Tipner Lake forms the north eastern section of Portsmouth Harbour

Portsmouth Harbour

Portsmouth Harbour is a large natural harbour in Hampshire, England. Geographically it is a ria: formerly it was the valley of a stream flowing from Portsdown into the Solent River. The city of Portsmouth lies to the east on Portsea Island, and Gosport to the west on the mainland...

. Although referred to as Tipner Lake, it is not an actual lake

Lake

A lake is a body of relatively still fresh or salt water of considerable size, localized in a basin, that is surrounded by land. Lakes are inland and not part of the ocean and therefore are distinct from lagoons, and are larger and deeper than ponds. Lakes can be contrasted with rivers or streams,...

. However the reclamation of land north of Horsea Island

Horsea Island

Horsea Island was an island located off the northern shore of Portsmouth Harbour; gradually subsumed by reclamation, it is now connected to the mainland...

 and the building of the M275

M275 motorway

The M275 is a long, dual three-lane motorway in the county of Hampshire, southern England. It is the principal route for entering and leaving Portsmouth. It continues as the A3 into Portsmouth, and meets the M27 at its northern terminus...

 motorway in the early 1970s, which passes over a bridge to the west of the lake, can give the impression the body of water is no longer connected to the harbour. The lake is also connected to Portsbridge Creek

Portsbridge Creek

Portsbridge Creek is a tidal waterway that runs between Portsea Island and the mainland from Langstone Harbour to Tipner Lake...

.

Much of the lake is a site of special scientific interest

Site of Special Scientific Interest

A Site of Special Scientific Interest is a conservation designation denoting a protected area in the United Kingdom. SSSIs are the basic building block of site-based nature conservation legislation and most other legal nature/geological conservation designations in Great Britain are based upon...

 as well as being a Ramsar wetland of international importance

Ramsar Convention

The Ramsar Convention is an international treaty for the conservation and sustainable utilization of wetlands, i.e., to stem the progressive encroachment on and loss of wetlands now and in the future, recognizing the fundamental ecological functions of wetlands and their economic, cultural,...

. The site also falls within the Portsmouth Harbour special protection area.

Moves to reclaim the land to provide extra space for the expansion of Portsmouth

Portsmouth

Portsmouth is the second largest city in the ceremonial county of Hampshire on the south coast of England. Portsmouth is notable for being the United Kingdom's only island city; it is located mainly on Portsea Island...

were rejected in the early 1990s on environmental grounds.

The lake is home to the Richard Farrington "Jack Star" sculpture which was installed in late 2000.