Waltham Forest Council needs to find a wildlife charity to manage Walthamstow Wetlands (WW) to avoid losing an estimated £366,000 a year for the next 20 years.

The site is one of the largest urban wetlands in Europe and, in 2014, the council received a grant and five years of funding from the National Lottery Heritage Fund to open it to the public.

This lottery funding expires in September, after which the council is contractually obliged to maintain the site, with the same level of activity, for the next 20 years.

In total, this means the council estimates it will lose more than £7.3 million by 2040 unless an alternative can be found, which it hopes will reduce the cost to £5.53 million.

Read more: Wetlands visited by more than 700,000 in two years

A report, to be presented to the cabinet on March 19, states: “Associated revenue costs have been reviewed in detail and reduced as much as possible.

“Procuring a delivery partner to take full responsibility for running the WW, conserving the natural landscape and habitats, maximising commercial income and external fundraising will reduce the subsidy provided by the council.

“It will maximise the opportunities for attracting external funding from trusts and foundations, many of which do not fund local authorities directly.”

The council’s current partner is the London Wildlife Trust, who originally intended to provide an endowment fund to create a charitable trust to manage the site, according to the report.

However, this never materialised “due to the financial climate at the time” and the creation of the trust was “put on hold to ensure the most appropriate management arrangements could be agreed”.

Read more: Chingford road one of London's worst for run-off pollution

The report adds: “Public access to open spaces in urban areas, such as the WW, has well documented social benefits, including mental health and other physical benefits.

“Developing a sustainable funding model will ensure that the WW remains open to all, and local residents in particular.

“Volunteering is already an important aspect of the WW operations; this will be boosted within the new contractual arrangement, providing more opportunities for local people, reducing social isolation and improving well-being.”

Alternative solutions, such as setting up a charitable trust now or allowing Thames Water to manage the site, are “deemed to be less favourable than working with a charity with the profile, expertise and track record to make successful applications”.

Read more: Calls for halt to Enfield incinerator amid climate fears

If the council is unable to find a suitable partner by September, it is proposed that the existing contract with the London Wildlife Trust is extended by up to six months until one can be found.

Whoever manages the site, the council will still be ultimately responsible if the lottery and other funders do not get a return on their investment.

The cabinet will vote on the proposed change of management at the meeting on March 19. If agreed, the search for a new partner charity will then begin.

East London and West Essex Guardian Series:

For more breaking news, local headlines and features, ‘like’ our Facebook page.

We also have a Twitter account: @ELondonGuardian

Follow us to keep up-to-date with news in Waltham Forest and Redbridge.