Chatfield Construction Activities Update Part 1
Chatfield Reservoir Mitigation Company
From an email newsletter sent by the Chatfield Reservoir Mitigation Company Team April 2, 2020:
We have officially made it to spring 2020 – the goal set by the Chatfield Storage Reallocation Project years ago to complete the recreational and environmental construction and receive authorization to begin storing water!
As of April 1, 2020, CRMC is thrilled to inform you that all recreational modifications and environmental mitigation work have been completed. We can’t wait for you to visit the new Marina floating building, explore areas of the Park that you may not have visited since construction started over two years ago, and even discover new areas of the Park not previously accessible.
While we find ourselves in unprecedented times with the COVID-19 pandemic, CRMC remains optimistic that we will receive authorization from the U.S. Army Corps of Engineers to allow for water storage in the new reallocation pool later this month.
As we have received several inquiries regarding the status of the project and when the water level will start rising at Chatfield Reservoir, we have prepared answers to some frequently asked questions below.
For information on restrictions and closures at Chatfield State Park due to the COVID-19 pandemic, please visit Chatfield State Park’s website at:
What is the Chatfield Storage Reallocation Project?
The Chatfield Storage Reallocation Project (CSRP or Project) is a partnership between federal and state entities and water providers in the Denver Metro area and northeast Colorado. The U.S. Army Corps of Engineers (Corps) built Chatfield Reservoir in 1975 to control flooding near the confluence of the South Platte River and Plum Creek. Beginning in the 1980s, the Corps and the Project’s stakeholders studied the water supply benefits of “reallocating” a portion of Chatfield Reservoir’s flood storage for multi-purpose water storage.
In response to the increasing demand for water due to the rapid population growth in Colorado, the Corps determined that Chatfield Reservoir could accommodate an additional 20,600 acre-feet of water storage, or about a 12-foot vertical change from the existing operational pool of 5,432’ to 5,444’, for multi-use water storage without compromising its flood-control function.
On May 29, 2014, the Corps signed the Record of Decision for the final Feasibility Report / Environmental Impact Statement (FR/EIS). The FR/EIS outlined the recreational modifications and environmental mitigation required by the CSRP to complete in order for the Project Participants to be authorized to store water in the new reallocation pool.
The Project Participants formed the Chatfield Reservoir Mitigation Company (CRMC) to oversee the design and implementation of the recreational modifications and environmental mitigation.
When will water be stored in the reallocation pool?
The CSRP is currently on schedule to receive all necessary approvals and authorizations from the U.S. Army Corps of Engineers by May 1, 2020. Based upon average snowfall totals and the capacity levels of the reservoir systems along the South Platte River Basin, the Project Participants are hoping for a mid- to late-May timeframe to begin storing water.
How fast will Chatfield Reservoir be filled to the new 5,444’ elevation?
There are several factors involved in how fast and how much the reservoir will fill each year, including weather and flood conditions, the rate of flows from Plum Creek and South Platte River, the calls being made from non-CSRP water rights holders, and the priority status of the Project Participants’ water rights.
If the Project is able to store up to the new 5,444’ elevation, it could take several weeks for that elevation to be reached.
Who will oversee the operations of the reallocated pool?
An Operational Advisory Committee (OAC) was formed in 2018 to oversee the first storage of water as well as the overall operations of the reallocation pool moving forward. The OAC is comprised of the Project Participants, Denver Water, Colorado Parks and Wildlife, Colorado Water Conservation Board, Colorado Division of Water Resources, and the U.S. Army Corps of Engineers. In the event of flood conditions, the Corps will take over control of the operations and determine how much water is stored and released.
What is the Environmental Pool, and will it increase the amount of water released from Chatfield Reservoir?
The Environmental Pool was created as part of the Fish, Wildlife, and Recreation Mitigation Plan (commonly referred to as the 122.2 Plan) between the Project Participants and Colorado Parks and Wildlife. The 122.2 Plan called for the creation of an environmental storage space to provide timed releases to alleviate low-flow conditions downstream of Chatfield Reservoir. The Environmental Pool will comprise up to 2,100 acre-feet of the reallocated storage space and has many benefits including: increasing the flow of the South Platte River during low-flow times, enhancing the river’s health and water quality, increasing recreational activities, and supporting agricultural operations downstream. The Environmental Pool will be managed by Colorado Parks and Wildlife in accordance with the terms of the 122.2 Plan.
What is left to do on the Project?
While all the recreational modifications and environmental mitigation have been implemented, you may see us out at the Park from time to time. A large focus early this spring and summer will be to finish the revegetation efforts, including the replacement planting of trees, reseeding of certain areas, and weed management. We encourage all visitors to please be mindful of these revegetation activities to ensure reestablishment of native grass and shrubs occurs. Throughout 2020, watering will continue along the South Platte River corridor where environmental mitigation occurred, including the planting of nearly 35,000 native trees and shrubs.
Will there be any further activity in the area once the Project is completed?
If any maintenance or repair work is needed that would impact an area built or modified as part of the reallocation project, we will be sure to keep you informed on our website at: https://chatfieldreallocation.org/construction/. Monitoring activities will be on-going, especially in the environmental mitigation areas, for at least the next five years.
What will happen to the trees surrounding the reservoir?
Existing trees within the fluctuation zone (between elevations of 5,432’ and 5,444’) of Chatfield Reservoir are expected to be impacted as the result of recreation modification construction activities and the increase in water elevation resulting in inundation changes under the reallocation. Dead or unhealthy trees in the fluctuation zone are a potential hazard to boaters, other park visitors, and dam operations.
The FR/EIS originally proposed that all trees below an elevation 5,439’ would be cleared, but CRMC, in coordination with local experts, CPW, and the Corps, determined this would be too destructive to the environment. Therefore, a new approach deemed the “Adaptive Tree Management Plan” was implemented to manage the trees.
Beginning in October 2016, CRMC contracted with Colorado State Forest Service (CSFS) to inventory and determine the likelihood of survival with inundation and water storage for all trees within the fluctuation zone. Following CSFS’s inventory, Markit! Forestry was contracted in late 2018 to perform vegetation removal and thinning of 286 acres within the fluctuation zone. These efforts included removing dead and dying cottonwood and willow trees, as well as the removal of non-native species.