As part of the U.S. Geological Survey's National Water Quality Assessment (NAWQA) program nitrate transport in groundwater was modeled in the mid-Snake River region in south-central Idaho to project future concentrations of nitrate. Model simulation results indicated that nitrate concentrations would continue to increase over time, eventually exceeding the U.S. Environmental Protection Agency maximum contaminant level for drinking water of 10 milligrams per liter in some areas. A subregional groundwater model simulated the change of nitrate concentrations in groundwater over time in response to three nitrogen input scenarios: (1) nitrogen input fixed at 2008 levels; (2) nitrogen input increased from 2008 to 2028 using the same rate of increase as the average rate of increase during the previous 10 years (1998 through 2008); after 2028, nitrogen input is fixed at 2028 levels; and (3) nitrogen input related to agriculture completely halted, with only nitrogen input from precipitation remaining. Scenarios 1 and 2 project that nitrate concentrations in groundwater continue to increase from 10 to 50 years beyond the year nitrogen input is fixed, depending on the location in the model area. Projected nitrate concentrations in groundwater increase by as much as 2-4 milligrams per liter in many areas, with nitrate concentrations in some areas reaching 10 milligrams per liter. Scenario 3, although unrealistic, estimates how long (20-50 years) it would take nitrate in groundwater to return to background concentrations-the "flushing time" of the system. The amount of nitrate concentration increase cannot be explained solely by differences in nitrogen input; in fact, some areas with the highest amount of nitrogen input have the lowest increase in nitrate concentration. The geometry of the aquifer and the pattern of regional groundwater flow through the aquifer greatly influence nitrate concentrations. The aquifer thins toward discharge areas along the Snake River which forces upward convergence of good-quality regional groundwater that mixes with the nitrate-laden groundwater in the uppermost parts of the aquifer, which results in lowered nitrate concentrations. A new method of inputting nitrogen to the subregional groundwater model was used that prorates nitrogen input by the probability of detecting nitrate concentrations greater than 2 mg/L. The probability map is based on correlations with physical factors, and prorates an existing nitrogen input dataset providing an estimate of nitrogen flux to the water table that accounts for new factors such as soil properties. The effectiveness of this updated nitrogen input method was evaluated using the software UCODE_2005.

In the last forty years Colombia has descended into a quagmire of chaos and violence unmatched in the history of modern western civilization. Leftist insurgent groups, who seek the violent overthrow of the national government, are opposed; by right-wing paramilitary groups in a bitter civil war that has claimed the lives of hundreds of thousands of people and displaced millions more. The conflict has resulted in a partition of the country in which the national government in Bogota has essentially no control over 40% of its territory. The civil war has been fueled on both sides by billions of dollars of drug profits funneled to the participants each year by shadowy drug cartels that operate illegally in Colombia's vast interior. The violence has spread to the society at large causing widespread crime, corruption, and human rights violations. The situation has become so confusing with the insurgents, paramilitaries, and narcotraffickers so intertwined, that it's nearly impossible to determine who is murdering whom. The chaos not only menaces Colombia, it has regional implications. It has the potential to spillover to Colombia's neighbors threatening several recent positive developments in South America, including democratization, growth of free markets, economic integration, the rule of law, and civil- military relations. Despite the gravity of Colombia's current situation, a cursory review of its history would lead one to wonder how it arrived where it is today. It has been a shining example of participatory constitutional government, maintaining faithful for nearly two hundred years to the formulas implanted in its revolution.