Editing Lake Erie (section)

====Eutrophication and cyanobacterial blooms====
[[File:HAZARDOUS WALK OFF HUNTINGTON BEACH ON LAKE ERIE THROUGH ALGAE AND UPROOTED TREES. HIGH WATER AND UNCONTROLLED... - NARA - 550242.jpg|thumb|upright|A 1973 photo from the U.S. [[United States Environmental Protection Agency|Environmental Protection Agency]] showing [[Coastal erosion|beach erosion]], algae, and uprooted trees as a result of environmental issues]]
[[File:Toxic Algae Bloom in Lake Erie.jpg|thumb|The green scum shown in this image taken in October 2011 is the worst [[algal bloom]] Lake Erie has experienced in decades.]]
An ongoing concern is that nutrient overloading from fertilizers and human and animal waste, known as [[eutrophication]], in which additional [[nitrogen]] and [[phosphorus]] enter the lake, will cause plant life to "run wild and multiply like crazy".<ref name=twsZ61 /> Since fewer [[wetland]]s remain to filter nutrients, and greater channelization of waterways, nutrients in water can cause algal blooms to sprout, with "low-oxygen dead zones" in a complex interaction of natural forces.<ref name=twsZ61/> As of the 2010s, much of the phosphorus in the lake comes from fertilizer applied to [[no-till farming|no-till]] soybean and corn fields, but washed into streams by heavy rains. The algal blooms result from growth of ''[[Microcystis]]'', a toxic [[Cyanobacteria|blue-green alga]] that the zebra mussels, which infest the lake, do not eat.<ref name=NYT031413 />

Periodically, a ''dead zone'', or region of low oxygen, occurs in the lake, the location of which varies. Scientists from the [[National Oceanic and Atmospheric Administration]] have been studying the lake's blue-green algal blooms and trying to find ways to predict when they are spreading or where they might make landfall; typically, the blooms arrive late each summer.<ref name=twsX412a /> This problem was extreme in the mid- and late 1960s, and the [[Angelo F. Coniglio|Lake Erie Wastewater Management Study]] conducted by the Buffalo District of the U.S. Army [[United States Army Corps of Engineers|Corps of Engineers]] determined that the eutrophication was caused by point sources such as industrial outfalls and municipal sanitary and storm sewer outfalls, as well as diffuse sources, such as overland runoff from farm and forest land. All of these sources contribute nutrients, primarily phosphorus, to the lake. Growth of organisms in the lake is then spiked to the point that oxygen levels are depleted. Recommendations were made for reducing point-source outflows, and reducing farm contributions of phosphorus by changing fertilizer usage, employing no-till farming, and other conservative practices. Many industrial and municipal sources have since been greatly reduced. The improved farming practices, which were voluntary, were followed for a while, resulting in remarkable recovery of the lake in the 1970s.<ref>{{cite web|title=International Reference Group on Great Lakes Pollution from Land Use Activities|url=http://www.ijc.org/php/publications/pdf/ID506.pdf|archive-url=https://web.archive.org/web/20131111082657/http://www.ijc.org/php/publications/pdf/ID506.pdf|url-status=dead|archive-date=November 11, 2013|pages=G–2|publisher=International Joint Commission}}</ref>

The conservation practices are not monitored and have not been kept up. One recent account suggests that the seasonal algal blooms in Lake Erie were possibly caused by runoff from cities, fertilizers, zebra mussels, and livestock near water.<ref name=twsX412a/> A second report focuses on the zebra mussels as being the cause of dead zones, since they filter so much sediment that this produces an overgrowth of algae.<ref name=twsX312a/> One report suggests the oxygen-poor zone began about 1993 in the lake's central basin and becomes more pronounced during summer, but is somewhat of a mystery why this happens.<ref name=twsX414 /> Some scientists speculate that the dead zone is a naturally occurring phenomenon.<ref name=twsZ28a/> Another report cites Ohio's [[Maumee River]] as the main source of polluted runoff of phosphorus from industries, municipalities, tributaries and agriculture, and in 2008, satellite images showed the algal bloom heading toward Pelee Island.<ref name=twsZ28a/> Two two-year, $2&nbsp;million studies are trying to understand the "growing zone", which was described as a 10-foot-thick layer of cold water at the bottom, {{convert|55|ft|m}} in one area, which stretches {{convert|100|mile|disp=sqbr}} across the lake's center.<ref name=twsX414/> It kills fish and microscopic creatures of the lake's food chain and fouls the water, and may cause further problems in later years for sport and commercial fishing.<ref name=twsX414/>

[[Algal bloom|Algal blooms]] continued in early 2013, but new farming techniques, climate change, and even a change in Lake Erie's ecosystem make phosphorus pollution more intractable.<ref>{{cite web |url=https://www.nytimes.com/2013/03/15/science/earth/algae-blooms-threaten-lake-erie.html |title=Spring Rain, Then Foul Algae in Ailing Lake Erie |date=March 14, 2013 |work=The New York Times |access-date=July 20, 2022 |archive-date=March 15, 2013 |archive-url=https://web.archive.org/web/20130315120454/http://www.nytimes.com/2013/03/15/science/earth/algae-blooms-threaten-lake-erie.html |url-status=live }}</ref> Blue-green algae ([[Cyanobacteria]]) bloom,<ref>{{cite web |url=https://www.weather.gov/cle/LakeErieHAB |archive-url=https://web.archive.org/web/20190812144803/https://www.weather.gov/cle/LakeErieHAB |archive-date=August 12, 2019 |title=Lake Erie Harmful Algal Bloom (HAB) |publisher=National Weather Service}}</ref> were problematic in August 2019. According to a news report in August, "scientists fully expect [it] to overwhelm much of western Lake Erie again this summer".<ref>{{cite web |url=https://www.toledoblade.com/local/environment/2019/08/07/summer-2019-algal-bloom-coming-strong-western-lake-erie-algae-scientists-canada/stories/20190807160 |title=Summer algal bloom coming on strong in western Lake Erie |work=Toledo Blade |last=Henry |first=Tom |date=August 7, 2019 |access-date=July 20, 2022 |archive-date=August 3, 2020 |archive-url=https://web.archive.org/web/20200803002207/https://www.toledoblade.com/local/environment/2019/08/07/summer-2019-algal-bloom-coming-strong-western-lake-erie-algae-scientists-canada/stories/20190807160 |url-status=live }}</ref> By August 12, 2019, the bloom extended for roughly {{convert|50|km}}.<ref>{{cite web |url=https://www.thestar.com/news/canada/2019/08/12/scientists-on-high-alert-as-massive-green-menace-threatens-lake-erie.html |title=Scientists on high alert as green menace threatens Lake Erie |work=Toronto Star |last=Allen |first=Kate |date=August 12, 2019 |access-date=July 20, 2022 |archive-date=November 7, 2020 |archive-url=https://web.archive.org/web/20201107231248/https://www.thestar.com/news/canada/2019/08/12/scientists-on-high-alert-as-massive-green-menace-threatens-lake-erie.html |url-status=live }}</ref> A large bloom does not necessarily mean the cyanobacteria ... will produce toxins", said Michael McKay, executive director of the Great Lakes Institute for Environmental Research <!-- (GLIER) --> at the [[University of Windsor]]. "Not enough is being done to stop fertilizer and phosphorus from getting into the lake and causing blooms," he added. Water testing was being conducted in August.<ref>{{cite web |url=https://windsorstar.com/news/local-news/large-lake-erie-algal-bloom-nearing-colchester-tested-for-toxicity |archive-url=https://web.archive.org/web/20190811140408/https://windsorstar.com/news/local-news/large-lake-erie-algal-bloom-nearing-colchester-tested-for-toxicity |archive-date=August 11, 2019 |title=Large Lake Erie algal bloom nearing Colchester tested for toxicity |work=Windsor Star |last=Hill |first=Sharon |date=August 7, 2019 |access-date=July 20, 2022}}</ref> The largest Lake Erie blooms to date occurred in 2015, exceeding the severity index at 10.5 and in 2011 at a 10, according to the NOAA. In early August, the 2019 bloom was expected to measure 7.5 on the severity index, but could range between 6 and 9.<ref>{{cite web |url=https://www.theweathernetwork.com/ca/news/article/ootw-algae-forecast-predict-large-summer-harmful-algal-bloom-for-lake-erie |title=Lake Erie's toxic algal bloom spreads, prompting warnings |last=Sutherland |first=Scott |work=The Weather Network |date=August 6, 2019 |access-date=July 20, 2022 |archive-date=August 2, 2020 |archive-url=https://web.archive.org/web/20200802234642/https://www.theweathernetwork.com/ca/news/article/ootw-algae-forecast-predict-large-summer-harmful-algal-bloom-for-lake-erie |url-status=live }}</ref> At that time, satellite images depicted a bloom stretching up to {{convert|1300|km2}} on Lake Erie, with the epicenter near [[Toledo, Ohio]].<ref>{{cite web |url=http://www.uwindsor.ca/dailynews/2019-08-07/uwindsor-researchers-test-waters-harmful-algae-bloom |archive-url=https://web.archive.org/web/20190812145246/http://www.uwindsor.ca/dailynews/2019-08-07/uwindsor-researchers-test-waters-harmful-algae-bloom |archive-date=August 12, 2019 |title=UWindsor researchers test the waters for harmful algae bloom |publisher=University of Windsor |date=August 8, 2019 |access-date=July 20, 2022}}</ref>