Well, two entries in the same day. Hm. Ah, well.

The essay presented here is a conservationalism essay concerning the issue of dams and their impact on nature (or something of the sort).

Out of the blue, a dozen or so salmon emerge out of the salty sea. The species is not important; for this happens to all salmon. The migration of the salmon sends them from the sea back to the rivers where they were born. But this trip is not like other salmon had taken in the past. This time there is an obstacle, a 150 foot high block of concrete, steel, and man-made wonder.

Easy enough for us to say "it's only a dam", but what about the poor salmon? To them the dam is more than an obstacle. It can be an insurmountable challenge to all who attempt to pass it. Others have died trying to get through it, and these might not be any more fortunate.

People have different views of what is important when it comes to a dam. A free-flowing river provides a thriving fishing industry and plenty of opportunities for recreation, but building a dam also provides short-term jobs and energy.

Those fish at the foot of the dam may find the fish ladders and get to the top and their spawning ground, but their children (called smelts) will suffer an 80% decline going to the ocean. Why? Because of the dam's huge turbines (fans) causing pressure change in the water as they churn the water. The pressure is so great that the little fish are literally crushed. Their swimming bladders explode–killing them instantly. Even worse, half of the fish never come back to produce the next generation. This is not enough to support the fish population.

Enough of that. Not all dams are bad. Some nations need dams for a major boost to their economy. But some people say nature should come first. The best example of this is in Bolivia.

The proposed Bala Dam would make a reservoir (an artificial lake made by a dam) that would flood a thousand square miles of rain forest located in a national park. The dam is not located in the national park, called Madidi, but the lake would be. It should also be mentioned that Madidi claims five different ecosystems (a certain habitat for wildlife). Among them are the Andes, Pampas, and rainforest. It is home to a thousand indigenous species. The park provides money to the villages in the business of tourism. Although there is a good chance that the government will approve it, conservationists are leading the charge against it with some success. They plan to get all the villages into tourism, then altogether oppose the dam with all the inhabitants of the areas that would be affected by the lake and challenge the politicians and engineers that are backing the plan.

But what does a dam do besides kill fish and make energy? Guess. Take for example the Bonneville Dam on the Columbia River - our guinea pig for now. Not only does it: 1) Create electricity, but also; 2) Lifts the water in enclosed areas (called locks) to allow large boats and barges into the water reservoir behind it. This aids shipping upstream. 3) It helps control floods and; 4) Makes irrigation possible. Nevertheless, we must not be too dependant upon our own inventions. Anything we make can be built in a decade - destroyed in a instant. It can be the same story for a dam. All it takes is a tiny crack and the sheer force of the water pushing on the dam can destroy it. And then it is lights out to 20,000 people. Maybe more...

Dams can take a variety of forms to perform different tasks and fit in different environments. A dyke like those in the Netherlands and those around New Orleans is in fact a form of a dam called an earth dam. A rock dam is a very strong dam that looks like a speed bump but is only used as a barrier to keep small amounts of water at bay. The great Hoover Dam is an arched dam; these are usually used strictly for hydroelectricity (electricity made by the dams), not for irrigation. A solid gravity dam is similar to the arched dam in design, but is not curved. Both can support great amounts of water. The hollow gravity dams can be either in the form of a multiple arch or flat slab dams. They both look like an arched wall of columns on the downstream side.

The multiple arch types are wavy whereas a flat slab is... well, flat. But at one time these majestic masterpieces were meant for very different tasks. A humble example is the water wheel and grinding mill. The earliest dam that is still in existence is on the Segura River in Spain. Built in the twelfth century, it is believed that it was meant to be an irrigation dam. Relatively small, compare these structures to the mighty dams that we build now. The Grand Coulee Dam in Washington state, for example is 550 feet high - twice the height of Niagara Falls and is 4,173 feet long. It has enough concrete to make a sidewalk that circles the earth at the equator twice, and the water that it holds is enough for everybody on the earth to have 900 gallons.

Dams can produce a feeling of awe as well as shame. Sure, it is an impressive structure with a very impressive capacity in every aspect, but unfortunately it can also be an instrument of death. For fish, recreation and enjoyment of the thrill of splashing beneath a waterfall; which, you can't get in a lake the size of Rhode Island. The fishing industry is a source of 500 million dollars a year for the Columbia River basin alone. On the other hand, the Aswan Dam in Egypt

converted hundreds of miles of desert into wetlands, aiding agriculture.

Dams, like the water they harness; are great allies, but if used improperly, are fearsome foes. Beautiful, yet ugly, dams are what control the future of the life both above and below the rivers they control. Just like the offspring of that school of salmon at the foot of the concrete mountain.