Parts of the River Valley lost water Friday and are being asked to conserve or boil their water through the weekend. The area most affected is Interstate 40 and up Highway 59 to Lowe's in Van Buren, but the entire area could be facing shortages.As of Sunday, the city of Van Buren extended its boil order to include Mount Vista and Vista Hills, South of I-40, South to Hynes St, between Fayetteville Rd and N 13th St, South to Northview St, and the Heritage Heights and Park Heights Subdivisions.The city of Cedarville is also under a boil order.Steve Dufresne, Van Buren utilities director, said the water loss is due to the shutdown of the Lee Creek Water Treatment Plant in Fort Smith."The whole region basically gets its water supply from the city of Fort Smith," Dufresne said.Dufresne said he doesn't know how long people will be without water. His team is working on a possible revalving to help solve the problem."The city of Van Buren has adequate storage for normal situations but this has happened in peak usage season so we're asking everyone to reduce their usage," he said.The seven-day forecast for the River Valley has high temperatures at 97 degrees and lows at 76 on Saturday and Sunday.Treatment Plant Shut DownThis news came a day after Fort Smith asked people to conserve water due to a treatment plant shutdown.On Aug. 2, crews reported a mechanical problem at the Lee Creek Water Treatment Plant, according to an email sent from the city. Workers partially shut down the plant and were able to return it to full production.But crews then discovered another maintenance issue and had to shut down the Lee Creek Plant completely to fix it.The city doesn't expect the plant to be back to full production until Aug. 12.