DC WASA is asking its customers in a large section of of Northwest D.C. not to use their tap water until further notice due to a temporary spike in chlorine levels.

The boundaries of the affected area are MacArthur Blvd. NW to the west, Western Ave. and Eastern Ave. NW to the north, the Amtrak railroad tracks to the east, Upshur St. NW to the south on the east side of Rock Creek, and Calvert to Observatory Circle to W Street on the west side of Rock Creek. We’ve put together a rough map of the area below — if you’re unsure whether your home or office falls into this area, you can call the DC WASA 24-hour Command Center at (202) 612-3400 to find out. UPDATE: Switched out our hastily drawn map for a better version courtesy the comments.

UPDATE II, 11:34 a.m.: WASA has updated the boundaries of the affected area to a smaller section that includes Rock Creek Parkway to the east, Western Ave. to the west, Military Road to the north, and Porter Street to the south.

UPDATE III, 12:39 p.m.: New boundaries from WASA: Between Connecticut Ave., River Rd., Western Ave., & Nebraska Ave.

We’ll keep you posted as soon as the all-clear is given. WASA spokesperson Alan Heymann tells us the warning will most likely only be in effect for a few hours.

View Chlorine Spike 4/20/10 in a larger map

Officials say the spike happened early this morning while DC WASA’s Fort Reno facility was offline for routine maintenance. Operators at the Bryant Street Pump Station identified a drop in the reservoir at Fort Reno at about 7:30 a.m. this morning, which meant that it was possible a chlorine spike had occurred. WASA staff then confirmed a higher-than-normal chlorine concentration in the water.

This year’s annual switch from chloramine to chlorine was scheduled to last much longer than usual — from Feb. all the way through to May 17 — instead of the usual 30 days or so.

If you live in this area, did you notice an even stronger odor and/or taste to your water this morning? Was it irritating to your skin or eyes?

WASA says it has notified the EPA of the chlorine spike.