Rivers, one of the greatest sources of freshwater on the planet may be in peril according to a new study recently published in the journal Nature. The study found, among other things, that rivers worldwide are experiencing similar stresses and are being degraded. Rivers most removed from human populations – in the arctic and the tropics – appear to be in the best state.
The symptoms of this degradation are almost as complex as the causes. Agricultural intensification, industrial development and river habitat modification were noted in the majority of the world’s watersheds. No longer limited to the developed world, the damage appears far-flung and crosses many economic and cultural boundaries. These stresses can reduce or eventually eliminate the flow of the rivers. In the case of agricultural use, this may benefit a few upstream dwellers but may spell disaster for those living downstream. A classic example is the Colorado River in the United States; because of extensive agricultural diversions of water from the river, the Colorado no longer consistently flows into the Gulf of California. In fact, the course of the river below Yuma, Arizona, is often dry.
Another concern is the growing amount of pharmaceutical and chemical discharge that is making it into the rivers of the world. Water treatment systems which are well-suited for removing solid waste and other waste products of humans are increasingly ill-equipped to remove the waste chemicals that have become prevalent in the modern world. Household cleansers, out-of-date medications and even birth control medications are routinely sent down the drain and subsequently discharged into the rivers. In the case of birth control medications, the synthetic hormones are showing up in fish on a routine basis.
Couple those forces with industrial pollution and a toxic stew is brewing in the rivers of the world. Mercury from coal fired power plants is sent into the air and gradually settles back to the earth. When it rains, that mercury is transported directly into rivers and streams. Mercury levels are rising in fish caught in the world’s rivers.
All of this sounds very dire, indeed. In fact the authors of the study, Charles Vorosmarty and Peter McIntyre, found that governments where spending increasing amounts on remediation and cleanup after a watershed has already been compromised. Instead, the authors suggest, strategies such as protecting watersheds can reduce the costs of drinking water treatment, preserve floodplains for flood protection and enhance rural livelihoods. The message seems to be the right one; let’s hope that the right people are listening.