structures are shown on Figure 1.
In 2015 a flood damaged both of these diversion structures and created a washed out area on the East end of the diversion dam on the City’s side of the river. This washed out area allowed the river to freely run around the East end of the diversion dam. Repairs were made after the flood, which included a temporary berm built across the washed out area.
The City has been in discussions with the Brighton Ditch about making more permanent improvements to better stabilize the river bank in the area of the temporary berm. Improvements would include river bank armoring and a high-flow flood channel that would allow floods to safely pass through the area without damaging the structures.
One problem with having a diversion dam in the area is that it causes sediment to accumulate. Brighton has had to deal with an ongoing problem of sediment buildup in and around the City’s diversion structure. As part of this project, Brighton is seeking designs for structures that would improve water flow and decrease sediment buildup at the City’s diversion structure.
The Brighton Ditch and the City have independently worked with consulting engineers to come up with preliminary design concepts that both entities believe will accomplish these goals.
The Colorado Water Conservation Board (CWCB) offers grants for these types of improvements. It is the intention of City staff and the Brighton Ditch to work together to pursue getting these improvements funded through a CWCB grant. CWCB grants require 50% match from the recipients. As partners, the Brighton Ditch and the City would each pay half of the match, or 25% of the project costs if the grant gets approved. If the grant is not approved, the Brighton Ditch and the City will work together to explore other options.
FINANCIAL IMPACT
Costs for the proposed future work are not currently known. This resolution is only to enter into the Agreement with the Brighton Ditch to work together towards a solution, which includes grant funding. As project costs become known, staff will return to Council as needed for approval of funding.
STAFF RECOMMENDATION
Staff believes the described work is necessary to protect existing infrastructure from future floods and to make it more functional. Rather than take on this work individually as a City, a partnership would improve the chances of a grant approval, and provide financial benefits as well as a better working relationship between the City and the Brighton Ditch. Staff recommends approval of the resolution to enter into the Agreement with the Brighton Ditch.
OPTIONS FOR COUNCIL CONSIDERATION
• Approve the attached Resolution as presented
• Deny the attached Resolution as presented
• Postpone consideration of the Resolution with suggested changes
ATTACHMENTS
• Resolution
• Agreement between the City of Brighton and the Brighton Ditch
Figure 1 - Map of Structures