You are now in California and the U.S. category.

Nervous investors, concerned about their nest eggs, will check the financial markets. Is the New York Stock Exchange up? What direction is the NASDAQ moving?

For people living in the American Southwest, water levels in reservoirs play the same role. And Lake Mead is the blue chip, the biggest, most consequential, most widely watched piece in the game. When water levels are up, spirits are unburdened. People are confident in their place in the desert.

Wedged between Arizona and Utah, less than 20 miles up river from the Grand Canyon, a soaring concrete wall nearly the height of two football fields blocks the flow of the Colorado River. There, at Glen Canyon Dam, the river is turned back on itself, drowning more than 200 miles of plasma-red gorges and replacing the Colorado’s free-spirited rapids with an immense lake of flat, still water called Lake Powell, the nation’s second largest reserve.

If item number one on your summer to-do list is to witness the booming waterfalls of Yosemite National Park, you’re in for a treat. Water levels appear to have rebounded from four years of drought and we’re now in a window of peak waterfall conditions.

United States Geological Survey numbers indicate water under the Pohono Bridge at the west end of the Yosemite Valley has been climbing, and reaching heights not seen since 2012.

I want to be absolutely clear that whatever it takes, we cannot allow the twin tunnels to ever be built. Sized for a capacity of 15,000 cubic feet per second, they are capable of taking all the water that flows down the Sacramento River for half of every year. The tunnels are the ultimate vampire capable of sucking the Delta dry.

We must stop the tunnels, but that is not enough. We must conserve water on farms and in cities. We must replenish our aquifers and build new off-stream reservoirs like Sites north of Sacramento and Los Vaqueros near Brentwood.