Fireworks at Lake Tahoe on the 4th of July offers one of the most spectacular displays that exists anywhere. The reflective light off the lake adds to the splendor of the show and provides a remarkable visual experience.

But perhaps we should all consider the arguments of the courageous couple who filed a legal action to stop these events and the resulting contamination of the Lake. Their primary argument was that fireworks do not disappear when they explode in the sky. In fact, the fiber-based material mostly falls to the Earth (or the lake) once the explosions are completed. We do not see this no-longer-glowing trash fall to the lake at night because, well, it is night.

In addition to the trash that is scattered far and wide, the propellants that push the fireworks into the sky and the wide variety of chemicals that produce the colors do not disappear entirely. Chief among them is ammonium perchlorate, which is a rocket fuel. Other chemicals include a variety of dyes, some of which are metal based, that provide the spectacular colors that we all find fascinating.

So, another, more ominous view of the fireworks display is that a variety of problematic chemicals are burned in an inefficient manner on a barge in one of our nation's most spectacular lakes. Several years ago, at the request of a resident at Lake Tahoe, we took water samples following the fireworks display. We noted the visual trash that landed on the lake, but also found perchlorate in the water near the display.

Perchlorate is a substance that interferes with thyroid function, and several states, including California and Nevada, have had problems with perchlorate in ground water. California has regulated the substance at 6 parts per billion in drinking water. Perchlorate comes from both human and natural sources, but no matter where it originates, perchlorate does have health effects at low concentrations.

The contractors who conduct the fireworks display do make a major effort to retrieve the exploded trash, and the lake is indeed large, so the perchlorate does get diluted. But we should all take pause and know what we are doing. The lake is a public resource that almost everyone considers a public treasure.

About 15 years ago, a controversy evolved at Lake Tahoe over the use of carbureted two-cycle engines that propelled personal watercraft. Following study by the University of Nevada, Reno, University of California-Davis, the Lahontan Water Quality Control Board and the Tahoe Regional Planning Agency, a decision was made to restrict the type engines that could be used on Lake Tahoe.

The result was a 90 percent reduction in gasoline contamination in the lake through a conversion to a less polluting engine. This win-win situation was a compromise that respected the general belief that large-scale contamination of the lake was not acceptable. Perhaps fireworks displays on the lake are also not acceptable, and some other display should be encouraged, or the current number of fireworks events reduced to the single one that celebrates the nation's birth.

Many years ago, bonfires were started at the top of Yosemite Falls, and when dusk came, the burning logs were sent over the top of the falls and tumbled down in their burning glory to the base of the falls. At some point, over 40 years ago, a decision was made that Yosemite Valley and Yosemite Falls were sufficiently spectacular that additional human effort was not necessary for the public to enjoy the splendor of the park. Maybe Lake Tahoe is the same. Allowing large amounts of burned trash and problematic chemicals to fall into the lake may not be worth the thrill.

Glenn Miller is a member of the faculty of UNR's College of Agriculture, Biotechnology and Natural Resources, and director of the Graduate Program in Environmental Science.