MOSES LAKE - Grant County is the third largest dairy county in the state, according to a recent Washington State University study.

The county had 24,500 dairy cows in 2011, or about 9 percent of the state's total.

Yakima County had 93,000 cows, 36 percent of the state's total, and Whatcom county had 51,000 cows, 20 percent of the state's total.

Yakima, Grant and Franklin counties were the only counties in the state that showed a growth in cow numbers from previous years, according to the study.

Between 2006 and 2011, the number of milk cows in Grant County increased by about 48 percent. The county had 16,000 cows in 2006.

The number of cows in Yakima County increased by about 32 percent and the number of cows in Franklin County increased by about 88 percent, according to the study.

Franklin County is the state's fifth largest dairy county based on 2011 data.

The figures come from the 2011 Economic Contribution Analysis of Washington Dairy Farms and Dairy Processing study conducted by WSU Extension's School of Economic Sciences.

It was funded by the Washington Dairy Products Commission, according to a recent news release from the group.

Shannon Neibergs, WSU Extension Economic Specialist, said a similar study was done in 2006. The 2011 study showed there has been significant growth in economic contribution at the dairy farm level since the first study, he said.

In 2011, the state's dairy sectors had an economic contribution of about $5.2 billion, said Neibergs. About $2.3 billion came from dairy farms and $2.5 billion came from dairy processing.

The rest came from the cull cow industry, which is when cows are pulled from the milking herd and sold for meat or other products, he said.

Neibergs said the economic contribution increased by about $893 million from 2006, when the industry delivered a $1.5 billion economic benefit to the state.

That represents a growth of about 61 percent, he said.

"That growth increase is the result of an increase in herd size and an increase in the price of milk," he said.

Washington's herd size has grown by 23,000 head between 2006 and 2011, according to the study.

Neibergs said the 2011 study also showed a shift from the West side of the state to the East side of the state in terms of dairy herd size.

According to the study, about 55 percent of the state's dairy herd is east of the Cascades while 45 percent is west of the Cascades. In 2006, the proportions were the same, however 55 percent was in the West while 45 percent was in the East.

Neibergs said the cost of feed and land is a little cheaper in the East than in the West. In addition, it's easier for operations to expand on the east side of the state, he said.

"Operations on the east side are more likely to have additional acres they could expand on," said Neibergs. "On the west side, with the urban influence and the subdivision of land, it's hard to expand on their home site."

He said operations on the west side of the state might have to expand on non-adjacent land, which is isn't as efficient as managing one site.

Dan Wood, government relations director for the state's Dairy Federation, said it was impressive the industry has more than a $5 billion impact on Washington's economy.

According to the WDPC, the industry's economic benefit to the state is realized in jobs, farm equipment purchases, land leases and acquisitions, feed and seed purchases and taxes.

"The study was undertaken because we need to know the economic impact of dairy," he said, in the WDPC press release.

"Policy decisions are being made at the state and local levels and public officials need to know the value of dairy and the jobs created."