What is killing our rivers?


February 21, 2008 at 15:07 PST
Our nation's rivers have come a long way since the headline grabbing Cuyahoga River fire decades ago, but they are still threatened by multiple forms of less visible pollution. Did you know that at the mouth of most large rivers in the US there is an area called a "dead zone", where human activities have created conditions unfit for all higher forms of aquatic life? Or that the Colorado River, famous for carving the Grand Canyon, is so abused by humans that only a trickle of it occasionally reaches the ocean and that trickle is so polluted that the water would be better classified as toxic waste? Or how about the fact that many of the species of fish that used to inhabit our nation's rivers are now dying out or already extinct? Want to know what is killing our nation's rivers? Read on.

Long before the Cuyahoga River fire sparked dramatic change in the way we view our rivers, other incidents focused public attention on the poor state of some of the world's rivers.  In the 1850's the River Thames became so full of sewage that the House of Common shut it down after being overpowered by the stench.  They soon passed laws regarding the handling of sewage and treatment of drinking water.  Before this incident, sewage was just dumped in the river.  Besides the odor issue, this presented a health problem as well, since people got their drinking water from the river and wells connected to the river.  As a result, water borne illnesses were very common in London before the introduction of sewer systems.  A hundred years later, the Thames faced another set of problems.  Due to high nutrient loads and dumping of other industrial pollutants, large sections of the river were declared biologically dead and were completely devoid of fish.  Spurred to action after being told their river was “dead”, London and other communities along the river have since cleaned up their act and they now claim that the Thames is the cleanest river running through a major city.  

Sadly, these “historical” problems are still widespread throughout the world.  Many 3rd world countries lack sanitation infrastructure and clean drinking water.  Even in the US, as I've touched on in other articles, it is common for raw sewage to enter our creeks, rivers, and oceans untreated.  Dead rivers and dead zones at the mouths of rivers are still widespread phenomena.  Caused primarily by the overuse of fertilizer and lack of treatment of agricultural runoff, these dead zones take quite a toll on coastal fisheries and cost the fishing industry billions every year.  Simple solutions to this problem include using only as much fertilizer as is needed, leaving vegetated and forested buffers around the edges of fields and streams, and planting less fertilizer intensive crops.  Excess nutrients can also be removed in treatment wetlands designed to capture runoff before it enters local streams.

Another threat our rivers face is sedimentation.  When lots of soil enters a stream or river it can clog gaps in gravel or rocks along the bottom of the channel.  These gaps provide habitat for macro-invertebrates that form a crucial part of the food chain.  Fish often lay their eggs in these gaps to keep them safe from predators and from washing away.  Sediment enters our streams through a variety of sources including stream bank erosion, agricultural runoff, land clearing, and poorly controlled construction sites.

While there is often an overabundance of sediment and silt in our smaller streams, there is a lack of sediment reaching some of our nation's most important wetlands.  The rapid disappearance of our Gulf Coast wetlands has received some coverage recently given the ability of coastal wetlands to decrease flooding inland during hurricanes.  One of the reasons these wetlands have been disappearing is that sediment from the Mississippi River, traditionally deposited in and around these wetlands, is no longer reaching them.  This might sound strange given that I just said our actions have lead to larger amounts of sediment entering our creeks and rivers.  So where does all the sediment go?  For starters, a lot of it gets caught behind the numerous dams we've built along our larger rivers.  These dams aid in navigation, help control flooding, and create new recreational opportunities, but by essentially creating a long chain of lakes and drastically slowing water velocity they also trap a large fraction of the sediment that would otherwise be carried downstream to the river's mouth.  

In the case of the Mississippi River, the sediment that does reach the Gulf of Mexico is washed out past the wetlands and deposited farther out to sea.  A major cause of this problem is the numerous man-made channels dredged through the wetlands by oil companies and the Corps of Engineers.  Instead of trickling through shallow, wide, flat wetlands, the river with all its sediment flows through these channels and out to sea.  

The sediment issue becomes even more complicated by the fact that though sediment is needed in some coastal areas, its increased deposition in others has threatened whale-feeding grounds (an issue I learned about in a quarterlife thread).  The problem here is similar to that of the small streams discussed earlier.  Many small life forms make their homes in the silt and mud at the bottom of the sea and estuaries.  If sediment is deposited too rapidly in these areas, these critters that are an important food source for larger animals, can be smothered.  

While water pollution problems have grown less visible (rivers don't catch on fire or turn bright orange all that often these days), they are still widespread and threaten our health and the health of our planet.  Our country has confronted and solved many of the large water quality problems it faced in the past.  Let us hope it continues to do so with these current problems.

Want to know what you can do to help?  Ask me in the discussion thread!


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What is killing our rivers?

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March 01, 2008 - 8:13 AM PST
thealbanyriver on
Dams are one of the biggest problems this planet has ever faced. First, they are killing our rivers and oceans and second are the cover ups by big business and the media. There are over 50,000 large dams and 800,000 hydro eclectic dams and literally millions of dams of all shapes and sizes dotting the faces of this globe. Almost every dead zone is at the mouth of rivers that have been dammed. They have altered the rotation of this planet, change the tides, affected the magnetic field, fishing industries have collapse all over the world because of dams, deltas are vanishing at an alarming rate and this is only a fraction of what damage dams are doing. To many times I have been ridiculed for my belief in dams and the damage they are doing to this planet, why; because if the mainstream media doesn’t say it, it can’t be so. As if the mainstream media tells us the truth. The media is owned and controlled by big business and what big business wants to know is what the media reports. The sooner we turn the TV off and research for our selves the sooner this planet will be a better place to live.
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