Editing Lake Erie (section)

===Ecosystems===
[[File:Avon Lake power plant.jpg|thumb|right|A [[Fossil fuel power station|coal-fired power plant]] in [[Avon Lake, Ohio]], located on Lake Erie]]
Lake Erie has a complex ecosystem with many species in interaction. Human activity, such as pollution and maritime ship traffic, can affect this environment in numerous ways. The interactions between new species can sometimes have beneficial effects, as well as harmful effects. Some introductions have been seen as beneficial such as the introduction of [[Oncorhynchus|Pacific salmon]].<ref name=twsX312a/> Occasionally there have been mass die-offs of certain species of fish, sometimes for reasons unknown, such as many numbers of [[rainbow smelt]] in May 2010.<ref name=twsZ />

====Invasive species====
The lake has been plagued with a number of [[invasive species]], including [[zebra mussel|zebra]]<ref name=twsX312a/> and [[Quagga mussel|quagga]] mussels, the [[Round goby|goby]], and the [[grass carp]]. One estimate was that 180 invasive species are in the Great Lakes, some having traveled in ballast water in international ships.<ref name=twsZ28a/> Zebra mussels and gobies have been credited with the increased population and size of [[smallmouth bass]] in Lake Erie.<ref>[https://www.espn.com/outdoors/bassmaster/news/story?page=tourn_03_north_open_NY_erie_preview 2003–04 CITGO Bassmaster Northern Open].
BASS Communications – September 3, 2003</ref> In 2008, concerns arose that the "newest invader swarming in the Great Lakes", the [[Hemimysis anomala|bloody-red shrimp]], might harm fish populations and promote [[algae bloom|algal blooms]].<ref name=twsZ45 />

Environmentalists and biologists study lake conditions via installations such as the Franz Theodore Stone Laboratory on [[Gibraltar Island]]. The lab, which was established in 1895, is the oldest biological field station in the United States. Stone Laboratory was donated to the [[Ohio State University]] by Julius Stone in 1925 as part of the university's Ohio Sea Grant College program.<ref name=twsOhioStateUniv>Publishers: (1) Lake Erie Coastal Ohio Trail National Scenic Byway (2) Ohio Chapter of The Nature Conservancy (3) Ohio Sea Grant; Editors: Art Weber, Melinda Huntley of the Ohio Sea Grant College Program, [http://ohioseagrant.osu.edu/_documents/publications/GS/GS-025ExploretheLakeErieIslandsAGuidetoNatureandHistoryAlongtheLakeErieCoastalTrail.pdf Explore the Lake Erie Islands] {{Webarchive|url=https://web.archive.org/web/20120222214756/http://www.ohioseagrant.osu.edu/_documents/publications/GS/GS-025ExploretheLakeErieIslandsAGuidetoNatureandHistoryAlongtheLakeErieCoastalTrail.pdf |date=February 22, 2012 }}, Retrieved September 1, 2014, (see page 5) "... Lake Erie's shallow, nutrient-rich western basin and the much deeper central and eastern basins. ... The western basin ... dolomite and limestone are more durable than the softer shales ... glacier dug through the stones ... resistance from the dolomite and limestone in the western basin ..."</ref><ref name=twsZ28a /> The Great Lakes Institute of the [[University of Windsor]] has experts who study issues such as lake sediment pollution and the flow of contaminants such as [[phosphorus]].<ref name=twsZ28a/>

Other invasive species in Lake Erie include [[Bythotrephes longimanus|spiny water fleas]], [[Cercopagis pengoi|fishhook water fleas]], [[sea lamprey]], and [[white perch]]. The invasive plant species in Lake Erie consist mainly of [[Eurasian milfoil]], ''[[Trapa natans]]'' and [[purple loosestrife]].<ref>{{cite web|title=Invasive Species of Lakes Erie and Ontario|url=https://seagrant.sunysb.edu/ais/pdfs/AIS-LErieOnt.pdf|access-date=November 28, 2020|pages=G–2|publisher=Stony Brook University|archive-date=January 28, 2021|archive-url=https://web.archive.org/web/20210128141116/https://seagrant.sunysb.edu/ais/pdfs/AIS-LErieOnt.pdf|url-status=live}}</ref> The shore of the lake is also host to invasive species of the ''[[Phragmites]]'' reed genus.<ref>{{cite web|title=Great Lakes Phragmites Collaborative|url=https://www.greatlakesphragmites.net/resources/casestudies-3/lake-erie-cwma/|access-date=November 11, 2021|archive-date=November 11, 2021|archive-url=https://web.archive.org/web/20211111204642/https://www.greatlakesphragmites.net/resources/casestudies-3/lake-erie-cwma/|url-status=live}}</ref>

====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>

====Snakes====
The Lake Erie water snake, a subspecies of the northern water snake (''[[Common watersnake|Nerodia sipedon]]''), lives in the vicinity of Ohio's Put-in-Bay Harbor and had been placed on the threatened species list.<ref name=twsX12 /> By 2010, the water snake population was over 12,000 snakes.<ref name=twsX12/> While they have a nonvenomous bite, they are a key predator in the lake's aquatic ecosystem since they feed on [[Necturus|mudpuppies]], [[walleye]], and [[smallmouth bass]].<ref name=twsX12/> The snake is helpful in keeping the population of goby fish in check.<ref name=twsX12/> They mate from late May through early June and can be found in large mating balls with one female bunched within several males.<ref name=twsX13/>

====Insects and birds====
In 1999, a local TV station's [[Weather radar|Doppler weather radar]] detected millions of [[Mayfly|mayflies]] heading for Presque Isle in blue and green splotches on the radar in clouds measuring {{convert|10|mi|km|abbr=on}} long.<ref name=twsX24 /> These insects were a sign of Lake Erie's move back to health, since the mayflies require clean water to thrive.<ref name=twsX24/> Biologist Masteller of [[Pennsylvania State University]] declared the insects to be a "nice nuisance" since they signified the lake's return to health after 40 years of absence.<ref name=twsX24/> Each is {{convert|1.5|inch|abbr=on}} long; the three main species of mayflies are ''Ephemera simulans'', ''Hexagenia rigida'', and ''H. limbata''.<ref name=twsX24/> The insects mate over a 72-hour period from June through September; they fly in masses up to the shore, mate in the air, then females lay up to 8,000 eggs each over the water; the eggs sink back down and the cycle repeats.<ref name=twsX24/> Sometimes, the clouds of mayflies have caused power outages<ref name=twsX37 /> and caused roads to become slippery with squashed insects.<ref name=twsX24/> [[Zebra mussel|Zebra mussels]] filtering extra nutrients from the lake allows the mayfly larvae to thrive.<ref name=twsX37/>

[[File:Cygnus buccinator -Lake Erie, Michigan, USA-8 (1).jpg|thumb|right|[[Trumpeter swan]]s (''Cygnus buccinator'') on Lake Erie]]

Incidents of birds dying from [[botulism]] have occurred, in 2000<ref name=twsX31 /> and in 2002.<ref name=twsX26 /> Birds affected included [[grebe]]s, [[Common merganser|common]] and [[red-breasted merganser]]s, [[loon]]s, diving ducks, [[ring-billed gull]]s, and [[herring gull]]s.<ref name=twsX31/> One account suggests that bird populations are in trouble, notably the [[wood warbler]], which had population declines around 60% in 2008.<ref name=twsX312a/> Possible causes for declines in bird populations are farming practices, loss of habitats, soil depletion and erosion, and toxic chemicals.<ref name=twsX312a/> In 2006, concerns arose of possible [[avian influenza]] (bird flu) after two wild swans on the lake were found diseased, but they did not contain the [[Influenza A virus subtype H5N1|H5N1 virus]].<ref name=twsJanY311 /> Sightings of a [[magnificent frigatebird]], a tropical bird with a 2 m wingspan, happened over the lake in 2008.<ref name=twsZ34 />

====Water quality issues and restoration====
[[File:Buffalo December 2024 34 (Lake Erie).jpg|thumb|Lake Erie at Buffalo in 2024]]

Lake Erie infamously became very polluted in the 1960s and 1970s as a result of the quantity of [[heavy industry]] situated in cities on its shores, with reports of bacteria-laden beaches and fish contaminated by industrial waste.<ref name=twsZ36>{{cite news
 |title        = Troubled Waters: Pollution in the Great Lakes: Topic spans: 1959–1996
 |publisher    = CBC Digital Archives
 |year         = 2009
 |url          = http://archives.cbc.ca/environment/pollution/topics/1390/
 |access-date  = January 26, 2011
 |archive-date = December 9, 2010
 |archive-url  = https://web.archive.org/web/20101209012941/http://archives.cbc.ca/environment/pollution/topics/1390/
 |url-status   = live
}}</ref> In the 1970s, patches of the lake were declared dead because of [[industrial waste]] and sewage from runoffs; as ''[[The New York Times]]'' reporter Denny Lee wrote in 2004, "The lake, after all, is where the [[Rust Belt]] meets the water."<ref name="twsX43d"/>

Incidents occurred of the oily surfaces of tributary rivers emptying into Lake Erie catching fire: in 1969, Cleveland's [[Cuyahoga River]] erupted in flames,<ref name="twsX215">{{cite news|date=December 3, 1979|title=Environment: Comeback for the Great Lakes|magazine=Time magazine|url=http://www.time.com/time/magazine/article/0,9171,948661,00.html|archive-url=https://web.archive.org/web/20080408152157/http://www.time.com/time/magazine/article/0,9171,948661,00.html|url-status=dead|archive-date=April 8, 2008|access-date=January 24, 2011}}</ref> chronicled in a ''Time'' magazine article which lamented a tendency to use rivers flowing through major cities as "convenient, free sewers";<ref name="twsJanY214a"/> the [[Detroit River]] caught fire on another occasion.<ref name=twsX312a/> The outlook was gloomy:

{{blockquote|Each day, Detroit, Cleveland and 120 other municipalities fill Erie with {{convert|1.5|e9usgal|e6m3|abbr=off|disp=sqbr}} of "inadequately treated wastes, including nitrates and phosphates ... These chemicals act as fertilizer for growths of algae that suck oxygen from the lower depths and rise to the surface as odoriferous green scum ... Commercial and game fish—blue pike, whitefish, sturgeon, northern pike—have nearly vanished, yielding the waters to trash fish that need less oxygen. Weeds proliferate, turning water frontage into swamp. In short, Lake Erie is in danger of dying by suffocation.|''[[Time (magazine)|Time]]'' magazine, August 1969<ref name="twsJanY214a"/>|title=|source=}}

In December 1970, a federal [[grand jury]] investigation led by U.S. Attorney [[Robert Jones (Ohio lawyer)|Robert Jones]] began, of water pollution allegedly being caused by about 12 companies in northeastern Ohio.<ref>{{Cite web|url=https://rojoneswi.wixsite.com/robertjonesjdlibrary/single-post/2018/06/24/REF-51-%E2%80%9CUS-Opens-Probe-Here-on-Pollution%E2%80%9D-The-Plain-Dealer-Cleveland-Ohio-December-1970|title=REF 51 "U.S. Opens Probe Here on Pollution" The Plain Dealer, Cleveland, Ohio, December 1970.|website=Home {{!}} Robert Walter Jones J.D. Library and Archive|date=June 24, 2018|language=en|access-date=February 24, 2019|archive-date=February 25, 2019|archive-url=https://web.archive.org/web/20190225161957/https://rojoneswi.wixsite.com/robertjonesjdlibrary/single-post/2018/06/24/REF-51-%E2%80%9CUS-Opens-Probe-Here-on-Pollution%E2%80%9D-The-Plain-Dealer-Cleveland-Ohio-December-1970|url-status=live}}</ref> It was the first grand jury investigation of water pollution in the area.  The grand jury indicted four corporations for polluting Lake Erie and waterways in northeast Ohio. Facing fines were Cleveland Electric Illuminating Co., Shell Oil Co., Uniroyal Chemical Division of Uniroyal Inc. and Olin Corp.<ref>{{Cite web|url=https://rojoneswi.wixsite.com/robertjonesjdlibrary/single-post/2018/06/24/REF-52-US-Jury-Indicts-CEI-on-Ash-Dumping-in-Lake%E2%80%9D-by-Brian-Williams-The-Plain-Dealer-Cleveland-Ohio-December-1970|title=REF 52 U.S. Jury Indicts CEI on Ash Dumping in Lake" by Brian Williams, The Plain Dealer, Cleveland, Ohio, December 1970.|website=Home {{!}} Robert Walter Jones J.D. Library and Archive|date=June 24, 2018|language=en|access-date=February 24, 2019|archive-date=August 2, 2020|archive-url=https://web.archive.org/web/20200802231202/https://rojoneswi.wixsite.com/robertjonesjdlibrary/single-post/2018/06/24/REF-52-US-Jury-Indicts-CEI-on-Ash-Dumping-in-Lake%E2%80%9D-by-Brian-Williams-The-Plain-Dealer-Cleveland-Ohio-December-1970|url-status=live}}</ref> [[United States Attorney General]] John N. Mitchell gave a press conference December 18, 1970, referencing new pollution control litigation, with particular reference to work with the [[United States Environmental Protection Agency|Environmental Protection Agency]], and announcing the filing of a lawsuit that morning against the Jones and Laughlin Steel Corporation for discharging substantial quantities of [[cyanide]] into the Cuyahoga River near Cleveland.<ref>{{Cite web|url=https://www.justice.gov/sites/default/files/ag/legacy/2011/08/23/12-18-1970.pdf|title=Press Conference Attorney General John Mitchell 12-18-1970|access-date=February 24, 2019|archive-date=April 12, 2019|archive-url=https://web.archive.org/web/20190412070125/https://www.justice.gov/sites/default/files/ag/legacy/2011/08/23/12-18-1970.pdf|url-status=live}}</ref> Jones filed the misdemeanor charges in [[United States district court|district court]], alleging violations of the [[Rivers and Harbors Act of 1899|1899 Rivers and Harbors Act]].<ref>{{Cite web|url=https://rojoneswi.wixsite.com/robertjonesjdlibrary/single-post/2018/06/24/REF-53-%E2%80%9CCharges-JL-With-Pollution%E2%80%9D-AP-The-Plain-Dealer-Cleveland-Ohio-December-31st-1970|title=REF 53 "Charges J&L With Pollution" (AP) The Plain Dealer, Cleveland, Ohio, December 31st, 1970.|website=Home {{!}} Robert Walter Jones J.D. Library and Archive|date=June 24, 2018|language=en|access-date=February 24, 2019|archive-date=February 25, 2019|archive-url=https://web.archive.org/web/20190225161919/https://rojoneswi.wixsite.com/robertjonesjdlibrary/single-post/2018/06/24/REF-53-%E2%80%9CCharges-JL-With-Pollution%E2%80%9D-AP-The-Plain-Dealer-Cleveland-Ohio-December-31st-1970|url-status=live}}</ref>

Cleveland's director of public utilities Ben Stefanski pursued a massive effort to "scrub the Cuyahoga"; the effort cost $100&nbsp;million in bonds, according to one estimate.<ref name="twsJanY214a" /> New sewer lines were built.<ref name="twsJanY214a" /> Clevelanders approved a bond issue by 2 to 1 to upgrade Cleveland's sewage system.<ref name="twsJanY214a" /> Federal officials acted as well: the [[United States Congress]] passed the [[Clean Water Act]] of 1972,<ref name="twsX215" /><ref>Ashworth (1987), pp. 143–44.</ref> and the United States and Canada established [[water pollution]] limits in an international water quality agreement. The Corps' LEWMS was also instituted at that time.

The clearing of the water column is partly the result of the introduction and rapid spread of zebra mussels from Europe, which had the effect of covering the lake bottom, with each creature filtering a liter of fresh water each day, helping to restore the lake to a cleaner state.<ref name=twsX43d/> The 1972 Great Lakes Water Quality Agreement significantly reduced the dumping and runoff of phosphorus into the lake. The lake has since become clean enough to allow sunlight to infiltrate its water and produce algae and sea weed, but a dead zone persists.<ref>{{cite web|url=http://www.epa.gov/glnpo/lakeerie/eriedeadzone.html|title=Lake Erie|website=US Environmental Protection Agency|date=August 20, 2015|access-date=December 16, 2005|archive-date=January 8, 2012|archive-url=https://web.archive.org/web/20120108040642/http://www.epa.gov/glnpo/lakeerie/eriedeadzone.html|url-status=live}}</ref> There have been instances of beach closings at Presque Isle because of unexplained E. Coli contaminations,<ref name=twsX22a>{{cite news
 |author       = Don Hopey
 |title        = Mystery lurks in Lake Erie: E. coli pollution has closed beaches the past two summers; experts can't determine where it comes from or how to stop it
 |newspaper    = Pittsburgh Post-Gazette
 |date         = August 27, 2006
 |url          = http://www.post-gazette.com/pg/06239/716416-85.stm
 |access-date  = January 24, 2011
 |archive-date = November 24, 2011
 |archive-url  = https://web.archive.org/web/20111124074008/http://www.post-gazette.com/pg/06239/716416-85.stm
 |url-status   = dead
}}</ref> possibly caused by sewer water overflows after heavy downpours.

Since the 1970s environmental regulation has led to a great increase in water quality and the return of economically important fish species such as [[walleye]] and other biological life.<ref>[http://www.michigan.gov/dnr/0,1607,7-153-10366_46403_46404-145852--,00.html Recovery of Lake Erie Walleye a Success Story]. ''Michigan Department of Natural Resources.''  {{webarchive|url=https://web.archive.org/web/20121011160409/http://www.michigan.gov/dnr/0%2C1607%2C7-153-10366_46403_46404-145852--%2C00.html |date=October 11, 2012 }}</ref> There was substantial evidence that the new controls had substantially reduced levels of [[DDT]] in the water by 1979.<ref name=twsX215cc/> Cleanup efforts were described in 1979 as a notable environmental success story, suggesting that the cumulative effect of legislation, studies, and bans had reversed the effects of pollution:<ref name=twsX215cc/>

{{blockquote|The globs of oil, the multicolored industrial discharges, the flotsam from shoreline cities, the fecal and bacterial wastes are no longer dumped in the lakes in vast quantities.|''[[Time (magazine)|Time]]'' magazine, 1979<ref name=twsX215cc/>}}

Joint U.S.–Canadian agreements pushed 600 of 864 major industrial dischargers to meet requirements for keeping the water clean.<ref name=twsX215cc/> One estimate was that $5&nbsp;billion was spent to upgrade plants to treat sewage.<ref name=twsX215cc/> The change toward cleaner water has been in a positive direction since the 1970s.

There was a tentative exploratory plan to capture [[Carbon dioxide|CO<sub>2</sub>]], compress it to a liquid form, and pump it a half-mile (800 m) beneath Lake Erie's surface underneath the porous rock structure.<ref name=twsZ62>{{cite news
 |author       = Tyler Hamilton
 |title        = Risky business
 |newspaper    = The Star
 |date         = July 9, 2007
 |url          = https://www.thestar.com/business/article/233699--risky-business
 |access-date   = January 26, 2011
 |archive-url  = https://web.archive.org/web/20121023100125/http://www.thestar.com/business/article/233699--risky-business
 |archive-date = October 23, 2012
 |url-status     = dead
}}</ref> According to [[Chemical engineering|chemical engineer]] Peter Douglas, there is sufficient storage space beneath Lake Erie to hold between 15 and 50 years of liquid {{CO2}} emissions from the 4,000 megawatt Nanticoke coal plant.<ref name=twsZ62/> But there has been no substantial progress on this issue since 2007.