Permanent repair and restoration work on the damaged dam in Whaley Bridge will cost up to £16 million and take two years.
The Canal and River Trust said it planned to begin the work at the end of 2021, subject to planning permission, which would involve installing a new side channel weir, spillway channel and stilling basin on the northern side of dam.
More than 1,500 people were evacuated from the Derbyshire town in August 2019 due to fears the dam wall at Toddbrook Reservoir would collapse after heavy rain.
A permanent repair plan, released by the trust on Tuesday, said the proposed work would cost an estimated £12-£16 million.
The plan also said the auxiliary spillway, damaged in summer 2019, will be decommissioned and the dam slope grassed.
The trust said it hoped the area would be reopened to the public in early 2024 and said high volume pumps will remain in the reservoir to manage water levels until the end of the restoration project.
Before the plans were finalised, a design team considered 13 potential proposals and said their final plan was informed by feedback from local people.
The trust previously said it was “happy” with how the dam was originally built – describing the incident in August 2019 as an “anomaly”.
Speaking after the release of the permanent repair plan, Canal and River Trust north west director Daniel Greenhalgh said: “Repairing the reservoir is a huge engineering challenge and public safety is our top priority.
“The permanent repair design has been shaped by local feedback and guided by modern engineering best practice.
“During the construction phase, part of the park will unfortunately have to be closed, but we hope to be able to move some of the play equipment to an alternative location so it can continue to be available.
“These changes are necessary to construct the new side channel weir, ‘tumble bay’, spillway channel and stilling basin in an optimum alignment, both within the landscape and for reservoir safety.”
Mr Greenhalgh continued: “The stilling basin will then connect with the River Goyt, at the existing location, via a channel through the park.
“The use of a side channel weir allows us to connect the existing reservoir bywash into the top of the tumble bay, which will mean water flows down the spillway at all times.
“We were guided in this design modification by public feedback indicating that a continuous flow of water down the spillway was preferable to having a predominantly dry channel.”