Energy Resources of Australia Ltd. (ERA) shares fell to the lowest since 2005 after the uranium producer controlled by Rio Tinto Group forecast a first-half loss of as much as A$50 million ($52 million) as rain curbs output.

Energy Resources dropped 11 percent to A$6.88 at the 4:10 p.m. close in Sydney, the lowest settlement since Jan. 10, 2005. The Darwin-based company has slumped 63 percent the past year. The benchmark S&P/ASX 200 Index slipped 0.3 percent.

Processing of ore was suspended in January at the Ranger mine 260 kilometers (162 miles) east of Darwin in the Northern Territory because of heavy rain. Energy Resources extended the halt until July to allow water to drain from storage ponds. Mining operations have “recently ceased” after near-record rainfall and will resume once the water level recedes, the company said yesterday.

“Two consecutive years with substantially lower than planned tonnages and associated revenues, along with one of the heaviest wet seasons on record has had a very significant impact on the business and will continue to do so in the future,” Chief Executive Officer Rob Atkinson said in notes for a speech to the company’s annual general meeting today.

Energy Resources forecast a first half loss of between A$30 million and A$50 million after the market closed yesterday. This compares with profit of A$22.7 million in 2010. The company also estimates output in 2011 at about 2,400 metric tons of uranium oxide, compared with a previous projection of about 3,793 tons.