Water Got Into Morton’s Salt Mine Under Lake Erie. Six Gallons of It Can Dissolve a Gallon of Rock

On Thursday, 22 October, crews working a rock-salt mine some 2,000 feet beneath Lake Erie found water coming in. Morton Salt pulled every miner out, stopped underground work and told the regulators. Four days later the company said mining at its Fairport Harbor mine in Lake County, Ohio, had been shut down while it works “closely with independent experts and regulatory authorities to investigate the intrusion, evaluate its impact on the mine, and determine the next steps.” Nobody was hurt.

That is the news, and the reporting so far says nothing about a cause or a reopening date. We add none. What this article sets out is the chemistry that makes a water inflow the event every salt-mine operator plans around, the one large precedent the U.S. Geological Survey has documented, and what a lost or paused mine means for the road salt a region spreads in winter. The figures are from the reporting, from federal data and from state and university guidance; where a number is our own arithmetic, we say so.

What happened at Morton’s Fairport Harbor salt mine?

Water entered the underground workings and the mine was evacuated and closed to mining. The table puts the reported events in order. Each line is attributed to the outlet that reported it; where the reports differ on timing, we give both.

The Ohio Department of Transportation told FOX 8 that six counties receive salt from the Fairport Harbor mine: Ashtabula, Geauga, Lake, Mahoning, Portage and Trumbull. It also said it has 624,000 tons of salt in storage, about 73% of capacity, and that “We are confident we have the resources to keep Ohio roads safe this winter.”

Why is water the one thing a salt mine cannot survive?

Because the walls, roof and pillars are made of the material water dissolves. A coal or limestone mine that floods can usually be pumped out. In a salt mine, the water that comes in does not simply fill the space; unless it is already saturated, it eats the rock around it as it goes. The U.S. Geological Survey, in its report on the best-documented American case, puts it directly: “Salt mines are generally dry, but are susceptible to leaks and can become flooded if groundwater from overlying aquifers or surface water finds a way downward into the mined cavity through hundreds of feet of rock.”

The same report gives the mechanism that turns a leak into a loss: “whenever water begins to flow into a salt mine, the channels through which it flows increase in diameter as the surrounding salt dissolves.” A small inflow enlarges its own path. The larger path admits more water, which dissolves more salt. That feedback is why operators treat any water at all as an emergency, and why evacuating first and measuring second is the standard response.

How much rock can a given volume of water take? PubChem, the National Library of Medicine’s chemistry database, lists the solubility of sodium chloride as 36.0 g per 100 g of water at 25°C and its density as 2.17. On our arithmetic, 36.0 g of halite occupies about 16.6 cm³, so 100 mL of fresh water can dissolve about 16.6 mL of solid rock salt before it is saturated. That is roughly one litre of rock for every six litres of water, or a gallon of rock for every six gallons.

The last row matters as much as the first three. Water that has already passed through salt on its way down arrives as brine and does little further damage; fresh lake water or water from a freshwater aquifer is the dangerous kind. That is why the source and salinity of the inflow, which the reporting does not yet give, is the first thing investigators will want to know. Temperature counts too, but only slightly: sodium chloride is one of the few common salts whose solubility barely changes between cold and hot water.

What happened the last time a big U.S. salt mine flooded?

The precedent every report on this subject points to is the Retsof mine in Livingston County, New York. The U.S. Geological Survey summarises it in one sentence: “In 1994, the largest salt mine in North America, which had been in operation for more than 100 years, catastrophically flooded when the mine ceiling collapsed.” The mine was lost. The USGS lists the consequences on the surface: sinkholes, subsidence, cracked structures, changed stream flow, drained aquifers above the mine, and a shift in groundwater salinity that left some domestic wells unusable.

Retsof began with a roof collapse, which opened a path for water from above. The same USGS report describes the slower route, too: “Some mines leak at a slow rate for decades before a section of rock gives way.” Nothing in the Fairport Harbor reporting says which kind of event this is, or that it resembles Retsof in scale. The comparison is useful for one reason: it shows why a company and a federal regulator would stop all underground work at the first sign of water, before they know how serious it is.

How much road salt comes from mines like this?

A large share of what is spread on American roads. The USGS Mineral Commodity Summaries for 2026 put U.S. salt production at an estimated 40 million tons in 2025, with highway deicing accounting for about 37% of the salt consumed. Rock salt, the mined product, made up 38% of salt sold or used, at an average value of about $54 a metric ton at the mine. Ohio is one of the seven states that together produced about 95% of U.S. salt. The same summary records that “A regional rock salt shortage affected New York in early 2025, owing to surging demand from severe weather and limited supply.”

Road salt is bulky and cheap per ton, so it moves short distances where it can, and a region tends to lean on the mines and docks nearest to it. That is why a single mine matters to the six counties ODOT named, even when state stockpiles are healthy. This season was already tight before the inflow: our 20 October report on 2026–27 road-salt bids covered municipal prices that rose from $88.32 to $152 a ton in one Pittsburgh-area contract, and why rock salt barely melts ice below about 15°F. We do not repeat those numbers here, and this article offers no forecast of what the closure does to them.

Can a facility make the same rock salt go further?

Yes, and the techniques are the ones road agencies already use. The first is the cheapest: remove snow before treating ice. OxyChem’s deicer white paper says “Mechanical removal is the most economical and lowest impact method of snow and ice control”, and state guidance says the same. The second is pre-wetting: spraying rock salt with a liquid as it is spread, so it sticks to the pavement and starts dissolving at once instead of bouncing into the gutter.

A University of Washington review for the Washington State Department of Transportation summarises agency experience: “The pre-wetted material stays on the surface longer, produces less bounce and scatter, and resists traffic action.” It adds: “Field experience suggested typical savings of 25 to 30 percent less salt when pre-wetted salt was used.” The pre-wetting liquid can be salt brine itself; it can also be a calcium or magnesium chloride solution. The University of Minnesota’s SmartWinterSalt guidance notes that many bagged deicers are exactly this: “rock salt treated with a liquid calcium or magnesium chloride or other additives.”

The third is matching the chemical to the temperature. Rock salt works well down to about 15°F pavement temperature and very slowly below it; calcium chloride keeps working far colder because its brine stays liquid to a much lower temperature and it releases heat as it dissolves. Our calcium chloride deicer guide covers application rates. For a facility, the sensible pattern is rock salt for the bulk of the surface on the days it works, and a smaller quantity of calcium chloride for steps, ramps, docks and doorways on the coldest mornings.

What this means on a specification

For a buyer, the Fairport Harbor news is a reminder to plan for the deicer that is available, not only the one that is cheapest. The table sets the three common chlorides side by side on the properties that matter for a winter plan.

Temperatures are the Minnesota Pollution Control Agency and SmartWinterSalt practical figures, as set out in our 20 October article. They are pavement temperatures, not air temperatures, and they assume the deicer has the stated assay; check the certificate of analysis for the lot you receive.

About supply. This article reports a mine closure and road-salt figures as published by news outlets, ODOT and the USGS. Alliance Chemical does not sell bulk road salt. The article makes no claim about ours: it does not say how this closure touches the supply or price of the calcium chloride or magnesium chloride we list, where that material is made, or what it will cost later in the season. Prices are on the product pages and change with pack size.

Common questions

Why did Morton Salt close the Fairport Harbor mine?

Morton found a significant inflow of water in the underground workings on 22 October 2026, evacuated all miners and stopped underground operations. No one was injured. A federal safety order was issued the same day, and Morton announced on 26 October that mining had been shut down while it investigates with independent experts and regulators.

Where is the Morton salt mine under Lake Erie?

The mine is at Fairport Harbor in Lake County, Ohio, east of Cleveland. FOX 8 reports that its workings are about 2,000 feet below Lake Erie. The Ohio Department of Transportation says six counties receive salt from it: Ashtabula, Geauga, Lake, Mahoning, Portage and Trumbull.

Why is water so dangerous in a salt mine?

Because rock salt dissolves. Fresh water that enters can dissolve about one litre of rock salt for every six litres of water before it saturates, on our arithmetic from PubChem data, and the USGS notes that the channels water flows through widen as the salt around them dissolves, so a small leak can enlarge its own path.

Has a U.S. salt mine flooded before?

Yes. The Retsof mine in Livingston County, New York, which the USGS describes as the largest salt mine in North America, flooded catastrophically in 1994 after its ceiling collapsed. It was lost, and the USGS documents sinkholes, subsidence and changes to groundwater salinity above it. The Fairport Harbor reporting gives no indication of a similar scale.

Will the Morton mine closure cause a road salt shortage in Ohio?

The reporting does not say. ODOT told FOX 8 it has 624,000 tons of salt on hand, about 73% of capacity, and is confident it can keep roads safe this winter. Highway deicing uses about 37% of U.S. salt, per the USGS. This article makes no forecast for prices or supply.

How can I make rock salt go further this winter?

Plow or shovel first, then treat what is bonded to the pavement. Pre-wetting salt with a liquid as it is spread keeps it on the surface; a University of Washington review for WSDOT reports typical savings of 25 to 30 percent. Below about 15°F, use calcium chloride on critical areas instead of more salt.

What we stock

Calcium Chloride Technical Grade

2 and 5 lb packs; 50 lb bags and multi-bag lots. For cold-morning deicing, pre-wetting brine, dust control and drying.

Magnesium Chloride Hexahydrate FCC, USP GRADE

A high-purity grade for formulation and lab work; priced for that, not for spreading on a lot.

Key numbers and sources