The addition of up to 50,000 dairy cows in Northern Colorado in the next few years will mean more air pollution in the region.

That includes ammonia emissions, which contribute to the build-up of nitrogen in Rocky Mountain National Park, an outdoor icon and key Front Range tourist draw.

The cows' digestives processes also will lead to more methane, a greenhouse gas that the Environmental Protection Agency says traps heat in the atmosphere more effectively than carbon dioxide.

Weld County already boasts a total of 550,000 cattle including 50,000 dairy cows.

Spread throughout the region, the additional cows are expected to produce 4.5 million pounds of milk by the end of next year, said Wade Meek, member services director for Dairy Farmers of America in Colorado.

The farmer-owned cooperative has agreed to supply that milk to the new Leprino cheese plant in Greeley. That level of production will require 30,000 more dairy cows, but the plant someday will have capacity for additional production, which would require 50,000 cows, Meek said.

Now fully operational in its first phase with 100 workers, Leprino is building its plant in three phases, company spokesman Ted Wietecha said. The