LAHE TAHOE andamp;#8212; It is understandable that those who recall the 1960 Winter Olympics at Squaw Valley would want to have another Olympics in the Tahoe area. The 1960 events catalyzed an unprecedented 20-year spurt of development (more than 70 percent) in the Tahoe Basin even though almost all the events were outside the basin.Proponents of another Winter Olympics (which will have many more events than 1960) suggest that improving the Tahoe access infrastructure and updating aged structures could be done in a manner that would improve the environment using new technology and intelligent planning.This sounds prudent and promising especially for those with vested interests. However, it is impossible to minimize or mitigate the deleterious impact of more people, more buildings (and their infrastructure), more vehicles (particularly buses) and roads, and their consequence of more lake pollution and damage to the fragile Tahoe basin landscape.The past 30 years of fairly steady decline in Lake Tahoe’s clarity (a loss of more than 30 percent) and the lake’s food web changes are directly attributable to the large increase in fine particles (less than 10 microns) and nutrients (nitrogen and phosphates) entering the lake. The particles come from known sources: soil erosion, runoff from roads, parking lots and driveways, vehicle exhaust and air pollutants from as far as the Sacramento Valley or perhaps China.These fine particles become suspended in the upper water column, and disperse the light rays entering the lake causing a loss of clarity. The nitrogen and phosphorus gets washed into the lake from fertilizers, (mainly off lawns and golf courses), animal waste, leaky sewage, and local combustion emissions (smoke). These nutrients cause increased growth of green algae which has expanded 400 percent since the 1960 Olympics, and if its growth is accelerated by another burst of development the lake may become more green than blue.An algae-green or muddy-brown Lake Tahoe is a real possibility that planners must consider if extensive and permanent residential/commercial/transportation construction is in the Winter Olympics’ regional plan. Today’s environmental changes enumerated here are based on well-documented data collected since 1960, not on opinions or impressions.These and other facts are publicly displayed at the Tahoe Environmental Research Center at the Sierra Nevada College in Incline Village. It’s not easy to grasp the true picture because it’s difficult to see the lake becoming less clear and less blue over time unless you actually measure it.Try to think of what Lake Tahoe and its landscape might look like in 2030 as the price to pay for one more Winter Olympics andamp;#8212; bringing an estimated 1 million visitors, many from places historically less concerned about the environment than we citizens of the Tahoe region.The choice to have or not to have the Olympics is not a choice between the environment and the economy; rather it’s a choice between slowing Lake Tahoe’s changing environment or accelerating these unwanted changes so that they soon become visible to everyone on every day. This huge decision should be made by the citizens who care, and it should be unanimous.John H. Eisele Jr., MD, is a Truckee resident.