[Updated 4:15 a.m. Friday] Isaac, now a tropical depression is working its way up the Mississippi River Valley, bringing heavy rain and the threat of flash floods to the area. A tornado watch remains in effect for much of Mississippi. Parts of Arkansas and Mississippi are under flash flood watches and warnings, according to the National Weather Service.
[Updated 10:35 p.m. ET] And finally ...
[Updated 10:21 p.m. ET] The folks who catch the shrimp we enjoy on our tables are a tough lot, a breed apart. Not a few of them rode out Isaac on their boats.
[Updated 10:09 p.m. ET] Electric utility Entergy says it will bring its Waterford 3 nuclear plant back online over the coming days. The plant, 25 miles from New Orleans, was shut down Tuesday as a precaution as Tropical Storm Isaac approached. About 41 percent of all homes in Entergy's Louisiana service area were without power as of late afternoon.
[Update 10:01 p.m. ET] Louis Armstrong New Orleans International Airport received its first post-Isaac incoming flight this evening, from Aspen, Colorado, Mayor Mitch Landrieu's office says.
[Updated 9:54 p.m. ET] The Salvation Army says it has provided more than 8,000 meals, 7,000 drinks, 6,000 snacks, and emotional and spiritual care to nearly 600 individuals along the Gulf Coast during the storm period.
[Updated 9:44 p.m. ET] New Orleans Saints quarterback Drew Brees tweeted a message of support for the folks back home while the Saints prepared for a preseason game against the Tennessee Titans in Nashville:
[Updated 8:39 p.m.] Storm surge and high winds pushed several pleasure boats out of Mississippi's Pass Christian Harbor, leaving vessels high and dry on streets and in parking lots, CNN affiliate WLOX reports.
"I'd say in one word, it's a mess," Pass Christian Mayor Chipper McDermott told WLOX. "We had 215 boats in the harbor, and all but six or seven got out. As you can see, three are in the road, and that is a big problem."
Boat owners were under orders to remove their vessels from the harbor before the storm struck. McDermott wants to have a word with those who didn't.
"I'm personally taking it upon myself to talk with these boat owners," he said. "I'm personally doing it."
[Updated 8:21 p.m. ET] CNN iReporter Gerard Braud submitted a video report from from the floodwater underneath his elevated house in Mandeville, Louisiana. His generator and lawn mower washed away, he says, and his tool shed moved from one side of his yard to the other.
[Updated 8:08 p.m. ET] A tornado that dropped down from an Isaac feeder band destroyed a home in Pascagoula, Mississippi, Thursday morning, CNN affiliate WLOX reports. The home's elderly residents were not injured, the station said.
"I was actually coming out the side door of my house to get the truck and head to work and this tornado that caused all this damage came through," neighbor Billy Perkins told WLOX. Â "You could see it coming right across these rooftops behind me, through the tops of these trees and hit down on the next house over and just literally exploded the roof off the house."
[Updated 7:43 p.m. ET] With the downgrading of Isaac to a tropical depression, the National Hurricane Center has stopped issuing updates on the storm. All coastal watches and warnings have been discontinued. The storm's sustained winds have dropped to 35 mph, but the system has picked up speed, now moving north-northwest at 12 mph.
[Updated 7:24 p.m. ET] The city of Little Rock, Arkansas, is making sandbags available to residents as Isaac's rains approach, CNN affiliate KARK reports. The city sits next to the large and meandering Arkansas River. Firefighters are handing out sandbags in the city of Conway; those bags are being filled by prison inmates, CNN affiliate KLRT reports.
[Updated 7:03 p.m. ET] Water rescues continue in low-lying areas inundated by storm surge and heavy rain.
[Updated 6:50 p.m. ET] According to the mayor's office, New Orleans' Causeway and Twinspans bridges are open, but several roads and bridges remain closed: I-10 at LaPlace; U.S. 90 around Rigoletes; I-55 by Ponchatoula; and the U.S. 11 Bridge.
[Updated 5:12 p.m. ET] Strong winds and storm surge from Hurricane Isaac's landfall forced the Mississippi River to flow backward for nearly 24 hours on Tuesday, the U.S. Geological Survey said Thursday.
The USGS stream gage at Belle Chasse, Louisiana, showed the Mississippi flowing upstream at 182,000 cubic feet per second, surging to 10 feet above its previous height. Average flow for the Mississippi River at Belle Chase is about 125,000 cfs, toward the Gulf of Mexico, the USGS said.
"Although it doesn't happen often, hurricanes can cause coastal rivers to reverse flow," a release from the agency said. "Between the extremely strong winds and the massive waves of water pushed by those winds, rivers at regular or low flow are forced backwards until either the normal river flow or the elevation of the land stop the inflow."
Storm surge from Isaac has been observed as far north as Baton Rouge, USGS said.
"This reversal of flow of the mighty Mississippi is but one measure of the extreme force of Isaac," said USGS Director Marcia McNutt. "While such events are ephemeral, they are yet another reminder of why we need to respect hurricane warnings."
[Updated 5:03 p.m. ET] About 13,000 customers have lost power in Arkansas as Tropical Depression Isaac approaches the state, CNN affiliate KARK reports.
[Updated 4:45 p.m. ET] Red diesel fuel that washed ashore Thursday morning in Biloxi, Mississippi, came from the fuel tank of a generator at Keesler Air Force Base, CNN affiliate WLOX reported.
Officials said the diesel leaked into storm water, then drained into the Back Bay.
"Once we came out here and actually smelled the diesel fuel and confirmed it, we started immediate recovery teams," Col. Mark Vivians with Keesler Air Force Base told WLOX. "We actually have a contractor coming online to do full recovery of this area and actually capture the diesel fuel and remediate it."
[Updated 4:38 p.m. ET] Isaac is no longer a tropical storm and has weakened to a tropical depression, the National Hurricane Center says.
[Updated 4:31 p.m. ET] Utility company Entergy says on Twitter it has 1,100 people working 16-hour shifts to restore power in the storm-affected region.
[Updated 4:23 p.m. ET] Emergency responders are assessing the dam at Lake Tangipahoa at Percy Quin State Park in Pike County, Mississippi. Heavy rains from Hurricane Isaac damaged the structure, but it has not been breached, Gov. Phil Bryant's office said.
"Heavy equipment and pumps from across the state have been dispatched to initiate a controlled water release from Percy Quin State Park to the Tangipahoa River to relieve dam pressure, which should not significantly increase water levels down stream," the governor's office said.
Mississippi residents south of the dam have been encouraged to evacuate the area until the dam has been secured.
Louisiana Gov. Bobby Jindal confirmed his counterpart's statement: "As we're speaking the folks in Mississippi areÂ in theÂ process of intentionally breaching the dam over in Mississippi," Jindal said at a news conference. "The intent is to allow 8 feet of waterÂ to come out and then reinforce the structural integrity of the dam. If this is successful, based on modeling, ... that wouldÂ not have significant effect on water levels down here."
The water is being released into a heavily wooded area, Jindal said.
[Update 4:08 p.m. ET] There will be no curfew in New Orleans Thursday night, the mayor's office said. The airport is still closed until power can be restored. Streetcars are not running, but many bus routes are operational. Weather permitting, normal garbage collections should resume Friday.
[Update 4:01 p.m. ET] [tweet https://twitter.com/GOHSEP/status/241258426775252993%5D
[Update 3:47 p.m. ET] "It doesn't take but a little breach (in a dam) to make a big problem for all of us," Tangipahoa Parish, Louisiana, President Gordon Burgess said at a press conference. "That water will move south quick."
Burgess, Gov. Bobby Jindal and other officials urged residents within a half-mile of the Tangipahoa River to evacuate the area immediately as a dam was in danger of failing, releasing a flood of water.
[Updated 3:27 p.m. ET] All roads and bridges within the New Orleans levee system are open, with some isolated lane closures, Mike Stack of Louisiana's Department of Transportation and Development says. Ferry service remains suspended.
[Updated 3:19 p.m. ET] Country singer Reba McEntire is raising awareness about relief for Isaac victims:
[Updatee 2:57 p.m. ET] Victims of the flooding in Braithwaite, Louisiana, talk to CNN affiliate WWL about their harrowing escapes.
[Updated 2:50 p.m. EY] Louisiana Gov. Bobby Jindal has just called for the immediate evacuation of the town of Kentwood, CNN affiliate WWL is reporting.
[Updated 2:43 p.m. ET] More than 915,000 customers in Arkansas, Alabama, Louisiana and Mississippi have no power, utility companies tell CNN.
[Updated 2:40 p.m. ET] Forecasters predict that the weakening Isaac will be a tropical depression by this evening. Torrential rains continues to drench the Gulf Coast.
[Updated 2:36 p.m. ET] Officials are pumping water over the dam near Lake Tangipahoa and digging a hole into it - an intentional breach - to relieve pressure on the structure, the Mississippi Emergency Management Agency says.
The agency doesn't expect a catastrophic event, said MEMA spokesman Greg Flynn.
The state has "a good number of prisoners there ready to begin sandbagging if it comes to it," Flynn said.
[Updated 2:18 p.m. ET] We have a couple of nice offerings from Anderson Cooper and Soledad O'Brien. One is a report on how the destruction caused by Isaac in Plaquemines Parish was far greater than that wrought by Katrina. Also, Cooper and O'Brien chat with members of the self-styled "Cajun Navy," private citizens who used their own boats to perform rescues after Isaac struck.
[Updated 2:02 p.m. ET] Let's stop for a cuteness break. If you were following the live blog yesterday, you may have seen an iReport about an 8-year-old leaving a set of instructions for her stuffed animals while she, her brother and mother evacuated ahead of Isaac.
Well, iReport has caught up with Ashley Taylor, who says the media is making a big deal over nothing. She just wanted to make sure her furry friends were safe while she was gone, she said.
From her Gammy and Pawpaw's house in Mobile, Alabama, she told iReport the rules "just came to me." Asked why she forbade the stuffed animals from throwing soirees in Rule No. 4, she replied, "Because theyâ€™ll mess up my room and then my mom will get mad at me."
She added that she is a little embarrassed by all the attention.
[Updated 1:53 p.m. ET] The bridge that connects Dauphin Island to the Alabama mainland has been washed out by water and debris, and it may be Friday before officials can start clearing the causeway, CNN affiliate WPMI reports.
On Wednesday, a boater had to be rescued from his sail boat because of the nasty conditions on the water. The abandoned ship still had its sails raised, and it floated down toward the Dauphin Island Bridge, where it hit a power line that pumps electricity to the islandâ€™s 1,200 residents.
The residents are still without power, WPMI reports.
[Updated 1:38 p.m. ET] In other levee news, Plaquemines Parish President said earlier today that officials planned to breach a levee on the east bank there to relive pressure after Isaac brought massive flooding to the area.
Gov. Bobby Jindal just said during a Baton Rouge, Louisiana, news conference: "We are proceeding with plans to purposely breach that levee today between 2 and 3 p.m. The idea is to allow that water to flow out of that area. Now that the winds have shifted they're planning on having pumps on site to help de-water that area as well."
[Updated 1:31 p.m. ET] Gov. Bobby Jindal says Mississippi officials plan to intentionally breach the dam near Lake Tangipahoa to prevent if from breaking.
The river stood at more than 17 feet this morning, more than 2 feet above flood stage, according to the National Weather Service, which predicted the river could reach 19.5 feet by tomorrow.
Near Kentwood, Louisiana, in the evacuation zone, the river could reach 17 feet, which is 4 feet above flood stage. Officials say an intentional breach would send water into a forested area rather than Louisiana towns, Jindal said.
[Updated 1:19 p.m. ET] We're focusing pretty heavily on the situation along the Tangipahoa River right now, but remember we have a state-by-state breakdown of situations unfolding in Louisiana, Florida, Mississippi and Alabama.
[Updated 1:13 p.m. ET] The Terrebone General Medical Center in Houma, Louisiana, is short on Type O blood, according to CNN affiliate WWL. All types of blood donations are welcome at the hospital's Blood Donor Center, but the need for Type O is most critical. If you're in the area and able to give blood, please callÂ (985) 873-4025 or (985) 873-4029 to set up an appointment.
[Updated 1:09 p.m. ET] The Tangipahoa Parish government has issued a statement on its website saying the dam is damaged but not broken. It says there are shelters at Hammond West Side Elementary Montessori School, Hammond Junior High Magnet School, Natalbany Elementary School, Nesom Middle School, Amite High School and Kentwood High Magnet School.
Gov. Bobby Jindal will hold a news conference at the parish's Council chambers at 2 p.m. CT, the statement says.
An emergency alert beneath the statement calls the dam's failure "imminent."
[Updated 1:03 p.m. ET] While there have been operations all over the southeastern portion of Louisiana â€“ including the overnight evacuation of about 150 people in Plaquemines Parish â€“ rescue efforts homed in on St. John the Baptist Parish last night, said Louisiana National Guard Lt. Col. Mike Kazmierzak.
High-water vehicles, local police and troops evacuated more than 3,000 people, and those efforts are still ongoing, he said. They are heading to shelters throughout the state.
â€śTheyâ€™re getting out of harmâ€™s way,â€ť he said.
[Updated 12:54 p.m. ET] In July, the Enterprise-Journal in McComb, Mississippi, reported that Percy Quin State Park officials planned to work on the dam some time after this coming Monday.
The plan called for Lake Tangipahoa to be drained 6 to 10 feet so the dam and spillway valve could be "reworked," the paper reported, citing park manager Will Busby. The project was slated to take all winter.
[Updated 12:46 p.m. ET] The Louisiana Emergency Management Agency says that if the dam fails, water levels along the Tangipahoa River near Kentwood could quickly reach 17 feet.
[Updated 12:39 p.m. ET] Looks like the confusion is cleared up. The Mississippi Emergency Operations Center says the dam near the 700-acre Lake Tangipahoa has been damaged by heavy rains, but water has not breached the dam.
You can read a PDF of the center's statement here.
Gov. Bobby Jindal says the evacuation order pertains to people within a mile of the Tangipahoa River and is urging everyone in the area to heed the warning.
[Updated 12:10 p.m. ET] Pike County Civil Defense's latest Facebook update says: "Flood warning for the Tangipahoa River at Osyka. The dam at Lake Tangipahoa, better known as Percy Quin State Park, has been damaged by the torrential rains from Hurricane Isaac, but is intact, and is not leaking. We are monitoring it. All residents below the dam that live along the Tangipahoa River are being notified of the damage."
[Updated 12:07 p.m. ET] As of about 20 minutes ago, a National Guard helicopter was maintaining position over the dam to monitor its integrity, The Times-Picayune reports. As of 11:45 a.m., it was still holding, the New Orleans paper reported.
[Updated 12:03 p.m. ET] The National Weather Service is reporting that the dam is "expected" to fail.
[Updated 12:01 p.m. ET] OK, so a small conflict in reports from officials near the Tangipahoa River.
Despite early reports of an apparent levee failure near Lake Tangipahoa, which is close to the Mississippi-Louisiana state line, Mayor Whitney Rawlings of McComb, Mississippi, says Pike County Civil Defense informed him that "the dam is holding, but they are concerned it may fail," WWL reports on air.
He further said it's a coin toss whether it will fail, but, "This might go. People need to be moving now."
Bear with us as we work out the discrepancy in the reports and work to determine whether the dam has failed or is expected to fail.
[Updated 11:55 a.m. ET] Amite, Louisiana, Police Chief Jerry Trabona tells CNN affiliate WWL on air that officers are going door-to-door to residenc s along the Tangipahoa River after a mandatory evacuation was ordered following an apparent levee failure.
[Updated 11:53 a.m. ET] In New Orleans' Central City neighborhood, police arrested six people Wednesday for allegedly looting in the wake of Hurricane Isaac, the Uptown Messenger reports. Police thanked residents in the area for their vigilance in reporting crimes as they were in progress.
[Updated 11:47 a.m. ET] Tangipahoa Parish President Gordon Burgess says Louisiana Gov. Bobby Jindal is sending buses to assist with evacuation efforts after an apparent levee failure near Lake Tangipahoa, CNN affiliate WWL reports.
Asked where the evacuees would be transported, Burgess told WWL,Â â€śWe donâ€™t know yet. I just got to get them out away from the river.â€ť
Burgess says residents - between 50,000 and 60,000 of them - have a little less than an hour to clear out. The evacuation order is aimed at residents along the Tangipahoa River, from Kentwood to Robert, Louisiana.
[Updated 11:37 a.m. ET] Rafael Delgadillo of Braithwaite, Louisiana, says his family is fine after a dramatic rescue that he caught on camera as they escaped their attic. He and his family decided not to heed mandatory evacuation orders because the area where he lives didn't see flooding during Hurricane Katrina seven years ago, Delgadillo said.
[Updated 11:26 a.m. ET] Officials are calling for a mandatory evacuation of at least 50,000 people along the Tangipahoa River - from Kentwood, Louisiana, to Robert, Louisiana - after a levee apparently failed near Lake Tangipahoa, according to CNN affiliate WWL.
As of 10:25 a.m. CT, residents have about an hour and 15 minutes before the water reaches Kentwood, Tangipahoa Parish President Gordon Burgess says.
[Updated 11:17 p.m. ET] Ridgeland, Mississippi, residents got a bit of a scare when tornado sirens went off several times Thursday morning during Isaac's wind gusts and rain, CNN affiliate WAPT in Jackson reports.
For those on the Gulf Coast who've been taking a beating from Isaac, there shouldn't be any reason for concern. Kirk is not predicted to go into the Gulf. A National Hurricane Center map forecasts the hurricane being about halfway between Canada and Europe by Monday morning.
[Updated 10:54 a.m. ET] Please remember that if you're in any of the affected areas and have stories, photos or videos you'd like to share, you can do so at iReport.com's open story. Much thanks!
[Updated 10:51 a.m. ET] Isaac has had a "major impact" on Mississippi, Gov. Phil Bryant said, explaining that emergency crews performed 70 rescues along the state's Gulf Coast overnight.
"This is a man-made beach," he said in Gulfport. "Most of that sand is gone. Thousands of homes have been damaged; people have been out of their homes and will be."
[Updated 10:47 a.m. ET] The National Weather Service reminds residents in Isaac's path that even though Isaac is no longer a hurricane, the tropical storm still poses life-threatening hazards in the form of storm surge, inland flooding and tornadoes.
[Updated 10:45 a.m. ET] Isaac is weakening over central Louisiana, but it's still producing heavy rain, severe weather and high water levels on the northern Gulf Coast, according to the National Hurricane Center's 11 a.m ET advisory.
Presently, the storm is about 50 miles south of Monroe, Louisiana, (and about 165 miles northwest of New Orleans) and is moving north-northwest at about 9 mph. It's producing maximum sustained winds of 40 mph, the hurricane center says.
[Updated 10:37 a.m. ET] Northwest Louisiana is not being hit as badly as feared. Though Isaac continues to bring heavy rains and 50-mph winds to the state - and conditions could definitely worsen this afternoon near the junction of Arkansas, Louisiana and Texas - "a dry, continental air mass has started to work into Isaac's circulation, which is limiting the rainfall amounts on the western side of the eye," reported CNN affiliate KSLA in Shreveport, Louisiana.
"This will help limit the flash flood danger, but most of theÂ ArkLaTex remains under a flash flood watch regardless," KSLA says.
[Updated 10:26 a.m. ET] New Orleans Deputy Mayor of Public Safety Lt. Col. Jerry Sneed expressed relief that the winds were dying down this morning.
â€śThis storm, it took forever to get here and now it never wants to leave,â€ť he tells CNN.
There is still some minor street flooding and about 160,000 residents are without power, so you can expect New Orleans emergency officials to â€śstart recovery ops today hard and heavy,â€ť he said.
[Updated 10:18 a.m. ET] If you're looking to help out Gulf Coast residents still reeling from Isaac's winds and downpours, we have a story on how you can lend a hand. And as always in these types of situations, CNN's Impact Your World has put together a page outlining ways to help.
[Updated 10:08 a.m. ET] Several Army Corps of Engineers trucks were loaded with generators at Camp Shelby in Hattiesburg, Mississippi, and engineers had more than 50 generators waiting to be transported to critical areas, such as hospitals, schools and other public facilities without electricity, CNN affiliate WDAM reports.
"When all the power lines go down it can take several weeks for power to be restored back to some of these outlying communities. What we can do is we can go in and put power back on to the critical places like shelters, schools, so some form of normalcy can get back to those communities, and they can get back to their lives," Sgt. 1st Class Douglas Eshenbaugh told WDAM.
[Updated 9:59 a.m. ET] CNN affiliate WDSU is reporting a hint of normalcy returning to New Orleans, as Rouse's became one of the first supermarkets in the city to open its doors following Hurricane Isaac. Company officials say all stores with electricity were instructed to open at 7 a.m. CT.
Wal-Mart, Winn-Dixie and other chains were working to open stores, too. Some smaller, independent stores opened Wednesday, WDSU reported.
[Updated 9:44 a.m. ET] In Plaquemines Parish, Louisiana, which was heavily flooded after water overtopped levees, officials plan to strategically break some levees when the wind dies down this morning, says parish President Billy Nungesser. The hope is that the operation will alleviate the flooding in the area, he said.
[Updated 9:37 a.m. ET] The Lake Tangipahoa Dam in Southern Mississippi is "expected to fail," emergency management and law enforcement officials report. Severe flooding is expected downstream along the Tangipahoa River as water levels are expected to rise.
The National Weather Service has issued a flash flood warning in the area until 11:15 a.m. CT.
[Updated 9:28 a.m. ET] More than 4,700 people spent the night in Red Cross shelters in the storm area, said Jonathan Aiken, a spokesperson for the Red Cross. The Red Cross expects the numbers to rise today because some shelters couldn't report a headcount yesterday because of weather-related communication issues.
[Updated 9:16 a.m. ET] The Storm Prediction Center has issued tornado watch until 4 p.m. CT for western and southern Alabama, the western panhandle of Florida, southeastern Louisiana and central and southern Mississippi.
The watch will replace the tornado watch for southeast Louisiana, southwest Alabama, southern Mississippi and coastal waters.
[Updated 9:11 a.m. ET]Â A tow truck driver was killed by a falling tree as he was clearing debris from a road, said Amanda Harris, deputy director of Pearl River County Emergency Management.
All of the county's major highways and roads are flooded, including Interstate 59, which was inundated with Wolf River flooding. Authorities are also concerned because Hobolochitto Creek has yet to crest and might not until at least midnight. The creek runs through Picayune, and conditions in the area are expected to worsen throughout the day.
On the flip side, Harris reported that four search and rescue operations overnight all turned out successfully.
[Updated 9:01 a.m. ET] New Orleans National Weather Service received a report of tornado on the ground on Market Street in Pascagoula, Mississippi. The storm has now moved out of the area, but a tornado warning remained in effect for Jackson County until 8 a.m. CT.
[Posted 7:48 a.m. ET] ]The National Weather Service is reporting a flash-flood emergency in Slidell, Louisiana.
The city's website reports flooding in the Old Towne area.
"Due to increasing levels in the bayous, the pumping stations are unable to pump the water out as quickly as it is rising. Until such time as those waters recede, the water that has entered Olde Towne will remain," the website says.
The weather service says that "sudden inundation up to 5 feet is possible in lower-lying areas."
"Flooding from the Bayou Bonfouca and the W-14 Canal have combined to back-fill into areas of the city," the weather service said.Read CNN's full coverage of Hurricane Isaac