Hacketts Marsh is closed to the public due to a restrictive covenant order which was inherited with the sale of the property. Access is only available on guided walks or by prior arrangement with site manager. A public footpath runs along the western boundary.
The saltmarsh and meadows are grazed by cattle in summer and autumn on a carefully controlled rotation. A hay crop is occasionally taken from the outer paddocks not the SSSI. Scrub is cut back in the winter along with some pond management. Some willow coppicing, hedge-laying, fencing repairs and other small projects are usually undertaken annually. There is only one other site in Hampshire where there is a natural transition from unimproved pasture to saltmarsh without any artificial delineation or tidal control.
Elsewhere sea walls have been constructed, adjacent areas of grassland improved or the saltmarsh invaded by Common reed through neglect. In addition Hacketts Marsh is extremeley rich in plants which are indicative of a long period of uniterrupted traditional grassland management and saltmarsh species. The site is thus of outstanding conservation value. In 1987 a survey concluded that the site is worthy of SSSI designation on entomological value alone.
The Titchfield Estate map produced in c1610 is the earliest extant document which describes the area around Old Bursledon. The course of the River Hamble appears not dissimilar from today and Hacketts Marsh is shown, whilst land above the reach of tides is pictorially represented as enclosed fields with stylised boundaries. This confirms that the area is ancient countryside i.e. fields woods and roads etc. date predominantly from before A.D. 1700 and are not the result of planned large scale enclosure during the eighteenth and nineteenth centuries.
The Bursledon Tithe Award Map drawn up in 1840 to regulate payment of parish tithes accurately depicts field boundaries and defines land uses. Many boundaries present today are shown but whilst the whole area is now permanent pasture in 1840 many of the fields on higher ground were arable. Hacketts Marsh is listed under the 'Roads, Commons, Waste and mud/sand section of the award.
The drove was thus used by Commoners as a route for livestock down on to the marsh from the road and is undoubtedly an ancient feature. The marsh was not enclosed until 1857 along with other wastelands or Bishops Waltham Manor, though the enclosure award states that no fences were required. Field boundaries remained unaltered barring a few minor deletions when the first edition 6" to the mile Ordnance Survey Map was surveyed in 1866-68.
It was not until the late 19th century when the railway was constructed that a number of boundaries were adjusted to the field pattern of today. It is interesting to the saltmarsh note that the branching, meandering creeks which dissect have remained virtually unchanged since 1868 and as elsewhere around the coast are a relatively permanent feature.
There are a number of hedgerows with mature oaks which are prominent features of the local landscape. The meadows are species-rich and support large hybrid heath spotted orchid populations, meadow thisle, corky fruited water dropwort, devils-bit scabious and sneezewort. The saltmarsh vegetation is dominated by cord grass and saltmarsh grass with sea purslane,glasswort, sea lavender, thrift, sea aster, sea rush and sea club-rush.
The reserve is of particular importance for a wide range of insects (some nationally rare), and forms an important feeding area and high-water roost for waders, (especially lapwing, golden plover, black-tailed godwit, curlew, greenshank and redshank), wildfowl and herons. The site is of high landscape quality.
The 1987 survey showed 44 species that were locally rare; 14 species that were nationally scarce or regionally rare; and 6 that were nationally rare (red data book species). These include two species of soldier flies, and a species of horse fly. The site is also important for waders and wildfowl including migratory species, both as a feeding site and also as a high water roost. The marsh also contains areas of open water for species such as dragonflies which use these areas for breeding and hunting.