Conservation key to summer water supply

One sprinkler system watering can use up to 2,500 gallons of water, she said. Many homeowners, particularly new homeowners, may not be aware of how often or deeply a system is programmed to water.

"This is our last chance to avoid Stage 4," Emadiazar said. "I don't know that everyone understands, even though it's out there. At Stage 4, we are rationed water as a city—that's water for public health, sanitation, quality of life."

In 2012, data from the city of Frisco weather station showed residents could do without watering 31 weeks out of the year, said Public Works Director Gary Hartwell.

"Without knowing it, our residents are actually using rainfall to supplement their irrigation systems," Hartwell said. "It should be the other way around. We should be using our irrigation systems to simply supplement natural rainfall."

Lake levels

Lavon Lake, the district's main water supply, is well below its normal level for two reasons: the drought and a zebra mussel infestation at Lake Texoma, which is 28 percent of the water district's supply.

Limited spring rains failed to fill Lavon Lake, so the district started the summer with a much lower water supply level than previous years, Deputy City Manager Henry Hill said.

The NTMWD, which includes Frisco, on June 1 imposed Stage 3 restrictions for the third time since 2006.

"That's why [the water district] pushed to go to Stage 3 sooner," Hill said. "They don't have that same buffer of volume in the lake they've had historically."

Although July rains were welcome, they were not nearly enough to change the water supply problem through the peak usage months of June-September, city staff said.

"It's important to keep in mind that only the water that falls in Lavon Lake's basin impacts its level," Emadiazar said. "I recall the district indicating it would take an additional 15 inches of rain to regain its normal elevation."

Planning by the district to secure additional water sources is a significant part of the long-term solution, but water conservation on a local level is of the upmost importance to the future water supply, said Denise Hickey with the NTMWD.

Lake Texoma

Several factors combined to put roadblocks in the district's path to restoring the water supply from Lake Texoma.

Zebra mussels, discovered in the lake in 2009, multiply rapidly, cause environmental and economic damage, and can colonize in pipelines and restrict water flow.

The NTMWD has been unable to access the lake's water supply since that time.

The district planned a $300 million pipeline extension project, where the Lake Texoma water supply will be transported by closed pipeline directly to the district's Wylie Water Treatment Plan.

Before construction could begin, however, the water district had to deal with a federal environmental act.

With the Texas/Oklahoma border realignment in 2000, five of the district's six pumps in the Texoma Pump Station were no longer in Texas, Hickey said.

Because the pumps were moved to Oklahoma territory, when zebra mussels were found in the lake, the Lacey Act came into effect. The act is a federal law prohibiting the transportation of waters infested with invasive species across state lines.

The NTMWD received an exception to the Lacey Act in December 2012 and the pipeline project moved forward. It is scheduled for completion sometime in early 2014, Hickey said, which means Lake Texoma water can again be used.

What does the future hold?

The district anticipates it will need a new source of raw water supply equal to the capacity of Lavon Lake every decade for the next 50 years to keep up with demand.

In addition to current and planned water sources, the district plans to fulfil 22 percent of the future water supply through conservation and reuse.

Despite the growth of Frisco and other booming cities in the water district, long-range planning will ensure the water supply is sufficient—provided cities continue to push for conservation, Hill said.

Hartwell said he is often asked why Frisco keeps allowing new housing when water restrictions are in place. His answer echoed Hill's:

"We have plenty of water for our current residents. We have the water for our future residents," Hill said. "The issue is this waste of water through irrigation systems."

Hartwell said Frisco has greatly reduced its water usage in recent years through conservation methods.

The city used about 300 gallons per person per day in the early 2000s and now uses in the low 200s, Hartwell said.

Hickey said with more conservation, fewer new water sources will be needed.

To date, The NTMWD said it has secured additional raw water supplies to support the district population for about seven more years.