Greg McKenna is concerned he could lose half his crop if he has to stop irrigating. (CBC)

Some farmers on P.E.I. have been given notice that the province is getting so dry they have to soon stop irrigating their crops.

Rainfall on the Island since May 1 is less than half the average, and July has been especially dry, with rainfall running less than a third of the average.

About 25 farmers have permits to use streams and rivers to irrigate their fields, but the province has warned some of them that the rivers they use are getting too low to sustain irrigation.

"We're trying to protect the environment, and protect the streams," said Sean Ledgerwood, watershed specialist with the Environment Department.

Fish habitats are threatened by lower water levels, says Sean Ledgerwood. (CBC)

"If it gets to that level that it's too low then we just have to say the stream can't sustain this, so you'll have to make your own arrangements."

Ledgerwood said central Queens County is suffering the most, with parts of the Dunk and Bradshaw rivers the lowest.

Farmers in the area say they understand environmental concerns, but they're also worried if they are forced to stop irrigating they'll lose a substantial part of their crop.

Greg McKenna, who grows 200 hectares in the Emerald area, said he could lose half his crop, if he is forced to stop irrigating.

"Right now we know we're going to be lucky if we even break even," said McKenna.

McKenna spent $750,000 on his irrigation system.

"We've got two buyers, Cavendish Farms and McCains, they depend on us to give them a good product. They employ a lot of people, we employ a lot of people, and there's a balancing act involved here I think."

MacKenna's spent $750,000 on irrigation equipment.

"We've invested a lot of money to set up to do this job. When we need the water the most seems to be the point in time where we're going to get cut off," he said.

Fish habitats are in danger if water levels dip down too far, said Ledgerwood. Government is monitoring river levels, and the order to stop irrigation could come at any time.