Washington Times: With its cable cars and stylish architecture, Expo Zaragoza 2008 is the pride of this northeastern Spanish city, offering a feel-good theme of water and sustainable development until mid- September. Boisterous summertime crowds pack sprawling exhibits showcasing liquid natural treasures, from European rivers and lakes to Middle Eastern oases. Local bands rock late into the night. But there is a sobering message behind Zaragoza’s international fair — growing demand and the …