Campaigners are fighting plans to build hundreds more homes on green fields.
Developer Martin Grant Homes has submitted outline plans for up to 315 homes at Albany Park, to the south of Church Crookham.
The scheme includes a new medical centre, shop, recreational green space, five sports pitches and a multi-use games area.
But the FACE IT (Fleet and Crookham Environment is Threatened) group warns the scheme will ruin cherished countryside and organised an environmental walk around the threatened area to highlight its concerns.
Max Clark, vice-chairman of FACE IT, said part of the walk was along the River Hart, which runs through the proposed development site and, although flooding has subsided, evidence of the recent rainfall on the river levels was obvious.
“Despite recent dry weather, much of the ground was wet underfoot and its value as a water-meadow in storing water and reducing flooding downstream could be seen,” he added.
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Mr Clark said the walk highlighted the value of the landscape character and biodiversity of the Hart Valley, which follows the course of the River Hart from which the district takes its name.
“Its location to the west of Fleet provides an important north-south corridor for wildlife and a wide diversity of environment with its mosaic of hedgerows, ancient woodland with rare plants, scrub, farmland and floodplain wetlands grazed by cattle, horses and sheep. It is rich in wildlife with important concentrations of rare and declining birds, such as skylark and yellowhammer,” added Mr Clark.
He said the number of homes proposed in the area is of concern, including plans to build 450 homes at Grove Farm, a number of smaller developments and "garden-grabbing" schemes, and the introduction of development at Tudgeys Nursery in Crook-ham Village.
“The Edenbrook development is already breaking into open countryside that was farmland and wetland to the west of Fleet and is set to be extended by another 170 homes,” said Mr Clark.
Martin Grant Homes, which is proposing safety improvements to the A287 junction with Redfields Lane, said its application came after a public consultation in October and November.
Andrew Wilson, director of strategic land for the company, said Martin Grant received more than 65 comments and met more than 150 people at its exhibition at Zebon Copse.
“Where we can, we have listened to and incorporated feedback from the public and comments on the need for new medical facilities, retail and protecting green space have been built into our refined proposals,” he said. “We are confident we have developed a scheme that strikes the right balance between providing high quality homes and protecting and enhancing the local environment.
“We believe the new roundabout upgrade at the A287 Redfields Lane junction will improve travel times and reduce congestion.”
Residents have until April 24 to comment on the application. Hart District Council aims to make a decision on it by May 7.