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The low temperature reduced the equipment performance. The heavy rains and rapidly melting snows made the water level in the pond rise quickly.

The plant was assessed as being of “regular” risk, because the process of the plant was defined as “closed-loop”. In reality, the loop was open at two points (the Meda pond, and the new tailings pond), allowing unspecified and unmonitored amounts of cyanide to be routinely lost there to air and/or groundwater. Therefore, formal emergency response plans, planning or monitoring were inadequate considering the large quantities of hazardous materials (cyanide, hypochlorite) used close to human populations and the river system. Moreover, there were no provisions that take into consideration an uncontrollable rise of pond water level.

At the beginning, the spillage was reduced to 50 L/s and the overflow was treated with sodium hypochlorite to neutralize the cyanide. The National Mining Company REMIN collected the remaining water into its active pond located close to the Aurul pond. Then after two days, the spill has been stopped, repairing the breach using borrow material from nearby company. Timely information exchange and measures taken by the by the Romanian, Hungarian and Yugoslavian authorities have mitigated and reduced the risk and impact of the spill.

Response in Romania:
- The regional environment and water authorities immediately checked information about the breach and the spill
to determine the degree of pollution.
- These authorities ordered Aurul to stop activities and close the breakage.
- They also informed the Water and Environmental Protection Agency of Nyiregyhaza (Hungary) about the accident.
- They alerted local authorities downstream about the spill and dangers in using the river water for activities such as drinking.

Response in Hungary:
- Warnings to the public, operations at dams and ponds to protect aquifers and side branches.
- The temporary closure of the Kiskore dam (along the upper Tisza) to increase the water level and temporary closure of the water intake from the Tisza River to the town of Szolnok.

Response in Yugoslavia:
- Yugoslavian authorities for water management companies along the Tisza informed all water users to stop the operation of water supply facilities.
- Hydraulic gates prevented the spill from affecting side branches and canals along the Danube River.
- An announcement on the prohibition of fishing and fish trading was made.
- Preventive measures to protect public health, including the closing of the Belgrade water intake.

- 76 professional fishermen of Tisza river suffered from direct and indirect effects of the spill, including psychological effects.
- The health of several individuals was adversely affected after ingesting contaminated water.
- Immediate human health risk seemed to be minimal from the spill alone, but chronic health impacts due to
long-term pollution by heavy metals was deemed possible.

Three countries, Romania, Hungary and the Federal Republic of Yugoslavia, were primarily affected by the cyanide spill.
The spill has affected an area around the pond of 140,000 m2. Dead fish were recorded in Satu Mare, and eight pivately-owned wells contaminated with cyanides were found in Bozanta Mare village.
The pollution was travelling at 2.1 km/h–2.9 km/h, affecting many rivers (among which Sasar, Lapus, Somes, Tisza, FRY, and Danube) before entering the Black Sea. In total, some 2,000 km of the Danube catchment area were affected by this event.

The aquatic micro-organisms were affected by cyanide plume killing 1,500 tonnes of fish. After the cyanide plume passed, plankton and aquatic micro-organisms recovered relatively quickly (within a few days) due to unaffected water coming from upstream.

Wildlife and vegetation were destroyed over an area extending hundreds of kilometres. The Hungarian Authorities evaluated the remaining quantity of consumable fish and estimated 1,240 tons of dead consumable fish. Thousands of dead animals were found (swans, wild ducks, otters, foxes, etc.).

Direct as well as indirect economic losses were observed in agricultural and fisheries branches. The internal market as well as the export were affected due to toxicological effects and the image of products from the affected region.

The cyanide spill caused an interruption in the water supply in 24 municipalities in Romania with supplementary costs to sanitation plants and industries due to the interruption of their production processes.

In Romania, the local residents near the source of the spill were not informed as early as possible, as about ten hours were lost between the time the Baia Mare Environmental Protection Agency received notification of the spill from Aurul and the time the local Romanian Waters Authority was informed. Nonetheless, villages close to the accident site were provided with alternative water sources.

The overflown water was initially treated with sodium hypochlorite to neutralize the cyanide. The decontamination of an area of 140,000 m2 around the pond started two days after the accident.

- The water authorities started a program to monitor water quality in the Lapus and Somes rivers.
- Romania, Hungary and the Federal Republic of Yugoslavia were performing sampling and analysis for surface water, sediments and drinking water.

The breach was repaired using borrow material from nearby company.

The embankment construction was inadequate. The low temperature reduced the resistance of the structure.
Dams containing toxic waste or other liquids should be designed to have retention systems for overflow or accidents resulting from breaks in dams.

- The original Environmental Impact Assessment flawed.

- The permitting procedures were complex and inefficient - Aurul was operating in line with government permits, but there were no plans to deal with such a rise in water or to catch overflow wastewater (although it could have been foreseen).

- There were no provisions to take into account of water balance data.

- The risk classification of pond was inappropriate for monitoring purposes.

- Plants using cyanide should pay special attention to preparing for emergencies, public communication and special monitoring and inspection by authorities.

Hydrocicloning that was supposed to remove contaminants from the tailing water was unsuited for low temperature use. As a result the pond contained a higher quantity of contaminants than during normal operations at the time of the accident. A different technology more suited for low temperatures should have been used instead.

- Emergency shut off plans existed but proved insufficient.
- The early warning system, established under the Danube River Protection Convention, responded adequately to alert neighboring countries about the spill (the Romanian Principal International Alert Center (PIAC) notified the Hungarian PIAC and informed Bulgaria, Moldova, Ukraine and Yugoslavia).
- Timely information exchange and measures, taken by the Romanian, Hungarian and Yugoslavian
authorities, have mitigated and reduced the risk and impact of the spill.
- Under Romanian law, the plant and ponds, categorised as “regular” risk, did not require any special emergency planning, or contingency planning, or monitoring to detect dangerous situations. Accident plans did exist but were not sufficient. Thus, neither the company nor the local authorities had in place adequate emergency preparedness and response procedures, considering the large quantities of hazardous materials (cyanide, hypochlorite) being used close to human populations and the river system.
- The accidents at Baia Mare, Borsa (ARIA 17465) ahas contributed to the reinforcement of the European legislation on mining waste handling.