Impact of Water Quality on Aquatic Life in River Ravi, Pakistan

This study assessed the water quality at the outfall of six drains in River Ravi at Lahore, Bridge and Balloki Barrage and B-S Link canal to check suitability of water for propagation of fish and aquatic life. The water quality parameters like pH, EC, DO, COD, BOD, TDS, SO₄ and heavy metals (Fe, Cu, Cr, Ni) were analysed at the outfall of six drains and three other locations on the river in 62 km stretch. The sampling period includes wet and dry weather seasons and canal closure periods. The study reach included the effect of urban and industrial effluents from the six drains and dilution effect of flow augmentation through Q-B Link canal. The results showed that the river water quality was not suitable for aquatic life during dry weather and canal closure period when compared with U.S.EPA standards for fish and aquatic life. The DO, BOD and heavy metals were not within the safe limits. Augmentation of about 600 m³sec^-1 discharge through B-Q Link helps to improve the water quality of the Balloki Barrage pond. However, during canal closure period the situation aggravates as this additional freshwater is not available during December and January. The river water quality at Lahore remained unsafe for aquatic life. The wet weather helps to flush out and slightly improve the water quality during July and August. Nevertheless, the storm water also brings heavy pollutant load from the city to the river. The study concluded that the disposal of untreated drainage effluent to the river remains as a major threat to its water quality and consequently the aquatic life.