Mokoan Dam

{{Short description|Former dam, now wetlands, in Victoria, Australia}} {{Use dmy dates|date=July 2019}} {{Use Australian English|date=May 2026}} {{Infobox dam | name = Mokoan Dam | name_official = | image = Lake-Mokoan-aerial.jpg | image_size = 240 | image_caption = Aerial view of the reservoir in 2008,<br/>prior to its decommissioning in 2011 | image_alt = | location_map = Victoria | location_map_size = 240 | location_map_caption = Location of the former dam in [[Victoria, Australia|Victoria]] | location_map_alt = | mapframe = no | coordinates = {{coord|-36.4811592102051|146.020690917969|type:landmark_region:AU-VIC|format=dms|display=it}} | country = Australia | location = near {{VICcity|Benalla}}, [[Victoria, Australia|Victoria]] | purpose = {{ubl|[[Water supply]]|[[Irrigation]]}} | status = D | construction_began = 1960s | opening = 1971 | demolished = 2011 {{small|(decommissioned)}} | cost = | builder = | designed_by = | owner = | operator = [[Goulburn–Murray Water]] {{small|(as a dam)}} | dam_type = F | dam_crosses = {{ubl|Winton Swamp|''[[off-stream reservoir|off-stream]]''}} | dam_height_foundation = {{cvt|11|m}} | dam_height_thalweg = | dam_length = {{cvt|7500|m}} | dam_elevation_crest = | dam_width_crest = | dam_width_base = | dam_volume = {{cvt|956|e3m3}} | spillway_count = | spillway_type = [[Spillway#Types|Uncontrolled]] | spillway_length = | spillway_capacity = {{cvt|255|m3/s}} | spillway_volumetric_flow_rate = | spillway_type2 = | spillway_length2 = | spillway_capacity2 = | spillway_volumetric_flow_rate2 = | spillway_type3 = | spillway_length3 = | spillway_capacity3 = | spillway_volumetric_flow_rate3 = | res_name = | res_capacity_total = | res_capacity_active = | res_capacity_inactive = | res_catchment = | res_surface = | res_max_length = | res_max_width = | res_max_depth = | res_elevation = | res_tidal_range = | lower_dam_type = | lower_dam_crosses = | lower_dam_height_foundation = | lower_dam_height_thalweg = | lower_dam_length = | lower_dam_elevation_crest = | lower_dam_width_crest = | lower_dam_width_base = | lower_dam_volume = | lower_spillway_count = | lower_spillway_type = | lower_spillway_length = | lower_spillway_capacity = | lower_spillway_volumetric_flow_rate = | lower_spillway_type2 = | lower_spillway_length2 = | lower_spillway_capacity2 = | lower_spillway_volumetric_flow_rate2 = | lower_spillway_type3 = | lower_spillway_length3 = | lower_spillway_capacity3 = | lower_spillway_volumetric_flow_rate3 = | lower_res_name = | lower_res_capacity_total = | lower_res_capacity_active = | lower_res_capacity_inactive = | lower_res_catchment = | lower_res_surface = | lower_res_max_length = | lower_res_max_width = | lower_res_max_depth = | lower_res_elevation = | lower_res_tidal_range = | plant_name = | plant_coordinates =  | plant_operator = | plant_commission = | plant_decommission = | plant_type = | plant_hydraulic_head = | plant_turbines = | plant_pumpgenerators = | plant_pumps = | plant_capacity = | plant_capacity_factor = | plant_efficiency = | plant_storage_hours = | plant_annual_gen = | plant_annual_gen_year = | website = | extra = {{Infobox body of water | embed = yes | name = '''Winton Wetlands''' | native_name = | other_name = ''Lake Mokoan'' {{small|(former)}}  | image = Winton Wetlands, VIC.jpg | alt = | caption = Dead [[Eucalyptus camaldulensis|Murray River Red Gum]]s<br/>in the wetlands, 2021 | image_bathymetry = | alt_bathymetry = | caption_bathymetry =  | location = Northern Victoria | group = | coordinates = {{coord|36|30|22|S|146|5|46|E|region:AU-VIC_type:waterbody|display=inline|format=dms}} | type = [[Wetland]]s | etymology = | part_of = | inflow = {{hlist|Seven Mile Creek|Winton Creek|Eleven Mile Creek|Show Creek|Taminick Creek|Mokoan Inlet Channel {{small|(catchment flooding)}}}} | rivers = | outflow = {{hlist|''Evaporation''|Broken Creek {{small|(catchment flooding)}}}} | oceans = | catchment = {{cvt|339|km2}} | basin_countries = | agency = | designation = | date-built =  | engineer = | date-flooded =  | length =  | width =  | area = {{ubl|{{cvt|9000|ha}} {{small|(wetlands site)}}|{{cvt|789.1|ha}} {{small|(as a reservoir)}}{{efn|Although, flooded area is believed to total {{cvt|3000|ha}}.<ref name=MP/>{{rp|60}}}}}} | depth =  | max-depth = {{cvt|7.3|m}} | volume = {{cvt|365|GL|acre.ft}} {{small|(as a reservoir)}} | residence_time = | salinity = | shore =  | elevation = {{cvt|165|m}} {{AHD}} | temperature_high =  | temperature_low =  | frozen = | islands = | islands_category = | sections = | trenches = | benches = | cities =  | pushpin_map = | pushpin_label_position = | pushpin_map_alt = | pushpin_map_caption = | mapframe =   | website = {{url|wintonwetlands.org.au}} | reference = <ref name=ANCOLD/><ref name=MP/> }} }} The '''Mokoan Dam''' is a [[Project commissioning|decommissioned]] earth-filled [[embankment dam]] across Winton Swamp, located approximately {{convert|7|km}} north-east of [[Benalla]], in northern [[Victoria, Australia|Victoria]], Australia. Completed in 1971, the resultant [[reservoir]], '''Lake Mokoan''', was also fed through [[off-stream reservoir|off-stream]] storage by water diverted from the [[Broken River (Victoria)|Broken River]] and Hollands Creek into the Winton and Green swamps{{spaced endash}}a former [[wetland]]s system. Operated by [[Goulburn–Murray Water]], the dam was a source of [[water supply|supply]] of [[potable water]] and [[irrigation]].<ref name=ANCOLD/>

Ongoing environmental issues{{spaced endash}}including [[algal bloom]]s, significant water loss from evaporation, costs of operating the reservoir as a water supply, and dam safety upgrade costs{{spaced endash}}caused frequent interruptions to supply due to, in part, not completing the intended works downstream of the reservoir making the reservoir inefficient.<ref name="Guide">{{cite web |url=https://www.water.vic.gov.au/__data/assets/pdf_file/0029/671951/decommissioning-and-repurposing-dams-a-guide-for-dam-owners.pdf |title=Decommissioning and repurposing dams - A guide for dam owners |work=Department of Energy, Environment and Climate Action |publisher=[[Victorian Government]] |date=September 2024 |access-date=2026-05-18 |isbn=978-1-76136-936-0 |page=17 }}</ref> In 2004, the [[Victorian Government]] decided to decommission the dam<ref name="Fact Sheet">{{cite web |url=https://vgls.sdp.sirsidynix.net.au/client/search/asset/1294958 |title={{Title case|SECURING OUR WATER FUTURE TOGETHER}}: Fact Sheet 6: Returning water to our rivers – Lake Mokoan |work=Department of Sustainability and Environment and Department of Primary Industries |publisher=[[Victorian Government]] |date=June 2004 |access-date=2026-05-18 |issn=1449 7549 }}</ref> and transform the former Lake Mokoan into the '''Winton Wetlands'''. Decommissioning work was completed between 2009 and 2011, with estimates that the new wetlands may take between 30–40 years,<ref name=MP/>{{rp|73}} or up to 100 years<ref name="CT 1991"/> to return to its natural conditions.

== Dam and reservoir overview == === Dam === Located on the traditional lands of the [[Yorta Yorta]] people,<ref name=CSU/> construction of the former dam began in the late 1960s and was completed in 1971.<ref name="CT 1971">{{cite news |url=http://nla.gov.au/nla.news-article110681323 |title=Dam open |newspaper=[[The Canberra Times]] |volume=46 |issue=12,937 |date=9 October 1971 |access-date=8 March 2017 |page=9 |via=Trove. [[National Library of Australia]] |quote=''...The third largest reservoir in Victoria (land area, not water volume), Lake Mokoan, near Benalla, was officially opened by the Minister of Water Supply, Mr Dunstan, today…''}}</ref><ref>{{cite web |url=http://www.g-mwater.com.au/browse.asp?ContainerID=mokoan |author= |title=Lake Mokoan |work=[[Goulburn-Murray Water]] |access-date=2010-01-17 |archive-url=https://web.archive.org/web/20091017095643/http://www.g-mwater.com.au/browse.asp?ContainerID=mokoan |archive-date=17 October 2009 |url-status=dead }}</ref> The former [[earth-filled dam]] wall was {{convert|11|m}} high and {{convert|7500|m}} long. When full, Lake Mokoan had a storage capacity of {{convert|365|GL|acre.ft|lk=on}} and covered {{convert|789.1|ha}}, drawn from a [[drainage basin|catchment area]] of {{convert|339|km2}}. The [[Spillway#Types|uncontrolled spillway]], prior to its decommissioning, had a discharge capacity of {{convert|255|m3/s}}.<ref name=ANCOLD>{{cite web |title=Register of Large Dams Australia-2015 |date=January 2022 |access-date=2026-03-05 |url=https://ancold.org.au/information-resources/dams-information/ |work=[[ANCOLD]] |format=[[Microsoft Excel|Excel]]. Requires download. Row 354}}</ref>

=== Reservoir === Following its flooding, approximately 150,000<ref name=CSU>{{cite press release |author=Finlayson, Max |url=https://news.csu.edu.au/opinion/the-winton-wetlands-why-its-restoration-provides-a-sense-of-hope |title=The Winton Wetlands: why its restoration provides a sense of hope |publisher=[[Charles Sturt University]] |date=2010-06-09 |access-date=2026-05-18}}</ref> to 200,000 [[Eucalyptus camaldulensis|Murray River Red Gum]]s<ref>{{cite web |url=https://www.airseedtech.com/projects/restoring-river-red-gums-at-winton-wetlands |title=Restoring River Red Gums at Winton Wetlands |work=Air Seed |date=n.d. |access-date=2026-05-18 }}</ref> within the former swamplands and surrounding plains soon died.<ref name=MP/>{{rp|60}} The large<ref name="CT 1971"/> and shallow {{convert|7.3|m|ft|adj=mid|-deep}}<ref name="Guide"/> lake had a very high surface area to volume ratio, resulting in extreme water loss through evaporation, and there were frequent toxic algal blooms that required regular closures for recreation activities and caused livestock to become ill and die.<ref>{{cite journal |author1=Carbis, C. R. |author2=Waldron, D. L. |author3=Mitchell, G. F. |author4=Anderson, J. W. |author5=McCauley, I. |url=https://www.researchgate.net/profile/Graham-Mitchell-2/publication/15716326_Recovery_of_hepatic_function_and_latent_mortality_in_sheep_exposed_to_blue_green_algae_Microcystis_aeuruginosa/links/58b61076aca27261e5166298/Recovery-of-hepatic-function-and-latent-mortality-in-sheep-exposed-to-blue-green-algae-Microcystis-aeuruginosa.pdf |title=Recovery of hepatic function and latent mortality in sheep exposed to blue green algae "Microcystis aeuruginosa" |journal=Veterinary Record |volume=137 |number= |date=1995 |access-date=2026-05-18 |pages=12-15 |via=ResearchGate.net }}</ref><ref>{{cite news |title=Scientists warn on toxic algae |author=O'Neill, Graeme |newspaper=[[The Age]] |date=4 December 1991 |page=5 |url=http://newsstore.fairfax.com.au/apps/viewDocument.ac?page=1&sy=age&kw=mokoan&pb=all_ffx&dt=enterRange&dr=1month&sd=04%2F12%2F1991&ed=04%2F12%2F1991&so=relevance&sf=text&sf=headline&rc=10&rm=200&sp=adv&clsPage=1&docID=news911204_0207_7128 |access-date=March 8, 2017}}</ref><ref>{{cite news |title=Blue-green algae outbreak likely to be worst on record |author=Neales, Sue |newspaper=[[The Age]] |date=4 January 1995 |page=3 |url=http://newsstore.fairfax.com.au/apps/viewDocument.ac?page=1&sy=age&kw=mokoan&pb=all_ffx&dt=enterRange&dr=1month&sd=04%2F01%2F1995&ed=04%2F01%2F1995&so=relevance&sf=text&sf=headline&rc=10&rm=200&sp=adv&clsPage=1&docID=news950104_0079_0124 |access-date=March 8, 2017}}</ref><ref>{{cite web |url=http://www.lakemokoan.com/environment.htm |title=Return to wetland |work=lakemokoan.com |date= |access-date= |archive-url=https://web.archive.org/web/20120317083835/http://www.lakemokoan.com/environment.htm |archive-date=2012-03-17 |url-status= }}</ref>

It was initially planned that the East-Goulburn Channel, in conjunction with water supplied from the {{convert|40.4|GL|acre.ft|adj=on}} [[Lake Nillahcootie]] collect water during winter and high rainfall events for diversion into Lake Mokoan. The East-Goulburn Channel was never completed. Additionally, minor flooding problems limited the effectiveness of this strategy. The [[1979–1983 Eastern Australian drought|Eastern Australian drought]] caused Lake Mokoan to completely drain in 1983, cessation of flood mitigation strategies in 1992, major flooding in the area in 1993, and political pressure to return environmental flows to the [[Snowy River]] were cited as reasons to evaluate the future of the reservoir.<ref>{{cite web |author=Skykes, Bill |author-link=Bill Sykes |url=https://wintonwetlands.org.au/app/uploads/2018/02/Interpretive-Signage-WW.pdf |title=Some thoughts of Mokoan |work=wintonwetlands.org.au |date=February 2018 |access-date=2026-05-18 |page=1 }}</ref>

== Decommissioning of the dam and reservoir == Although a locally popular recreational destination, after intensive studies,<ref name="Fact Sheet"/> in 2004 the Victorian Government decided to decommission the dam, canals, and reserve to restore the landscape to a natural wetland and woodland ecosystem. Planning for the decommissioning began in 2004<ref>{{cite news |url=http://www.abc.net.au/pm/content/2004/s1164058.htm |title=Man made lake to be released into Murray River |author=Haxton, Nance |date=July 28, 2004 |publisher=[[ABC Radio (Australian network)|ABC Radio]] |access-date=2010-01-17 |work=[[PM (radio program)|PM]] }}</ref> and work started in 2009.<ref>{{cite news |url=http://www.abc.net.au/news/stories/2009/03/30/2529458.htm |archive-url=https://web.archive.org/web/20090401071508/http://www.abc.net.au/news/stories/2009/03/30/2529458.htm |url-status=dead |archive-date=1 April 2009 |title=Lake Mokoan decommissioning delayed |work=[[ABC News (Australia)|ABC News]] |location=Australia |date=March 30, 2009 |access-date=2010-01-17 }}</ref> The restoration effort was expected to take between 30–40 years,<ref name=MP/>{{rp|73}} or up to 100 years.<ref name="CT 1991">{{cite news |author=O'Neill, Graeme |url=http://nla.gov.au/nla.news-article122372866 |title=Folly of building dams in a rush or against advice |newspaper=[[The Canberra Times]]: {{Title case|MIDWEEK MAGAZINE}} |volume=65 |issue=20,556 |date=24 July 1991 |access-date=8 March 2017 |page=24 |via=Trove. [[National Library of Australia]] }}</ref>

Decommissioning the lake was expected to allow the rebalancing of {{convert|44|GL|acre.ft}} per year to the Broken, [[Goulburn River|Goulburn]], Snowy, and [[Murray River|Murray]] rivers<ref name="Fact Sheet"/> and irrigation network, with environmental and economic benefits to both upstream and downstream areas.<ref>{{cite web |url=http://www.gbcma.vic.gov.au/downloads/FloodplainManagement/Flow-Regime-Information-Bulletin.pdf |title=Flow Regime Fact Sheet |date=July 2006 |work=Goulburn Broken Catchment Management Authority |url-status=dead |archive-url=https://web.archive.org/web/20060819170543/http://www.gbcma.vic.gov.au/downloads/FloodplainManagement/Flow-Regime-Information-Bulletin.pdf |archive-date=2006-08-19}}</ref> Instead of evaporating, the saved water would be redirected or pumped overland from the upstream Lake Nillahcootie and [[Lake Eildon]]. It was claimed that {{convert|30|GL|acre.ft}} of the former lake would be released into the Murray River system, and another {{convert|20|to|21|GL|acre.ft}} released into the Snowy River.<ref>{{cite report |author=Jeffrey, David R. |url=https://ancold.org.au/product/2011-mokoan-return-to-wetland-project/ |title=Mokoan – Return to Wetland Project |work=[[ANCOLD]] |date=2011 |access-date=2026-05-18 |format=abstract }}</ref><ref>{{cite news |url=https://www.abc.net.au/news/2004-07-29/water-boost-for-snowy-river/2016984 |title=Water boost for Snowy River |work=[[ABC News (Australia)|ABC News]] |location=Australia |date=29 July 2004 |access-date=2026-05-18 }}</ref> Completed by Goulburn-Murray Water, the decommissioning involved a {{convert|10|m|ft|adj=mid|-wide}} breech in the embankment, as well as the dismantling and infill of various channels.<ref>{{cite report |author=Office of Water |url=https://www.planning.vic.gov.au/__data/assets/pdf_file/0031/698116/2007-5-Referral-form.pdf |title=Environment Effects Act Referral – Lake Mokoan Decommissioning & Mid Murray Storage Project |work=Planning Victoria |publisher=[[Victorian Government]] |date=2007 |access-date=2026-05-18 |page=2 }}</ref>

== Winton Wetlands == In 2010, the former Lake Mokoan, covering {{convert|3000|ha}} was reformed into [[ephemeral]] wetlands and the area, totalling {{convert|9000|ha}}, classified as the ''Winton Wetlands Reserve''.<ref name=MP>{{cite web |url=https://wintonwetlands.org.au/app/uploads/2018/02/Winton_Wetland_Masterplan_Geography_highlighted.pdf |title=Master Plan: Final Draft |work=Winton Wetlands Committee of Management |date=31 August 2012 |access-date=2026-05-18 }}</ref>{{rp|60}} It is the largest wetlands restoration project in the [[Southern Hemisphere]] and, in 2013, it became the first site outside the United States to be classed as a ''Wetland of Distinction'' by the [[Society of Wetland Scientists]],<ref name=CSU/> and the only site in Australia. The wetlands contains 180 native species of birds, fish, frogs, reptiles, bats and plants; and nearly 30 species that are listed as endangered or at risk.<ref>{{cite web |url=https://sws.org/members/?id=81379949 |title=Winton Wetlands |work=[[Society of Wetland Scientists]] |date=2013 |access-date=2026-05-18 |format=Search: Australia }}</ref>

The Victorian Government initially committed $1 million to assist with the restoration of the wetlands;<ref name="Fact Sheet"/> subsequently increased to $17 million.<ref name=CSU/> Managed by a local management committee, restoration of the landscape and development of tourism commenced,<ref>{{cite web |title=Project Ethos |url=https://wintonwetlands.org.au/about/winton-wetlands-project/ethos/ |website=Winton Wetlands |date=n.d. |access-date=2019-08-20}}</ref> with a visitor's centre and cafe, interpretive information signs, four campgrounds, picnic areas, public toilet blocks, {{convert|60|km}} of roads, bush walks, {{convert|30|km}} of cycling trails, and artworks celebrating the landscape and its history. Camping, boating, and fishing facilities were made accessible.<ref name="AR 2023" />

{{as of|2023}}, environmental restoration averaged {{convert|200|ha}} per year, and plants regenerating and wildlife populations were increasing on the site.<ref name="AR 2023">{{cite web |url=https://wintonwetlands.org.au/wp-content/uploads/2024/07/Winton-Wetlands-Annual-Report-22-23_6_WEB.pdf |title=Annual Report: 2022-2023 |work=Winton Wetlands Committee of Management |date=May 2024 |access-date=2026-05-18 }}</ref> However, in July 2025 it was reported that the management committee was unable to establish a sustainable business model for the wetlands, and parts of the site were closed to the public.<ref>{{cite news |url=https://www.abc.net.au/news/2025-07-08/winton-wetlands-temporary-closure-sparks-environmental-concerns/105503234 |title=Winton Wetlands temporary closure sparks concern pest numbers could 'explode' |work=[[ABC News (Australia)|ABC News]] |location=Australia |date=8 July 2025 |access-date=2026-05-18 }}</ref>

== See also == {{stack|{{Portal|Victoria|Water|Environment|Wetlands}}}} * [[:Category:Lakes of Victoria (state)|List of lakes of Victoria]] * [[List of reservoirs and dams in Australia#Victoria|List of reservoirs and dams in Victoria]] * ''[[A Directory of Important Wetlands in Australia]]''

== Notes == {{noteslist}}

==References== {{reflist}}

== External links == * {{cite web |url=https://wintonwetlands.org.au |title=Winton Wetlands official website}} ** {{cite web |url=https://wintonwetlands.org.au/wp-content/uploads/2017/08/Master_Plan_Summary_Sheet_FINAL-1.pdf |title=Master Plan Summary Sheet |work=Winton Wetlands Committee of Management |date=August 2017 |access-date=2026-05-18 }} * {{cite web |url=https://www.bsfg.org.au |title=Home page |work=Benalla Sustainable Future Group |date=n.d. |access-date=2026-05-18 }}

{{Rivers of the Goulburn Broken catchment of the Murray-Darling basin}} {{Lakes of Victoria |state=collapsed}}

{{DEFAULTSORT:Mokoan}} [[Category:1971 establishments in Australia]] [[Category:2011 disestablishments in Australia]] [[Category:Dams completed in 1971]] [[Category:Dams in the Murray–Darling basin]] [[Category:Dams in Victoria (state)]] [[Category:Former dams]] [[Category:Goulburn Broken catchment]] [[Category:Reservoirs in Victoria (state)]] [[Category:Rivers of Hume (region)]] [[Category:Wetlands of Victoria (state)]] [[Category:Rural City of Benalla]]