AGRICULTURAL pollutants pose a major threat to the surface water, farms and the health of the people living in Sindh.
Almost all surface water bodies in Sindh — the Phuleli Canal, Kalri Baghar Feeder, Pinyari Canal, Nara Canal, Rohri Canal, Rice Canal, Ghotki Feeder, Dadu Canal and Pat Feeder — get contaminated by these pollutants.
The Phuleli Canal and Kalri-Baghar Feeder are further affected by the discharge of industrial and municipal wastewater. The canal network system in Sindh is surrounded by land used for agriculture. The discharge or overflow from these lands flows directly into surface water bodies.
This has worsened the water crisis by leading to deterioration in water quality, thus reducing the volume of water that can be used. Agricultural pollutants typically comprise sediments, nutrients, pesticides, nitrates, phosphorus and heavy metals.
Heavy metals such as cadmium, cobalt, copper, nickel, lead, zinc, iron and manganese are found in a number of commercial mineral fertilisers, industrial sludge, animal feed additives, and in some pesticides, herbicides and fungicides.
Pollutants contain dangerous heavy metals such as cadmium, copper, nickel, lead, zinc, and iron, which require costly advanced water treatment systems not available in Sindh
The problem with heavy metals is that they require costly advanced water treatment systems (ultrafiltration, precipitation, biological oxidation, activated carbon, ozonation and ion exchange), which are not available in the water treatment plants in Sindh.
As a result, these pollutants are able to pass through the water treatment systems, ending up in household water storage systems. Drinking water contaminated by heavy metals leads to serious health problems. In infants it can cause methaemoglobinaemia, or blue-baby syndrome, which can be fatal.
In Pakistan, agriculture-related regulations do mention include agricultural pollutants. The Sindh Environmental Quality Standards of the Sindh Environmental Protection Agency (EPA) mention a pesticides standard of 0.15 milligrams per litre (mg/L) for discharge in inland waters. The Sindh EPA has the power to enforce the pesticides standard, but is not doing so.
While the Sindh EPA is responsible for the discharge of agricultural effluent into the surface water, the surface water bodies are the responsibility of the Sindh irrigation department. While agriculture practices are the responsibility of the Sindh agriculture department.
The three institutions need to work together to control the agricultural pollutants, and to achieve the Sustainable Development Goal Target 6.3, which states: “By 2030, improve water quality by reducing pollution, eliminating dumping and minimising release of hazardous chemicals and materials, halving the proportion of untreated wastewater”.
The three institutions can use their respective regulations to control the pollutants. For example, in British Columbia, the westernmost province of Canada, the Health Act and Sanitary Regulations are applied to farm waste on matters of nuisance, conditions affecting human health, and stream pollution.
Another act, the Municipal Act, gives municipal councils certain powers to pass bylaws regarding nuisance conditions, locations of livestock operations, and property line setback distances for buildings. The Water Act aims to stop dumping of waste into streams.
The Federal Fisheries Act has broad powers to prosecute persons whose work results in harmful alteration or destruction of fish habitat. The Pesticide Control Act Regulations exempt farm operators from certification, licensing and permit requirements when operating on their privately owned or leased land, and when using common agricultural pesticides.
The Sindh agricultural department’s extension wing can implement simple measures in coordination with agriculturists to control the flow of agricultural pollutants into the surface waters.
Some of these measures include: establishing stream bank buffer strips, preventing livestock from going into streams by placing fences around streams and constructing facilities to store manure. Furthermore, they can introduce waste minimisation practices to prevent pollution at the source, train field staff and conduct public awareness programmes for agriculturists.
Soil erosion can be curtailed by adopting minimum tillage operations, covering light-textured cultivated soils to prevent flow of sediment into streams, and setting up wetland treatment systems if run-offs are extensive. If field drains are constructed they can help pollutants bypass streams and collect in evaporative ponds.
F.H. Mughal has a master’s in environmental engineering from the Asian Institute of Technology, Bangkok