The Canal Saint-Martin is 2 m (6.6 ft) deep and 4.5 km (2.8 miles) long, with over 2 km (1.2 miles) underground, and connects the Bassin de la Villette to the Port de l'Arsenal. It was commissioned by Napoleon Bonaparte in 1802, along with the Canal de l'Ourcq and the Canal Saint-Denis, to facilitate navigation and supply Paris with drinking water. During the second half of the 19th century, studies on microbiology (notably by Pasteur) revealed that river water was not fit for drinking, and Haussmann decided to create a drinking water network fed by sources located more than 100 km (62 miles) from Paris. Nowadays the spring water or river water that supplies our taps is purified and made drinkable in treatment plants. Completed in 1825, the Canal Saint Martin requires nine locks to make up for a height difference of 25 m (82 ft) down to the Seine. Commercial traffic has now significantly diminished, giving way to extensive tourist activities, mostly involving passenger boats and private leisure boats. The canal is part of a network of waterways managed by the City of Paris. One of the City's partners, the VNF (Voies Navigables de France - French Navigable Waterways), distributes navigation bulletins (timetables, maintenance work) for all its canals. It manages 6,700 km (4,163 miles) of waterways (operations, development, modernisation) in addition to the 130 km (80 miles) maintained by the City.
The canal is a major route for the flow of wildlife. Part of the ecological corridor, it is a key asset which Paris is striving to strengthen through the Biodiversity Action Plan.
The Saint-Martin, Saint-Denis and Ourcq canals now supply a part of the daily requirement of 200 million litres (53 gallons) of non-potable water needed for street cleaning and the sewer system. They also provide boats with a navigable waterway from one part of the Seine to another, avoiding 12 km (7.5 miles) of loops in the river. In total, these canals form a network of 130 km (80 miles) of waterways, maintained by the City of Paris, with 8 km (4.9 miles) crossing through the capital. They are a major route of circulation for biodiversity, now registered in the Regional Ecological Coherence Scheme. The Seine, the canals and all the artificial wet zones - lakes, ponds, fountains and ornamental ponds - constitute the Parisian blue network, a system conducive to the development of aquatic flora and fauna. This bolstering of biodiversity can only occur by means of a dynamic connection between different locations guaranteed by the Paris Biodiversity Action Plan.
The diagnosis of the Paris area carried out by the City has identified and assessed its ecological quality: - biodiversity reservoirs (large green spaces, parks and cemeteries...) where populations of wild plants and animals can find a permanent home; - linear eco-corridors, green or aquatic routes connecting two reservoirs to each other; a road planted with trees and bushes, sections of the Petite Ceinture railway and the canals of Paris are all routes for animal and plant species, facilitating genetic mixing and therefore the survival of species. By strengthening each component of this ecological network, the corridors and the reservoirs, biodiversity will become connected and develop further. The map resulting from this diagnosis will guide future urban development (eco-district, new gardens, green roads) that will be created and maintained in public and private spaces by residents, gardeners, developers, landscape designers and town planners... A precious tool to reduce breaks in ecological continuity, preserve and strengthen biodiversity in Paris.
A new Biodiversity Plan is in the process of being developed to reinforce nature's place throughout the Parisian territory and reduce the carbon footprint of the city. Following an inventory of the biodiversity in Paris, liaising with its citizens and the committed territorial agents at the beginning of 2016 through local dialoguing workshops and contributions to a collaborative platform will bring forward the main themes which will constitute the City's new stategy for all living things.
Tight-knit colonies of striped beige freshwater mussels (Dreissena polymorpha) cover the walls of the canal. They are a close relative of the sea mussel. These colonisers latch onto bikes, safes, bed frames, motorcycles and random items thrown into the canal, using a tuft of filaments known as byssal threads. These mussels feed on plants and microscopic animals floating in the water which they filter at a rate of several litres per hour. When the water level in the locks drops, they close up, “spitting out” the water. They provide a tasty meal for certain fish in the canal – roach, bream and eel – and for American crayfish. These molluscs were originally from Russia and entered French freshwater at the beginning of the 19th century. Very prolific and invasive, they can sometimes block the water ducts.
Animal species are classified as invasive or as pests by ministerial decrees and grouped as follows: - Invasive species found throughout the metropolitan area: raccoon dogs, raccoons, American minks, river rats, muskrats and Canadian geese. - Species that may be classified as pests by an annual prefectorial decree include wild rabbits, wood pigeons and wild boars. The decision lies with the prefects to “choose the periods and procedures for destruction” from those described in the circular and to “specify the areas affected by such destruction”. - Species classified as pests, fixed for a three year period for each department proposed by the prefect upon consulting a specialist departmental team from the departmental hunting and wildlife commission (CDCFS). These are: weasels, beech martens, martens, polecats, foxes, rooks, carrion crows, magpies, jays and starlings. The classification must be justified by one of the following reasons: public health and safety, protection of flora and fauna, prevention of significant damage to agriculture, forestry and aquaculture, or “other forms of property”. It must also take the local situation into account. The classification of a bird species is only possible in lieu of no other satisfactory solutions: scarecrows, sound scaring, nets, hawking, shooting in open season, etc. The same requirements apply to the classification of martens and polecats.
The millstone parapet at the end of the lower quay is home to spiders and ferns. This siliceous rock is as typical of subterranean Paris as are limestone and gypsum, and was used in Paris, especially in suburban areas for housing construction between 1880 and 1930. Its ?vacuolar? structure contains empty pockets giving it good insulating properties. These millstone houses decorated with ceramics, tiles, brick and wrought iron from the beginning of the Art Nouveau movement are part of the iconic heritage of the Île-de-France region.