Despite initial concerns Sunday that some dead fish in the Yarkon River had been poisoned, indicating that divers searching for Rose Pizem's body could be harmed, there had been no real threat, according to the Yarkon River Authority and the police. The fish had died due to lack of oxygen in the water at night, a known phenomenon that occurs after a dry winter, the Authority said. Police said searches would resume in the near future. Experts who spoke with The Jerusalem Post late last week said the Yarkon's pollution levels did not pose a health risk to divers wearing full-body wet suits. "I wouldn't swim or wash in the river, but there is no pollution that can harm them," Authority head Dr. David Pargament told the Post Thursday. "As long as they are wearing wet suits, they will be fine." The Yarkon River, which runs through Tel Aviv to the sea, made international headlines a decade ago when four participants in the Maccabiah Games died after a foot bridge collapsed and they fell into it. They died as a result of complications arising from exposure to pollutants in the river. The river's quality has improved dramatically since then, Pargament said. "The water is better now than it has been, and [it's] nothing like the Kishon River," he said. The Kishon, which runs through Haifa, has been polluted by factories along its route and has been undergoing an intensive rehabilitation process over the last several years. Pollution in the Kishon made headlines several years ago when a squad of Navy divers who had trained in it displayed a higher than normal rate of cancer. The divers searching for the body haven't been looking in the Yarkon, but in the Ayalon, which merges with the Yarkon on its way to the sea, Pargament said. While there was no difference in water quality, he said, there was one significant factor differentiating the Yarkon from the Ayalon: "If you wanted to drain a section of the Ayalon, you could; in the Yarkon, you couldn't because the water rushes too fast." If you wanted to drain a section of the Ayalon, it would take about a week to do it properly and would result in no lasting ecological damage, he said. Pargament told the Post Sunday it seemed increasingly unlikely that the police would try to drain a section of the Ayalon. "It is beginning to seem like they will accomplish what they need without having to drain a section," he said. "There is the additional problem that there are fish and other organisms in the river that might have fed on the remains." While Pargament was optimistic about the river's water quality, the Israel Union for Environmental Defense's water scientist, Dr. Aharon Dotan, was more cautious. "The biggest threat is disturbing the bottom of the river and churning up all sorts of pollution, organisms and poisons," he told the Post last week. "And in certain parts of the Yarkon, it is very polluted. However, I believe that the area where they are searching is actually mostly sea water and not river water at all. There is a certain amount of risk, but in full wet suits they are not actually exposed to the water [and should be OK]."