For more than half a century, San Diego County has imported water to meet the needs of its population. Our economic vitality and quality of life continue to be dependent on this foundation of imported water. Yet, our heavy reliance on this imported supply has been compromised by a sustained seven-year drought in the Colorado River Basin and an ever-increasing demand on that same water supply from Arizona and Nevada for their growing needs. San Diegoís dependence became even more vulnerable after a recent court ruling to protect a 3-inch fish in the Sacramento Bay Delta. This judicial decision will shut down important pumps in the Delta used to transport water to 20 million Southern California residents. This six-month shutdown has heightened concerns over water supply and, in some cases, prompted undue adversity toward housing and commercial construction.

Clearly, San Diego needs to establish its water independence to protect the future of its nearly 3 million residents. The San Diego County Water Authority has been working toward this goal for years, seeking to diversify our water supply and decrease the percentage of imported water in the region's total supply mix. There is a well-thought-out plan in place. San Diego is not unprepared, despite conflicting media reports.

When it comes to new home and commercial construction and our water supply, San Diego is ill-served by an either-or debate. The facts will support this. A great deal has been accomplished to preserve our water future, including how area builders help to conserve by providing water-smart homes with water-wise products.

The home-building industry has for decades led the effort to increase water conservation in new housing, and new homes today are the most efficient in history. Everything from plumbing systems and fixtures to landscape design has been addressed. Additionally, the home-building industry sponsored and advocates the California Green Builder Program, which requires each new home to save 20,000 gallons of water per year.

Conservation is and will continue to be critical to our future. It deserves everyoneís close attention and commitment as we move forward. Combined with storage and conveyance improvements, conservation helps San Diego accommodate its inevitable growth. In addition to voluntary efforts, existing California law (SB 221 and 610) requires that new communities must have an identified and documented permanent water supply before any construction can begin.

What needs to be understood is that new homes and office buildings arenít the big water consumers. Eighty-five percent of California's water supply is consumed by agriculture. That number jumps to 97 percent in Imperial Valley. But local agriculture businesses clearly understood that if water cuts were needed they would be the first affected. This was part of the deal when they received reduced water rates.

Older, existing urban homes and buildings also consume a bigger source of San Diegoís water supply than new homes. So far this year, only 5,587 new homes were built and sold in the county. Clearly, the water impact of these families in these highly efficient homes is a mere drop in the bucket compared with the 1.13 million existing homes that likely have less efficient water heaters, five-plus gallon toilets and outdated appliances.

Our industry was also actively engaged in the development of a model Water Conservation Landscape Ordinance for the region that saves at least 30 percent more water than existing home landscapes. If residents didnít overwater their landscaping, San Diego would save 8.6 percent of its supply every year. New drought-tolerant landscaping could reduce the regionís water use by almost 13 percent a year.

Even where the majority of new housing is being built helps to save water. The urbanization of San Diego means more townhomes and condos using less water for landscaping, and these residential structures are far more water friendly overall than previous buildings on the same site.

San Diegans should be encouraged by the amount and variety of action occurring in the name of water autonomy. On the civic leadership side of things, the Water Authority has its Urban Water Management Plan in place, the governor and state Legislature are focused on water solutions, and the Coastal Commission recently approved a private-sector solution with the Carlsbad desalination plant. Our industry led the private-sector business community to actively and vocally support the desalination plant. We delivered 455 letters of support to the commission from our workforce. From a supply side, there is the new Olivenhain reservoir and the height increase of the San Vicente Dam reservoir. Those are only part of the $939 million the Water Authority is spending to store up enough water to aid the county if a crisis cuts off its normal supply. San Diego also has the Imperial Irrigation District transfer agreement at work to bring a supplemental supply from the East.

Southern California's water crisis is everyone's problem, and business, government, agriculture and residential customers should work jointly to achieve solutions. The building industry will remain steadfast in its commitment to help San Diego be water independent, while at the same time, providing families with quality places to live and work.

The Building Industry Association of San Diego represents the business and political interests of its 1,400 member companies and their 140,000 employees who earn a living in development and construction. For more information, visit www.biasandiego.org.

Paul Tryon is the chief executive of the Building Industry Association of San Diego County.