<p><em>This gallery is part of a <a id="rrdo" title="special news series" href="http://news.nationalgeographic.com/news/clean_water_crisis.html">special news series</a> and <a id="ss6q" title="National Geographic Society initiative" href="http://environment.nationalgeographic.com/environment/freshwater/">National Geographic Society initiative</a> on freshwater.</em><strong></strong></p><p><strong>Tunde Erdelyi protects her cat from toxic sludge in her yard in <a id="ew9q" title="Devecser (map)" href="http://maps.nationalgeographic.com/map-machine#s=r&amp;c=47.08382410753432, 17.475455403327935&amp;z=12">Devecser (map)</a>, <a id="hple" title="Hungary" href="http://travel.nationalgeographic.com/travel/countries/hungary-guide/">Hungary</a>, on Tuesday.<br></strong></p><p>Triggered by a reservoir collapse Monday at the&nbsp;Ajkai Timfoldgyar alumina plant in the town of <a id="k0ex" title="Ajka (map)" href="http://maps.nationalgeographic.com/map-machine#s=r&amp;c=47.08382410753432, 17.475455403327935&amp;z=12">Ajka (map)</a>, a toxic-sludge flood has devastated seven towns, which now face contaminated water, fouled fields, and wrecked ecosystems, according to the Associated Press. Alumina, or synthetic aluminum oxide, is used in the smelting of aluminum.</p><p>Hungarian authorities report at least four people have been killed and several others are missing in the wake of Monday's fast-moving, 35-million-cubic-foot (1-million-cubic-meter) flood. Hundreds more have been injured or forced to evacuate.</p><p>(Read more: "<a id="qkxw" title="Toxic Mud Spill Latest Insult to Polluted Danube River" href="http://news.nationalgeographic.com/news/2010/10/101012-toxic-spill-hungary-danube-river-water/">Toxic Mud Spill Latest Insult to Polluted Danube River</a>.")</p><p><em>—Brian Handwerk</em></p>

Cat Saved From Toxic Sludge

This gallery is part of a special news series and National Geographic Society initiative on freshwater.

Tunde Erdelyi protects her cat from toxic sludge in her yard in Devecser (map), Hungary, on Tuesday.

Triggered by a reservoir collapse Monday at the Ajkai Timfoldgyar alumina plant in the town of Ajka (map), a toxic-sludge flood has devastated seven towns, which now face contaminated water, fouled fields, and wrecked ecosystems, according to the Associated Press. Alumina, or synthetic aluminum oxide, is used in the smelting of aluminum.

Hungarian authorities report at least four people have been killed and several others are missing in the wake of Monday's fast-moving, 35-million-cubic-foot (1-million-cubic-meter) flood. Hundreds more have been injured or forced to evacuate.

(Read more: "Toxic Mud Spill Latest Insult to Polluted Danube River.")

—Brian Handwerk

Photograph by Bela Szandelszky, AP

Photos: "Huge" Toxic Sludge Flood Hits Hungary

"This is huge," says one toxicologist of the failure of a toxic-sludge reservoir in Hungary. "If you are trapped in it, it will kill you."

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