Update: This story has been updated to reflect the current number of barges that have sunk in the Ohio River.

After seven barges carrying coal sank recently in the Ohio River near downtown Louisville, many are wondering: How will this affect the river and our drinking water?

The U.S. Coast Guard is working with the Army Corps of Engineers and Tennessee Valley Towing, the company that owns the vessel that was pushing the barges, to recover the sunken barges as well as the two others that are still stuck on the river.

As recovery work continues, here is what we know about the presence of coal in the Ohio River and potential environmental concerns following the incident:

Is my drinking water safe?

The spill is not expected to affect Louisville's drinking water.

Louisville's intake facility is located upstream from the where the barges sank and is not expected to be impacted by the coal spill, said Louisville Water spokeswoman Kelley Dearing Smith.

Evansville officials are monitoring the situation, as the city is located downstream from where any coal could float, said Lisa Cochran, spokeswoman for the Ohio River Valley Water Sanitation Commission. The commission notified Evansville Water and Sewer Utility and Louisville Water Co. of Tuesday's incident and the presence of coal on the barges.

Allen Mounts, director of Evansville Water and Sewer Utility. said lab personnel are paying attention to the water quality in the Ohio River near Evansville following the incident closer to Louisville..

But given the "fast-moving pace of the river and that it is at a high level," Mounts said they are not too concerned about potential harm or contamination to the city's water supply.

The Kentucky Department for Environmental Protection was also notified of the incident in order "to ensure water stays clean" given the presence of coal on the barges, said Lt. Cmdr. Michael Metz with the U.S. Coast Guard Sector Ohio Valley.

Related:What's next for the sunken Ohio River coal barges? Here's what we know

What are potential impacts to the Ohio River?

Coal contains toxic elements such as arsenic as well as heavy metals such as lead and mercury.

While an investigation is ongoing and effects on the river are not yet known, several experts and officials do not believe the amount of coal spilled in the Ohio River this week is enough to cause detrimental effects to the river.

The recent incident is "certainly unfortunate but not the largest concern" facing the Ohio River, said Jason Flickner, director of Lower Ohio River Waterkeeper, a nonprofit group that works to protect the river.

Flickner said reports of barges spilling coal into the Ohio River pop up each year, but the practice of mercury dumping or sewage disposal is a bigger issue for the health of the waterway right now.

Rich Cogen, executive director of the Ohio River Foundation, said coal in its solid form is "less concerning relative to water quality" than coal ash or coal waste that has been burned or combusted.

The presence of coal in the river can, however, be "somewhat concerning" to riverbed aquatic habitats and marine life, Cogen said.

You may like:19 fascinating people in Louisville in 2019 – plus 3 to keep an eye on

A similar incident involving coal barges happened earlier this year in Pennsylvania. In May, 15 coal barges broke loose and two barges sank and spilled coal into the Monongahela River.

However, the Pennsylvania Department of Environmental Quality determined the spilled coal would not present a risk to water downstream from the spill.

Research on waterway contamination resulting from coal spills has not been conclusive over the years, but some studies have suggested that coal ash could harm marine life.

In 2015, the Ohio River was identified by ORSANCO as leading the nation's waterways in receiving industrial pollution.

What about damage to the bridge or dam?

Officials said they had not observed any damage to the Clark Memorial Bridge or McAlpine Locks and Dam on the Ohio River as a result of this week's incident.

Shawn Kenney, assistant operations manager for the Army Corps of Engineers Louisville District, said one of the sunken barges is blocking a gate from closing at the dam, which could be problematic given higher-than-usual river levels right now.

If the barge keeps blocking the dam gate, vessel traffic on the river could be stopped if it isn't deep enough for watercraft to pass through, Kenney said.

The Coast Guard is allowing vessel traffic on the Ohio River only during daylight hours and with an assist vessel, Metz said.

Read this:With 2018 soon over, Louisville on the cusp of breaking rainfall record

How much coal was on the barges?

While official figures have not been released, Metz said each barge involved in this recent Ohio River incident typically holds between 1,500 and 1,750 tons of coal.

That means at least 10,500 tons of coal on the seven sunken barges likely spilled into the Ohio River.

The coal was mined in western Kentucky and headed toward LG&E and KU's Trimble County and Ghent power plants, said LG&E spokeswoman Natasha Collins. Collins said operations were not affected at either plant as a result of the lost coal.

Transporting coal by river barges has increased in recent years, according to federal data.

In 2017, 12 percent of coal shipped in the United States was transported by river barge, an increase over the 7 percent of coal transported by river barge in 2008, according to the U.S. Energy Information Administration.

Will the coal just stay in the river?

It is not yet known if crews will be able to recover the coal that spilled into the water, Metz said.

Officials have been assessing how to remove each barge from the river and hope to start salvaging the barges "as safely and as soon as possible," Metz said.

It's not yet clear how long the recovery process could take.

But Metz said crews would typically pull the two barges stuck at the dam first and then attempt to recover the seven barges that capsized. Kenney said a private contractor will salvage the sunken barges.

"We are working around the clock to fix this," Metz said.

Previously:Barge clips wall at Waterfront Park, causing 'significant damage'

Who is responsible for paying for the cleanup?

Typically the towing company would pay for any costs associated with the accident and cleanup, but Metz said details surrounding cost and responsibility are still being determined.

Metz said Tennessee Valley Towing has retained two salvage teams to recover the sunken barges.

Sarah Perry McGee, general counsel for James Marine Inc., the parent company of Tennessee Valley Towing, told the Courier Journal in an email that the towing company "is cooperating with all governmental agencies."

The state of Kentucky has the ability to punish companies in certain cases for violations such as discharging pollutants and degrading the waters of the commonwealth. Each violation can carry fines up to $25,000 a day.

The Kentucky Division of Water is monitoring the situation but is mostly letting the Coast Guard handle the recovery process and initial investigation into the crash, said Peter Goodmann, director of the Division of Water.

The Division of Water will complete an assessment eventually to determine if "we need to take action" against Tennessee Valley Towing, Goodmann said.

"At this point, we don't see an immediate long-term threat to aquatic life or water quality," he said.

See also:Here's the Saturday procession route to honor officer Deidre Mengedoht

Goodmann said the state could fine the towing company if it is determined to have violated water quality standards.

In January, Kentucky issued three notices of violation to a different towing company, Southern Towing, that owned a barge carrying fertilizer that spilled into the river near Cincinnati. The violations related to discharging pollutants and degrading the waters of the commonwealth.

The spill happened in December 2017, when a barge cracked in half and released 467,000 gallons of fertilizer into the river that headed toward Louisville.

In response, Louisville Water closed its drinking water intakes to safeguard the city's water supply, and water sampling began almost immediately. Scientists found higher-than-normal levels of ammonium and nitrogen, ingredients of the fertilizer.

While no large losses of aquatic life were observed, local scientists believe the chemicals caused the deaths of some fish and freshwater mussels.

The Kentucky Energy and Environment Cabinet ended up fining Southern Towing $25,000, John Mura, the cabinet's communications director, said in an email.

For its role in the fertilizer spill, Southern Towing is also paying ORSANCO and the Foundation for Ohio River Education $100,000 as part of a supplemental project that teaches people to become environmental stewards, Mura said.

Reach Billy Kobin at bkobin@courierjournal.com or 502-582-7030.