River Tamar
The Tamar is a river in south west England that forms most of the border between Devon and Cornwall. A large part of the valley of the Tamar is protected as the Tamar Valley National Landscape, and some is included in the Cornwall and West Devon Mining Landscape due to its historic mining activities.
The Tamar's source is less than from the north Cornish coast, but it flows southward across the peninsula to the south coast. The total length of the river is. At its mouth, the Tamar flows into the Hamoaze before entering Plymouth Sound, a bay in the English Channel. Tributaries of the river include the rivers Inny, Ottery, Kensey and Lynher on the Cornish side and the Deer and Tavy on the Devon side.
The name Tamar was mentioned by Ptolemy in the 2nd century AD in his Geography. The name is said to mean "great water". The Tamar is one of several British rivers whose ancient name is assumed by some to be derived from a prehistoric river word apparently meaning "dark flowing" and which it shares with the River Thames.
The seventh-century Ravenna Cosmography mentions a Roman settlement named Tamaris, but it is unclear to which of those towns along the Tamar this refers. Plymouth, Launceston and the Roman fort at Calstock have been variously suggested.
Environment
The river is designated as a Site of Special Scientific Interest, a European Special Area of Conservation, and an Area of Outstanding Natural Beauty. A part of it is also designated as a UNESCO World Heritage Site as part of the Cornwall and West Devon Mining Landscape.In November 2013, South West Water was fined £50,000 after it admitted permitting the discharge of sewage from its Camels Head treatment plant into a tributary of the River Tamar for eight years.
Tamar Valley National Landscape
Together, the Tamar, Tavy and Lynher form the Tamar Valley National Landscape, a designated Area of Outstanding Natural Beauty. The Tamar Valley Area of Outstanding Natural Beauty covers around around the lower Tamar and its tributaries the Tavy and the Lynher. It was first proposed in 1963, but was not designated until 1995. The highest point in the AONB is Kit Hill, 334 metres above sea level. The Tamar Discovery Trail is a 35-mile hiking route following the course of the Tamar through the valley.Special Area of Conservation
The Plymouth Sound and Estuaries are a Special Area of Conservation. Rocky reefs in low salinity estuarine conditions far inland on the Tamar are very unusual and support species such as the hydroid Cordylophora caspia. The Tamar is one of a few estuaries where zonation of rocky habitats can be observed along an estuarine gradient.Site of Special Scientific Interest
The Tamar–Tavy Estuary is a Site of Special Scientific Interest covering the tidal estuaries of the River Tamar and the River Tavy. Part of the Tamar estuary also forms the Tamar Estuary Nature Reserve, owned by the Cornwall Wildlife Trust. The site was designated in 1991 for its biodiversity and varying habitats that support a large number of wader and wildfowl species, as well as the special interest of its marine biology. The site supports a nationally important wintering population of avocet and supports species such as black-tailed godwit, Eurasian whimbrel, greenshank, spotted redshank, green sandpiper and golden plover.UNESCO World Heritage Site
Throughout human history the valley has been almost continuously exploited for its rich mineral and metal deposits including silver, tin, lead and arsenic leaving a unique archaeological landscape which forms a significant part of the Cornwall and West Devon Mining Landscape. Remains include wheal or engine houses, deep and open cast mines dating from the Bronze Age through to the medieval and modern era, the export docks at Morwellham Quay were once an international centre of trade in copper, lead and arsenic. The valley, with the stannary town of Tavistock was added to the World Heritage List during the 30th Session of the UNESCO World Heritage Committee in Vilnius, July 2006.Water quality
The Environment Agency measures the water quality of the river systems in England. Each is given an overall ecological status, which may be one of five levels: high, good, moderate, poor and bad. There are several components that are used to determine this, including biological status, which looks at the quantity and varieties of invertebrates, angiosperms and fish. Chemical status, which compares the concentrations of various chemicals against known safe concentrations, is rated good or fail.| Section | Ecological Status | Chemical Status | Overall Status | Length | Catchment Area | Channel |
| Heavily modified |
Geography
Reservoirs
The Upper Tamar Lake and Lower Tamar Lake are two small reservoirs on the Tamar's upper course. The Lower Lake was constructed in the 1820s to feed the Bude Canal; it is now a nature reserve. The Upper Lake was constructed in the 1970s and supplies fresh water to the Bude area, as well as having some recreational use.Border
The east bank of the Tamar was fixed as the border of Cornwall by King Athelstan in the year 936. Several villages north of Launceston, to the west of the Tamar, were transferred to Devon at some point in the eleventh century when the border was changed to follow the River Ottery westward, rather than the Tamar. The county boundary was restored to the Tamar in 1966, when the civil parishes of North Petherwin and Werrington were transferred from Devon to Cornwall. The Counties Act 1844 ensured parishes were entirely within one county. It transferred a part of the Rame Peninsula from Devon to Cornwall. The Act also transferred part of the parish of Bridgerule to Devon and part of the parish of North Tamerton to Cornwall — these latter transfers created two of the present-day 'exceptions' to the river boundary.The modern administrative border between Devon and Cornwall more closely follows the Tamar and Hamoaze than the 'historic' county border. Only three 'exceptions' to the rule that the border follows the river currently exist, all of which are upstream of the confluence of the River Deer, in the upper course of the Tamar. Part of the Cornish civil parish of North Tamerton extends east across the river, whilst parts of the Devon civil parishes of Bridgerule and Pancrasweek extend west across the Tamar. Where the border does follow the Tamar, it is defined as being along a line running at the centre of the river — where the river is tidal, it is the centre of the low water channel. This "centre of river" arrangement ends just upstream of the Tamar Bridge at Saltash, downstream of which the counties officially extend only to their respective bank's low water mark. The river is dammed at two points of its upper course, forming two reservoirs in place of the natural river: at Upper Tamar Lake the border follows the line of the river as it was prior to the construction of the reservoir, whilst at the older Lower Tamar Lake the border was re-aligned along a re-routing of the river to the reservoir's west side, placing the lake in Devon.
Crossings
The river has 22 road crossings, including some medieval stone bridges. The oldest bridge still extant is at Horsebridge, and the next oldest is Greystone Bridge near Lawhitton — this arched stone bridge was built in 1439. Gunnislake New Bridge was built in 1520 by Sir Piers Edgcumbe, the owner of Cotehele and Mount Edgcumbe. The Gunnislake bridge was a main route into south east Cornwall and the lowest bridge over the Tamar until the Tamar Bridge at Saltash was opened in 1962.The lower Tamar is spanned also by the Royal Albert Bridge, a rail bridge now adjacent to the newer Tamar Bridge. Both of these bridges are between Saltash and Plymouth. Further downstream, crossing the Hamoaze, is the Torpoint Ferry — a chain ferry connecting Torpoint to Devonport — and at the most downstream part of the Hamoaze there is also the Cremyll Ferry.
The Calstock Viaduct is another notable structure on the Tamar, being 120 feet high with twelve 60-foot wide arches, of which three of the piers stand in the river, and was built between 1904 and 1907.
Navigation
The total length of the tidal river is. The normal tidal limit is a weir just downstream of the village of Gunnislake. Waterborne traffic through the Hamoaze is controlled by the Queen's Harbour Master for Plymouth, who is responsible for managing navigation along the entire tidal Tamar. The Royal Navy has one of its three main naval bases at Devonport, situated on the Hamoaze, upstream of which the river is now used largely by recreational craft. Excursions operate on the river between Plymouth and Calstock; excursions used to operate as far as Morwellham Quay, but were suspended indefinitely in 2016. A passenger ferry also operates April to October between Cotehele Quay and Calstock.A typical Tamar vessel was a sailing barge, built on the open river bank, of up to 60 tons, with a peaked, gaff-rigged mainsail and a fore staysail. The Tamar was navigable by seagoing ships of up to 400 register tons as far inland as Weir Quay, near Bere Alston, where the estuary narrows into the tidal river, some upstream from Plymouth Sound. Vessels of 300 tons sailed as far inland as Morwellham, along the river from the sea. A further stretch of upstream to Weir Head, near Gunnislake, is accessible to smaller boats. Weir Head is just downstream of the weir at Gunnislake and is the final place to turn boats; it was from here that smaller craft could begin their journey on the Tamar Manure Canal.