Marine Lake in Weston has closed temporarily due to concerns about bathing safety.
On Wednesday, a bather became stuck in the mud and had to be rescued by North Somerset Council's seafront rangers.
The hot weather has also led to a deterioration in the water quality at the lake, so the council has taken the decision to close and drain it.
Cllr Mike Solomon, the council’s executive member for neighbourhood and community services, said: “With the current spell of hot weather, we're seeing increased usage of the lake.
"Although we've been able to remove a lot of the built-up silt within the lake during the spring, the majority still needs to be removed when we've got the permission to do so.
"While we'd hoped to be able to re-open the lake for the whole summer, Wednesday's incident and the water quality means that we have to rethink. I'm pleased to hear that the person who became stuck yesterday is okay.
"We need to be confident that this won't happen again. Public safety is paramount.
"The draining of the lake will enable us to do some urgent exploratory work to understand the extent of the issue before refilling and refreshing the water. We're committed to doing this work swiftly to give us the best opportunity of re-opening the lake during the summer."
The council is continuing to work closely with Weston Marine Lake Mudlarks on the future arrangements for the restored lake.
Claire Trevor-Roper, one of the directors of the Mudlarks, said: "It's such a shame that we need to close the lake again right at the start of the school summer holidays, but given the volume of silt that still needs to be removed from the lake we shouldn't be surprised.
"This is a temporary issue and we'll continue our work with the council to ensure that the lake can be restored and enjoyed by many people for years to come.
"While taking a dip or a swim can be a great way to cool off, we all need to take care around the water, understand the hidden dangers that can lie beneath and know what to do if we find ourselves in trouble."
Marine Lake recently reopened for the summer season following the first stage of a £300,000 project to improve the popular community facility.
MORE: Marine Lake opens for summer season.
High tides had been used to naturally ‘flush out’ as much of the lake’s compacted silt as possible with new orange and white buoys installed in the lake to mark changes in water depth due to silt removal.
Work to improve the lake is set to resume in the autumn. An application for a licence to remove around 30,000 tonnes mechanically of remaining accumulated silt has been submitted to the government's Marine Management Organisation with an outcome expected in the next few months.
The council’s investment in Weston’s Marine Lake is part of a £700,000 Great Lakes project which will also involve work to revitalise Clevedon and Portishead's coastal lakes.
Clevedon's Marine Lake is also temporarily closed and drained due to deteriorated water quality, with refill expected on the weekend's high tides.
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