Is water quality more important than quantity at the Sea of Galilee?
As heavy rains raise the level of the lake, a leading scientist has warned that the amount of water is not the most important metric.
By EYTAN HALON
As heavy rainfall continues across northern and central Israel in the coming days, television meteorologists will excitedly hail the long-awaited precipitation filling up the shrinking Sea of Galilee.The water level of the lake swelled by approximately six centimeters between Wednesday and Thursday alone, according to figures published by the Water Authority, leaving the nation's largest freshwater lake approximately 1.23 meters above the problematic "bottom red line."But could it be that the importance of tracking the Sea of Galilee water levels is significantly overstated today?According to Prof. Moshe Gophen, a leading scientist at MIGAL – Galilee Research Institute in Kiryat Shmona, the "quality of the water is much more important than the quantity." That is especially the case, he adds, now that the majority of Israel's domestic water needs are answered by water supply from advanced desalination plants."The measurement of the water level is one parameter which is highly understandable for the public - we describe it in centimeters and quantities," said Gophen, who spent his early life in Kibbutz Afikim, near the southern shore of the Sea of Galilee. "When you talk about nitrogen and phosphorous, and good and bad algae, the public does not understand it very well. You cannot put it on television."The most critical parameter for the monitoring of water quality, Gophen says, is the composition of algae - microscopic organisms - in the Sea of Galilee.In recent decades, as a byproduct of the "very successful management" of the Hula Valley, there has been a decline of nitrogen supply into the nearby lake, leading to the decline of "good" algae and the rise of toxic cyanobacteria, also known as blue-green algae.Gophen's new book, Different Kinneret published by Glilit Books, details the fundamental changes that have impacted the Sea of Galilee ecosystem over the past 25 years and, notably, the negative affect of the new bacteria on the water quality of the lake."I realized that under low water levels, the water quality is better. The explanation is very simple because lower river discharge and water inflows means lower imports of pollutants from the drainage basin," said Gophen, who served as director of the Kinneret Limnological Laboratory for six years."Due to insufficient nitrogen supply from external sources, the algae which needed this nitrogen for normal life suffered and declined. But there is no open space in the lake - If one algae declines, another arrives instead."Scientists were previously able to accurately predict seasonal blooms of "good" freshwater peridinium algae, which did not produce any toxins and were comparatively straightforward to remove from the water. The more recent blue-green algae have now become dominant due to their rare and special ability to gain nitrogen from the atmosphere."These blue-green bacteria are not good for the quality of water supply. The negative impact of the bacteria is that you cannot make precise predictions regarding when they will appear as a heavy bloom. Also, removing them in order to improve water for supply is much more difficult and complicated in comparison with the good algae," Gophen said."Most important is that the blue bacteria produces toxins. If the toxin concentration is very high, it is risky for the health of humans and all organisms."In order to improve water quality in the lake, Gophen highlights two potential solutions. The first suggestion is to introduce exotic silver carp fish into the lake due to their ability to consume blue-green bacteria. The fish, native to China, can also improve fishermen income in the area.The second solution to improve water quality requires introducing desalinated water from the Mediterranean Sea into the Sea of Galilee, while simultaneously withdrawing water rich with pollutants or nutrients."What can we do with the water we remove from the lake? We can use the water to enhance supply to regions of Israel which suffer from insufficient water for agricultural processes," said Gophen, highlighting the Upper Galilee and the Jordan Valley.Emphasizing that the lake will not disappear, due to restrictions on pumping once waters decline to a certain level, Gophen says his new book aims to increase understanding among the public of the importance of water quality."Decision-making is located in the hands of the director of the Water Authority, which is part of the Ministry of Energy. He should be listening to everybody and making his own decisions regarding water levels," said Gophen. "As part of the Hanukkah miracle, I hope that rain will continue until Purim, and even until Passover."