What’supwithourlakes?JohnA.Downing

LifetimeSeasonalResidentofWabana COLMinnesotaSeaGrantProgram

Duluth&St.Paul

Sometopics

•Geology– whyourCOLexists•Oxygendemand- Whatwe’reseeingandwhatitmeans

•Algaeblooms-• Invasivespecies•Humanissues

Glaciersformedourlandscape

Whyourchainoflakesexists

Tall,graveleskerattheSWofTroutLake

ViewoftheeskeronBluewater

FlowtotheCOLfromtheeskergroundwatersystem• ViaTroutLakechannels:

• 1/4m/second(4mwidex0.5mdeep)• 1m3/sec• 100,000gallons/hour

• ViaBluewaterchannel• 0.15m3/sec(3mwidex0.5mdeep)• 15,000gallons/hour

• Closetothisyear-round– notmuchinfluencedbyrainfallandrunoff• What’sinthegroundwatermatters

Basic limnology: summer stratification

Deepwateroxygen– whyitmatters

• Troutandciscos need4mg/Ltoliveandreproduce• Alsoneedtobebelow52degreesF(11degreesC)• Andtheyreproduceinfall

• Otherfishcan’tlivebelow2mg/L• Oxygeninspringisaround12mg/L

Whatusesdissolvedoxygen?

• Startshighinspringbecauselakemixestoptobottomandtakesinoxygenfromtheair

• Normally,oxygenistakenoutofthewaterbydecompositionofstuffgrowinginthelake

• Algae,fueledbynutrientistheusualthingthatdecomposes• Chemicalprocessescanaddtoit• Eutrophicationfromhumannutrientsmakesitincreaseveryfast

• OxygendepletioninthedeepwateroftheCOLis5-10timesfasterthanweexpectforaclearwaterlake

9sitessincemid-May

Oxygenconditionsnow

• ManyplacesintheCOL,nofishcansurvivebelow30-40feet• DeepwaterinsouthTroutlowerinoxygenthannorthTrout• Fishinasandwichbetweenwarmwaterandlowoxygen– andit’sgettingworse(need>4mg/Loxygenand<52degreesF

• DeepwaterinnorthBluewaterlowerinoxygenthaninsouthBluewater

• Interlochen(aka“LittleTrout”)hasnooxygenbelowabout35feet–nevermixes

• We’retryingtofigureoutthesourceofphenomenonfortheseandother“CiscoLakes”soitcanbefixed

• Seemsasifgroundwaterisinvolved

Hasthischanged?

• Ratesofoxygen“demand”5-10xtheamountseeninotherclear-wter lakes• SurveysIdid15yearsagoshowedsomelowoxygenbutnotasmuch• Roleofclimateandnewnutrients?• MyancestorscaughttroutinWabana• Iusedtofinddeadciscoesontheshore• The“ciscolakeproblem”isoneofthebigmysteriesDNRistryingtosolve

(Springoxygen)-(naturaldemand)-(demandduetonewnutrients)-(chemicaldemand)=(Augustoxygen)

Algaeblooms–why?

Thisyear’sspringbloom

• Ourspringbloomwasabluegreen algaespecies• Wabana warmedfromicetoswimmablein3weeksbeforeMemorialDay

• Whenlakesmixinspring,nutrientsfromthedeepwaterareavailabletoalgae

• I’mseeingmorealgaeinthewaternowthanI’veseeninthepast• We’veseenalotofglobsoffilamentousalgaewehaven’tseeninthepast

• Climateandincreasednutrientsthelikelycauseofincreasedalgae

Whyshouldwecareaboutthis

• Somespeciescanbetoxictopeople,pets,andaquaticlife• Theycanstinkandaddodorandflavor• Theyareasignofdecliningwaterquality

Invasivespecies

Howdotheygethere

• Mostlybyaccidentaltransportbyboatsvialandings• 3officialboatlandingsonthechainoflakes• Watercraftinspectionsarehelpful• Boatsarriveoutofinspectionhoursandatunofficiallandings,too• Nearbylakeshaveavarietyofspecies

• Zebraandquaggamussels• Didymo• Spinywaterflea• Starrystonewort

• “Cures”notinnear-futureso“prevention”iskey

Lot’sofwaystoincreasesafetyfromAIS

Boat-inCampsites

Concernaboutsanitaryconditions

GrowingnumberofcampsitesontheChain

Concernsaboutboat-incampsites

• Untreatedwaste• Nutrients(50peopleforadayproducesewageof1personfor2months)• 50%ofphosphorusoutputisasurine• Disease-causingmicrobes(bacteria,viruses,otherpathogens)

• Bigpartiesanddrunkenboating• Firehazards• Litter• “commonproperty”resourceproblem- whenitbelongstoeveryone,wholooksafterit?

GrowingnumberofcampsitesontheChain

Navigationisgettingcomplicated

Safetyofpeopleandtheresourceisimportant• Right-of-wayrulesseemunknowntoboaters

• Motorizedyieldtounmotorized• Upstreamtrafficyieldstodownstream• Morecollisionsinchannelsanddestructivenavigation

• IsthisaroleforWCOLA?

Wildfireprotection&waterquality

• Clearing100’diametercircleis7854sq feet

• 1/5acreperhouse• Cleartotheshoreandnearlytheentirewidthofa250’lot

• Perhapssafeforhousesbutnotforthewater

WhatistheroleforWCOLAin….

• Insuringgoodwaterqualityandhealthyfisheries• Protectingthegroundwaterresourcethatsustainsour“chain”• Algaebloommonitoringandprotection• Aquaticinvasivespecies• Safeuseofcampsites• Safenavigation