Six genetically and geographically distinct lineages have been identified in Natrix tessellata, and some or all of these may warrant specific recognition following further research (Guiking et al. 2004).

European regional assessment: Least Concern (LC)
EU 27 regional assessment: Least Concern (LC)

This species is widespread in Europe. The species is assessed as Least Concern for both Europe and the EU27 Member States in view of its wide distribution, presumed large population, and because it appears to be stable in much of its range both in Europe and globally.

In Europe this species ranges from southern Switzerland and Germany (where it occurs both as isolated subpopulations considered to be relicts or introduced populations - Speybroeck et al. 2016) eastwards into northern Austria, mainland Italy, Slovenia, the Czech Republic, Slovakia, Hungary, Romania, Bulgaria, Ukraine and southern Russia, and southwards into Croatia (where both historical reports and recent sightings also exist from the offshore islands of Kirk and Cres but "have been debated"- Speybroeck et al. 2016), Bosnia-Herzegovina, Serbia and Montenegro, Macedonia, Albania and Greece (including the islands of Lesbos, Crete, Rhodes, Serifos and Samos, although it is otherwise absent from most Mediterranean islands). In northern Russia and Ukraine, it occurs as isolated relict subpopulations in warmer, hilly areas (Kotenko et al. 2011). Baier et al. (2013) recommend further research to confirm its occurrence on Cyprus, and to clarify whether any subpopulation here is native.

Outside Europe the snake ranges from Türkiye into Syria, Lebanon, Israel, Jordan and northern Egypt (the Nile Delta and lower Nile Valley), and eastwards through the Caucasus (Russia, Georgia, Armenia and Azerbaijan), Iran and Iraq, and Central Asia (Turkmenistan, Kazakhstan, Tajikistan, Uzbekistan, Krgyzstan and Afghanistan) to northwest China and northern Pakistan. It is apparently absent from the Arabian Peninsula, and with no confirmed records from the far north of Saudi Arabia bordering its Jordanian range (Egan 2007, Branch et al. 2008). A record from Yemen, based on a single juvenile specimen, is considered uncertain (Egan 2007), and may represent an erroneous locality (Branch et al. 2008, Merbert 2011). It was until recently known only from a historical report in Pakistan, but has been rediscovered in this country (Masroor and Mebert 2012). Both known Pakistani localities lie within valleys in the western Karakorum range and it has been suggested that the snake may be confined to these refugia, which lie at the southeastern limit of its global range (Mebert et al. 2013). It occurs from sea level up to 2,800 m asl.

This species is common in much of its range. This species has been subject to monitoring at sites in a number of European range states, and while local declines and extinctions have been reported in areas subject to habitat deterioration, including declines within relict subpopulations in Germany and Swizterland (e.g. Mebert et al. 2011, Rote-Liste-Gremium Amphibien und Reptilien 2020) it generally occurs at high densities and most studied subpopulations are stable e.g. Ukraine (Kotenko 2011), Switzerland (Mebert et al. 2011), and Romania (Carlsson et al. 2011). Although most German subpopulations appear to be moderately stable following historical declines, the authors of the national Red List caution that stability cannot be assumed (Rote-Liste-Gremium Amphibien und Reptilien 2020). It appears to be extremely rare on Cyprus, being known from only four specimens collected between the 19^th Century and 2007 (Göçmen and Mebert 2011), where however it may not be native (Baier et al. 2013).

This is a largely aquatic species associated with rivers, coasts, streams, lakes, ponds and the surrounding terrestrial habitat, including those in agricultural and other disturbed areas. It may be the most aquatic snake in Europe, with a preference for larger waterbodies than the related viperine snake (Natrix maura), and records exist of animals foraging along the shoreline at Trieste on the Black Sea coast (Speybroeck et al. 2016). It is active both diurnally and nocturnally, and can be almost fully nocturnal in southern parts of the range during the hottest months (Speybroeck et al. 2016). It occurs in some coastal areas along the Mediterranean, Black and Caspian Seas. It appears emerges from hibernation from the middle of March to the beginning of April through most of its range. The activity period typically lasting from March to October (Speybroeck et al. 2016). The species lays a clutch of between 5 and 37 eggs, with juveniles emerging in August or September (Speybroack et al. 2016).

This species appears not to be globally threatened. It is threatened by loss or modification of wetland habitats in parts of its range, for example through river channelization and lake-shore development. This species is considered to be threatened in a number of western and central European range states. It is often killed by road traffic, particularly in the mating season. As with many snakes this species is generally persecuted by people. Habitat destruction by invasive plant species is a threat in parts of its range, as is pollution.

This species is collected for the international pet trade in Egypt, Syria and Iraq (S. Baa El Din pers. comm.)

This species is listed on Annex II of the Bern Convention and it is protected by national legislation in a number of countries. It also appears on Annex IV of the Habitats Directive. It is presumed to occur in many protected areas throughout its range. Habitat restoration, monitoring and targeted conservation projects for this species are underway in several range states (Mebert 2011 and papers therein). It is listed as threatened in some western parts of its range, including both Germany and Switzerland where it occurs as isolated relict populations. The species has been reintroduced to part of its former range in eastern Germany (although unauthorized introductions in an area north of the Rhineland-Palatinate in 2010-2011 failed to become established - Rote-Liste-Gremium Amphibien und Reptilien 2020). Further research into the taxonomic status of this species is needed, and while it is well-studied new distribution records and rediscoveries have been reported in recent years (Masroor and Mebert 2012, Göçmen and Mebert 2011). Eradication of invasive wetland plant species may be an important future conservation action.