Surface Water. COCKREHAM ISLAND BUY-OUT FEASIBILITY STUDY. The Cockreham Island Flood Hazard Reduction Buy-Out Study: Cockreham Island is located between the Towns of Lyman and Hamilton, in Skagit County, Washington, and is adjacent to the Skagit River.
And we certainly see a decrease in NOx without a significant increase in HC or CO. So, in some instances, buying a slightly higher octane fuel can both increase performance and help pass a failed emissions test. Generally, yes, spending money on higher octane than your owner's manual recommends is a waste of money. But sometimes ethanol tilts the scales. Of the 6 vehicles I've owned, 2 benefited from slightly higher octane-the other 4 suffered.
Here in Colorado, gas stations sell regular gasoline which is rated at 85 octane ((M+R)/2). In most of the rest of the US, 87 octane is the lowest grade available. (As noted previously, higher octane fuel can withstand higher compression without detonation.) According to this article from AAA, the stated reason is that most of Colorado is at high elevation, above 5000 feet (about 1500 meters), and the thinner air tends to prevent detonation. Therefore, in theory, one can use the cheaper, lower octane fuel without problems, and save some money.