- What happens here at Lake Mead matters.

Seven Western states, alongwith 29 tribes in Mexico,

depend on the waterthat flows through here.

- The Southwest one of themost heavily populated areas

in the whole United States.

So we are concerned.

- [Heather] 40 million peoplerely on this giant reservoir,

which today is only at one third capacity.

An infamous bathtub ring tells the story.

Lake water last coveredthe whitish minerals

on the rock in the late 1990s.

- This is really new territory,

given that all of LasVegas and many other cities

in the Southwest have reallygrown during that time.

So this is, this is serious.

- To get a better idea,

take a look at the waterlevel in these pictures

at the Hoover Dam from 20 years ago

and compare them to today.

Those who use the lake forboating and other recreation

are well-aware of the shrinking shoreline.

You can see the effects of the drought

here at the Lake Mead recreation area.

They've had to build new rampsjust to get people and boats

into the shallow lake.

- It's scary to think about, you know,

what happens if it drops more.

- When I normally launch myjet ski off Boulder Beach,

and there's probably abouta good 12 to 20 feet of mud

that you can't actuallydrive in, you will get stuck.

- [Heather] The falling levelsand shrinking water supply

didn't happen over night.

It's the result of 20plus years of more heat,

less rain and less runoff.

- Well, we think about droughts now

is it's really a balancebetween that supply,

that lack of rainfall andthe atmospheric thirst.

How dry is that atmosphere?

How much water is that atmospherepulling out of the ground?

- [Heather] On one side,scientists believe the west

has moved beyond temporarydrought towards aridification,

a permanent phase of moredryness and less water.

Either way, western states like Nevada,

are preparing for unwelcome intervention

when the federal governmentdeclares a historic shortage

and water supply is reduced.

- You're looking at about9 billion gallons of water

less that will be availablefor our community.

- [Heather] Southern Nevadagets 90% of its water

from the reservoir.

Thanks to aggressive conservation however,

the water authority here isn't panicking.

The effort dates back to 2002,

when the west drought began in earnest.

- We had pivot very, very quickly

and reduce our water use almost overnight.

- [Heather] What that looks like,

financial incentives forhomeowners to remove grass

and replace it with dripirrigated rock scapes.

Also, limited wateringschedules for these yards,

complete with water police.

They patrol for homes with leaksor not following the rules.

- If they don't take corrective action,

they could end up with a water waste fine

- [Heather] Even more importantis what southern Nevada does

with indoor water.

Get this, it recyclesand reuses 100% of it.

- We could turn on everyfaucet and every shower

in every hotel room on the Las Vegas strip

and it wouldn't increase theamount of water we deplete

from the Colorado river becauseall of that indoor water use

gets reclaimed treated tonear drinking water standards

and returned back to Lake Mead.

- [Heather] Last year, thisconservation allowed the region

to use just 83 billion gallons of water,

far less than its 98billion gallon allotment.

That also means enough marginto absorb the expected cuts.

The work has caught theattention of neighboring states.

The region is partnering withsouthern California right now

to repurpose its treated wastewater,

which up to now has beendischarged into the Pacific Ocean.

Believe it or not LasVegas was founded in part

because of its water supply,

a bubbling spring that helpedstart the city in 1905.

Today it's got a 50 year water plan,

although they're stillconcerned for the future.

Just how much water will theregion have going forward

and how will it accommodatea booming population?

It's why southern Nevada is joining

with other Western statesto ask for up to a billion

in federal dollars to helpbetter understand the drought

and manage the precious supply of water

in some of the country's driest states.

Reporting in southern Nevada,Heather Sells CBN news.