[Edit]Ecology
The Yauza reaches its maximum width of 65 meters three kilometers from its inlet, near the sluices south from the former German Quarter. A barge is filled with rubbish dredged from the river. Inflatable barrier visible on the surface traps the flotsam and directs it to the dredging boat on the left.
Further information: Urban runoff
The industrialization of the Soviet period polluted the Yauza drainage basin to a point where "an oil-soaked tributary of Yauza burst into flame in 1971"; the Yauza itself "was called a river only by force of habit... the biggest gutter for waste in Moscow"[5] and caused a prominent surge in Moskva River pollution below the Yauza inlet.[46] By 2005 this surge disappeared, although pollution levels in the lower Yauza remained 2–3 times higher than in the Moskva just below the Yauza inlet.[47]
Untreated filthy surface runoff was (as of 2008)[9] the main source of pollution; in the 1980s it contributed one to eight times more petrochemical waste than directindustrial waste.[48] As of 2008, nearly 80% of the surface runoff in the Central Administrative District is still flushed into the Moskva and Yauza untreated.[9] Until 2000 the river was used in winter as a dump for snow collected from the streets, adding chlorides, soot, rubbish and more oil into the mix.[49] This practice is now banned; the city now employs a network of snow-melting dumps that feed polluted water into treatment facilities.[49]
Pollution levels gradually decreased in the 1990s and 2000s, as riverside factories were closed and converted (or completely rebuilt) into offices and housing;[6]by 2008, industry contributed less than 10% of the city's waste water.[8] The historical Kristall distillery ( 55°45′25″N 37°40′32″E) in Lefortovo remains the last major industrial pollutant on the Yauza.[50][51]
Ruddy shelducks on the Yauza,Lefortovo District
Between 2001 and 2007 the city drained the lower stretches of the Yauza, swept poisonous sediments off its bottom and plugged hundreds of illegal sewage outlets.[50] The city commissioner's report for 2007 registered a significant decrease in pollution levels between 2006 and 2007 alone (a similar decrease was recorded in 2005[47]), and reclassified Yauza water from "dirty" (pollution index of 4..6) to "polluted" (index just below 4), specifically mentioning high levels of iron and manganese.[6]
In 2008, however, the trend reversed and pollution in the Yauza exceeded its 2006 levels.[7] The petrochemical content in the Yauza was more than three times the national limit (2008: 0.93 mg/l vs. 0.3),[52] suspended particles fivefold (2008: 56 mg/l vs. 10.25).[52] Iron, manganese, formaldehyde, chemical oxygen demand and biochemical oxygen demand (BOD5) also exceeded the maximum allowed limits.[52][53] The Yauza tributaries (except the Ichka River) are still rated as either "dirty" or "very dirty" (pollution index 6..10).[6][52] The city (as of 2008) planned the rehabilitation of the Yauza tributaries Chermyanka and Likhoborka,[51] which was then threatened by shortage of funds in the wake of the 2008 Russian financial crisis.
The upper, cleaner stretch of the Yauza is home to about 20 species of fish, predominantly burbot, perch, crucian carp and gobio,[11] but the lower Yauza also has a population of hardy fish. Perch caught near the Yauza inlet in the 1990s contained over 250 times the maximum allowed amount of petrochemical substances.[54] The abundance of crucian carp became public in April 2008, when an accidental release of hot water from a power plant killed over a hundred fish near the Rostokino Aqueduct.[55]Gobio albipinnatus, a fish that was believed to be extinct in the Moscow Oblast, was rediscovered in the Yauza and the Setun River in 1993.[56]