An extra month's supply might not be a big issue for a single winery, but when the entire industry is grappling with an extra month worth of product, it adds up. Jon Moramarco's calculations put the extra volume at 24 million cases, or 8 percent above average. The last time the industry faced such a glut was the early 2000s, but the industry was also enjoying stronger growth. "We had a marketplace that was growing 3 percent or 4 percent, so that inventory was able to be used up much more quickly," he said. "With a market only growing about 1 percent, it's going to take a while to work through ... "