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California and Nevada work together to protect the stunning blue waters of Lake Tahoe, but now Nevada wants out of the partnership, unless it gets some concessions. From Reno Public Radio, Brandon Rittiman reports.
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BRANDON RITTIMAN: Mark Twain wrote that while fishing in Lake Tahoe, he could see the gills on a trout open and close 84 feet down.
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RITTIMAN: For a more scientific measure of clarity, the University of California Davis sends out a research vessel to take readings every 10 days. Biologist Brant Allen explains to passengers why clarity matters.
Mr. BRANT ALLEN (Biologist): Well, you've all - since you've been on the lake, you've all seen how beautifully clear Tahoe is, and that incredible blue color. But the reason we have that is we have this really small watershed compared to the volume of the lake.
RITTIMAN: Tahoe is 22 miles long, 12 miles wide and more than 1,600 feet deep. To measure clarity, scientists clip a small, white disc onto a cable and lower it into the lake until it disappears.
Unidentified Woman: And gone.
Mr. ALLEN: So keep an eye on where you lost it, and I'll bring it back up.
RITTIMAN: When they started keeping track of clarity back in the 1960's, you could see the disc as far down as 102 feet. Now, Allen says, the readings only average about 70 feet.
Mr. ALLEN: On the current path, the lake was just going to continue losing clarity at about 1.2 feet per year.
RITTIMAN: Fortunately, the trend slowed in the last few years. Clarity's not getting better, but not getting worse. Scientists say that's partly because California and Nevada started tackling the problem together.
With an act of Congress, they created the Tahoe Regional Planning Agency, or TRPA. The agency did something drastic. Spokeswoman Julie Regan says it imposed a cap on the amount of ground landowners could cover with buildings.
Ms. JULIE REGAN (Spokeswoman, Tahoe Regional Planning Agency): It's almost like a cap-and-trade system for development. If you wanted to build a hotel or a business, you would have to tear one down somewhere else in order to do that.
RITTIMAN: Fewer buildings mean less erosion. And that means less dirt and nutrients flowing into the lake to make the water murky. Nevada's biggest problem with the TRPA is its voting structure. It takes a supermajority to approve projects. As few as four of the 14 board members can block a development. There's a reason those rules are so strict.
To get a good view of the problem, you can take the Heavenly Ski Resort gondola to an observation deck. Elevation: 9,000 feet.
Ms. ROCHELLE NASON (League to Save Lake Tahoe): You are looking at one of the worst things that ever happened to Lake Tahoe.
RITTIMAN: That's Rochelle Nason, who heads the League to Save Lake Tahoe. She points down to a neighborhood called the Tahoe Keys on the South shore in California.
Before the TRPA existed, developers dug canals so they could build new lakefront property - lots of homes with boat docks. They dug right in the middle of a pristine meadow and marsh, which naturally filtered the main river flowing into Lake Tahoe. Nason points to ribbons of brown water just offshore.
Ms. NASON: You see a plume of sediment.
RITTIMAN: The TRPA put an end to shortsighted projects like the Keys. But Nevada says it's also stalling redevelopment.
Mr. ROGER WITTENBERG (Hotel Owner): We're all together on not wanting to pollute the lake.
RITTIMAN: Roger Wittenberg is building a hotel on the Nevada side.
Mr. WITTENBERG: We're all together on wanting to see the lake improve, actually. The real debates begin when we talk about: How do we go about doing that?
RITTIMAN: Wittenberg wants to do his part by tearing down an old 1940s casino on the North Shore of Tahoe. He'll shrink the casino floor and build a green-certified hotel complex called Boulder Bay. In fact, the new hotel will capture its own runoff water, sending almost none into the lake. To the TRPA board, that makes it an easy sell, right?
Mr. WITTENBERG: It took four years to go through the process.
RITTIMAN: Stories like Wittenberg's led Nevada to demand relaxed voting standards. If California and Congress don't agree to the change by 2017 at the latest, Nevada plans to pull out of the TRPA. That would leave the states to go their separate ways: two sets of rules, which many fear would not protect one giant lake.
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RITTIMAN: For NPR News, I'm Brandon Rittiman.