Work has begun on a new wetland habitat in Cornwall designed to alleviate flooding from the Tamar Estuary.
A 15m (50ft) breach has been made in the banks of the River Tamar to allow water to flow into an area of farmland near Cotehele House in St Dominick.
The National Trust said the intentional flooding of the plain would attract new types of wildlife.
It was hoped areas including Cotehele Quay car park would be protected during high tides and heavy rains, it said.
The trust first announced the plans in April as part of a £250,000 scheme funded by itself and the Environment Agency.
The site would be transformed back into an original flood plain on the River Tamar, the border between much of Cornwall and Devon, offering an "intertidal habitat for wildlife" over the next decade, the trust said.
It was hoped a range of wildlife, including worms and wild birds such as the shelduck, redshank and teal duck, would be attracted to the site, it added.
Property manager Alastair Cameron said: "By creating new wetland habitat similar to that found before the embankment was built, we can make space for nature and water.
"This month, we've made a relatively small breach in the bank and now we'll let nature and the tides take their course.
"It's really exciting to see the water flowing in now with the spring tides."
Rob Price, from the Environment Agency, said those involved were "very much looking forward" to monitoring its benefits.
"This valuable work is an important part of an integrated programme of works to build the Tamar catchment's resilience to a wide range of environmental pressures, including those related to climate change," he said.