SLWLC PublicMeeting#3:Erosion,TagishCommunityCentre,
7November2013 (stated measurements, estimated only)
Attendees: Rob and Mary Ann Lewis, Mark Wedge, Jean Kapala, Deb Fulmer, Dorothy Gibbon, Paul Prevost, Gerry Peters, Susan Gwynne-Timothy, Ed Lishman, Sue Greetham, Mike Miles (Guest facilitator)
67 attendees, including 58 from the communities of concern.
OpeningRemarks: SueGreethamthankedthemanypeopleattending,andadvisedthemtoasktheirquestionstoMikeMiles. Resume attached to minutes.Suerequestedpeoplespeakbriefly,max1 to 1.5minutes,statingfactsasrelatetotheirownproperty.SuealsothankedYECfortheirsupport,funding,accesstodocumentation,andforallowingSLWLCtoacquire the ‘best available’ professional support to the issues.
Prayer: MarkWedge
Erosion Presentation: Introduced by Sue Greetham
Mike Miles gaveapresentationontheSouthernLakes Enhanced Storage Project based on documents made available by Yukon Energy Corporation, imagery or notes provided by local residents and a compilation of historical air photos for representative locations. YEC concept data gathered over the past 3 years was reviewed, relevant data to the topic was interpreted and summarized in a Power Point presentation. A copy of this presentation is included in the Final Report.
MikeMileshasalongassociationwiththeYukondatingback40years. Hehasworkedonvariousprojectsincluding Mayo River for YEC,the YukonSalmonCommittee and DFO. However, hehasnoexperiencewithin the Southern Lakes.Heemphasized the need for communitychampions in assuming a stewardship position on behalf of the community,andcongratulatedtheSLWLC. Mikealsoemphasized thatthis meetingis for the benefit of theresidents,urgingallto engage in the process, submit their testimonials, photos, studies, etc. and provide direction to the committee on the path forward.
Power point Presentation (page and diagram listed throughout)
Thegates on the Lewes Control Structurestayopen betweenMay15 and August15 annually and the project has little or no effect on lake levels in this freshet period. Thecurrentwaterlicenseallows 2.43 m/8 ft. of enhanced water storage in the period between August 16 and May 14. The proposed project would maintain the same schedule, but increase the maximum water level by 0.3 m and reduce the minimum water level by 0.1 m. These elevated periods of high water in the late summer and fall would have the potential to further increase shoreline erosion during the open water period.
Structures to control water level on the Southern Lakes were constructed or reconstructed in 1922, 1950 and 1975. All water level data gathered on the Southern Lakes storage area by the Water Survey of Canada [WSC]hasbeen collectedsince these controls were put in place. As a consequence we do not have baseline data which can be used to determine how the existing project affects natural water level elevations. These data are needed to evaluate the effects of the existing project and to determine the incremental or cumulative effect of the proposed increase in storage capacity. Specifically, the percentage of time various water level elevations are exceeded in each month of the year should be determined for the present conditions using WSC lake level data and calculated for both the natural or baseline and proposed enhanced operating regime using the hydraulic model developed for YEC by Northwest Hydraulic Consultants Ltd. [NHC]. This analysis would allow an estimation of how long water levels would be high enough to cause bank erosion at a particular location under the three scenarios.
Miketoldus thatthekindsofshorelineerosionproblems observed on the Southern Lakesare alsoexperiencedon other northern reservoirs such asAishihikLake or Mayo Lake. Photos were presented illustrating stabilization measures constructed by YEC at the community of Aishihik to prevent accelerated shoreline erosion as a result of wave action during extended periods with high water levels. Other potential effects include bank collapse as a result of melting permafrost and inundated riparian vegetation.
Surficial geology mapping indicates the extensive distribution of finetexturedsoilinthesouthernlakes,whicherodeseasily as evidenced by the photos submitted by our community members.
Mikecompared the seasonal variation in water levels on AtlinLake and MarshLake, based on data collected by the WSC. These data indicate that AtlinLake levels dropquickly in the autumn,whereasMarshLake levels remain comparatively high once the gates in the Lewes Control Structure are closed. Thenatural late-summer and fall waterlevelsonMarshLake would be much lower and this would reduce the potential for shoreline erosion during this open water period.
Mike presented graphs illustrating how the annual maximum and minimum water level elevations have varied on Marsh Lake. This analysis indicates that the proposed full supply level has only been achieved 16 times in 49 years period of record and that the proposed low supply level has only been reached 3 times. YEC needs to provide additional analyses to describe how the frequency and duration of proposed changes in lake elevation will be affected by the proposed project. The annual minimum water level data from Bennett Lake suggests that there was a trend of decreasing levels between 1949 and 1956. This suggests that climate change, dredging or other external factors can influence lake levels. YEC will therefore also need to consider how these types of processes could affect lake levels.
YEC’s consultant AECOM have surveyed representative beach profiles and calculated if the elevations of wind-driven waves would intersect potentially erodible sections of shoreline. These analyses are based on predicted wind velocities for return periods of 2, 5 and 10 years, based on data from Whitehorse.
The significant wave height calculations are the average of the largest 33% of the predicted waves and individual waves will significantly exceed this value. The lack of local wind data is a significant concern, as is the limited number of representative cross sections.
The results of the wave height calculations and analysis of shoreline changes as indicated by historical air photos were reviewed for representative sites.
Mike Miles requested that community members contribute to this discussion.
NorthMcClintock/ArmyBeach:
Question:LloydAtkinson(LA), McClintock Contracting has performed muchoftheerosioncontrolatArmyBeach. The watercomesinearliernowthanitdid20yearsagotolowlevelareas such as thedayusearea.However,waterdoesnotgetto the current highbanks due to extensive prior erosion.Somebank still exists furtherdownArmyBeach.ArmyBeachhasseveraldifferentheights. The chart shown shows only 1elevationand thus one 1behaviour whereas, we know the situation varies from locate to location.
Mike Miles response: The bank cross-section surveyed in 2011 was selected by AECOM as a representative location. Other sites could have different bank elevations or profiles.
McClintockBay(page 19)
Mike Miles illustrated how soil bio-engineering using willow cuttings has been undertaken to help stabilize this eroding bank.
Mike Mikes discussed potential wave effects.(diagram,bottom of page 19, “PrePostproposed concept LakeLevelstogetherwiththeSignificantRun-upElevationforOctober”) Waves presentlyhitjustbelow the banknow.Waveswillhit the bankat an elevated and steeperpointwhen lake levels are raised in the fall. Extremewaveswould alsobehigherthanthevaluesdepictedon this graph
Question Deb Fulmer: Does this graph include storm surge?
Mike Miles response:No, changes in lakelevel elevations as a result of prolonged wind are not considered.
Mike Miles reference: (chart, top of page 20: “Run-upElevationsfor2,5, 10 year storm ReturnPeriod). A2yearstormhas50%chanceofoccurring in any one year, a5year return period event has a 20%chance and a 10 yearstormhas10%chanceofoccurringeveryyear. The analyses assume thewindisfrom the south;blueshadedboxes on the summary table indicate that the predicted wave heights dointercept erodible sections ofbank,whiteboxesdon’t.
Doug Phillips, S.McClintock: there are differentwinds today than in the past,i.e. we get wind from the westmoreoften than in the past.
Mike Mike’s response: AECOM analyses have used Whitehorsewinddata. LOCALwinddata is however needed as MarshLake or Bennett Lakewindscould bedifferentfromWhitehorse. It would be useful if local residents could install staffgauges (like a yard stick, but with large numbers) and measure water levels atdifferentlocations. Photographs, or ideally videos, could be taken to measure wave heights
NewConstabulary:
Comment Lloyd Atkinson:trees have died and fallendown;banknowgoesstraightdownwherethere was an extended sloped beach previously.
QuestionPerrySavoie:Sedimentationcaused by increasederosiondueto current reservoirlakelevel.HowmuchofthatextraerosionsettlesoutintothereservoirthatisMarshLake?Dowejustalreadyexacerbatetheerosionbyholdingthewaterhigher?Beforethedamwehad “MarshLakeFlats”. Sedimentationnowpresentingtotallydifferentlyforturningturbines. This changes the wholeperspectiveof the countrysideadjacentto the water. Ihadsimilarexperience to this whenlivingbyCowichanRiver.Thelast50yearsofsedimentation there arenowcreatingabigproblemthatwasn’ttherebefore.
Mike Miles response: There is a large fine textured sediment plume in the lake adjacent to New Constabulary on both the 1948 and 2013 aerial images. However, additional analyses would be needed to determine how the increased late-summer and fall lake levels have affected sediment production.
Perry Savoie:Yesbutthereisadrasticdifferenceonthebank,sowheredidthatsedimentgo?
Mike Miles response: The finest sediment could potentially be carrieddownstreamand might be found in L. Laberge;coarsersedimentwouldbefound closer to shore. It is possible to datesediment deposits bylookingat the annual layersina collected core. Post-Chernobyl sediments can be identified on the basis of Cesium-137 concentrations.
TagishLake:3siteswherehavedatap22topdiagram
[note: Tagish residents who asked specific questions included Ron Tait and Art Johns. If online readers of the minutes know who asked a particular question, please let Committee know so we can revise the minutes].
______: My question is about Groundwater levels since2007.Iliveat thebeachanditusedtobedryin the springtime. Nowinspring, the groundissowetaloaderwouldsink.I’llbesunkif the supply level rises and remains high longer.
Art Johns:Myfatherboughtourpropertyin1937.
______:Since2007mygroundissupersaturated. Waterisnotgoingbacktothelake. It seems thewaterishigherthanit’severbeen.
Mike Miles response: It would be useful to measure lake andgroundwaterlevelswith arecorderand determine how one affects the other.
YEC Travis Ritchie: The waterlevel is not duetoour control structureso we canonlyspeculate. This can be measured, people can buy a gauge;$500.00 is the price of a reasonablegauge.
SLWLC Sue Greetham:Groundwater will be a primary topic for a future Public meeting.
YEC Travis Ritchie: Suggestions were made for private mitigation measures such as i) subsurfaceimprovementssuch as sump pumps ii) build-up of septic beds.
______:Hasanyonesupportedyour FSL concept?
YEC Travis Ritchie: We have had a mixofreactionsfrom the public.Some have unaffected property, some withhold comments until they hearmorewhileothersaffectedsayno.
______:TagishBeach:Ifprojectgoesahead, we surehopeforsomemitigation from YEC.2012visit,lotsoferosion, thiskindoferosiondoesnotoccuratcurrenthighlevelbutatthe+30cmproposedlevelitwould,soIamveryconcerned.
Mike Miles reference: (Topdiagrampage24:Tagish/TakuSubdivision -NorthRun-upElevationsToeofBank) Notethatallboxesfor2,5and10 yearreturnperiodsareblueand projected wave heights all hit the bank. (Diagramtopp 25CaliforniaBeach). The predicted 10 yearreturnperiod wave height is 1.08m/3ft 6.3 inches which indicates the exposed position and large fetch at this site.
______: The water level andwind has increased at Tagish over the last20years.
Mike Miles reference: (page 27Carcross)Banksaremediumcoarsesand,therefore, erosion prone.
EL: Quiteabit of change.
______CTFN:Witnessed a lotmorewestwind and greatergroundsaturationsince2007.Whenthe damwentin,beaches disappeared,andnowit’sgoodtoseebeachesbutittookyearsfor the beachestocomeback.
Mike Miles response:Elderscanprovide very useful observations.
______:AnyconsiderationofMuskratandfishpopulations? Some populations only breed at certain waterlevels.
SLWLC Sue Greetham: Fish & Wildlife will be a primary topic for a future Public meeting and you can post questions on the web site. Answers will follow on the site. We can have more questions on alternate topics with time available.
Mike Miles: Travis Ritchie of YEC is a biologistandthereare numerous biologicalreportson the YECwebsite. Travis Ritchie would likely be happy to answer your questions after this meeting.
Mike Miles reference: (page28topdiagram)Windandwave heights need to be measured at representative sites to validate AECOM’s wave height analyses.
It will be challenging to predict the incremental effect of raising and further prolonging high water levels in the late-summer and fall. An initial basis for making this assessment is to determine how the existing project has affected the location, rate and volume of bank erosion. This will require data on how the frequency and duration of water levels have changed on at least a monthly basis. Historical air photos, property surveys, ground photos, etc., should be used to establish the location and rate of shoreline retreat. The data can be used to help calibrate wave height and shoreline erosion models once reliable wind data is available.
BruceBeaton: The rocked lined shorelineonmyproperty was installed by the previousowner,but the 2007floodincreasedwaterlevel and we had to request morerocks.We were also informed that we needed toget a $150.00shorelinelease to install the rocks and we stillgetbillseveryyeartopayforthiseventhoughitisYTGshoreline.
Perry Savoie: The ruleonthatjustchanged. You canget a 10yearlease and now there is no charge for the application.
MarkWedge:Howmuchworsewillitgetif YEC holdthewater even higher?Also,if YEC scrapthisconcept,whatcanbedoneaboutcurrenterosionproblem?
Mike Miles reference:Technology exists to stabilizeshortsectionsofbeach (such as at Aishihik)butit’s costly.
______:Whywouldn’t YukonEnergycoverthat?
(Page 30Diagram)Review Effectiveness ofEmployedBankStabilizationTechniques:
Mike Mile reference: Gabionsarewirebasketsfilled with rocks and can be used as an alternative to rip-rap as a means of stabilizing eroding banks.
(Page 30botdiagram) Soil Bio-engineering can expedite the establishment of vegetation and roots and is another possible method of stabilizing eroding sections of shoreline.
Deb:Our problemis that the wateris toohigh in the fall anditdrowns the willow shoots.
Richard Mueller: Ihavehadsome waterfront propertyfor~30 years. Ihavesignificanterosionproblemsnow;evenmysurveypinsarenow impacted.My planned erosioncontrolisforcurrentlevelsandifwater is raised and held tonewfullsupplylevel,Iwillhavetoredesign a wholenewerosioncontrolsystem and I would continue to liveinaconstantconstructionzone at risk.
Mike Miles response: I understand your concern.
(Page 31Diagram) It would be useful to run trialsof bank stabilization techniquestodetermine the costandeffectiveness of techniques to stabilize eroding sections of shoreline. More specifically, the community and YEC needs to determine which techniques best suit particular locations and what is the estimated per meter cost for installation and maintenance? It is also necessary to determine what locations and distance requires mitigation. YEC has prepared a map showing the areas that they have identified as sensitive to high water impact. Is the map accurate, complete and are you located within these areas?
(P33TopDiagram)Identifyotherimpactsbeyondanthropocentric/humans relatedtoincreasedhigh water levels and shoreline instability.
KevinBarr:Onethingnotdiscussedtonightis the collectivepropertytowhichdamhascausedproblems and further worsenedbynaturalerosion.Roadshavesuffered like ReidRoad atendofCaliforniaBeach.Emergencyvehiclesandschoolbusescannolongerturnaround as a result of the shoreline and embankment loss.Whatwillitcosttaxpayerstorepair just this road?Aswell,beaverandswansarehavingtheirhousesaffectedbyerosion,justasweare and that’s out fault.
Richard: The high banks on the Westsideoflake are slidingdown and the commonsecology is being affected.
Deb:Sedimentthisyear has extendedfromArmyBeach Point toM’Clintock Bay.
______:Lowering the water level by -10cm/4 inches through the proposed concept willcauselowericeandlessopenwaterinspring.Lastyearwith a colderspring,7swansdied that we know of.
TYEC Travis Ritchie: that??______Infoandanalysishasbeencompleted.
AnnMidler:6MileRiverisahabitatprotectionareaanditisslumpingintothewater,causingfearsthattherewillbelessareaforswanstofeed.Ecologicaleffectsofthisprojectaregroundwater,swansandfisheries.
Deb Fulmer: SLWLC has approachedorganizationsandconsultantswhohaveagreedtoanswerthesetypesofquestions.
Mike Miles: The sedimentstudies I have reviewed have not specifically addressed salmonand wildlife-related impacts.
(Page 33Bottomdiagram) I would recommend that the costs to mitigate current loss and potential future loss due to shoreline erosion be determined as a basis for evaluating whether the proposed project is economically feasible.
(Page 34) Negotiate with YEC!
Mike Miles:Peopleherehaveconsiderableinfluence,especiallywiththe press.
Doyouwanttohave the proposedconcept?
Will acceptance provideawindowofopportunity to address the existing erosionissues?
Doyou require thatcurrent problem areas be stabilized?
______CTFN 6 Mile River has valued shoreline culturally significant sites, as well as other sites on the Southern Lakes System. How could those be mitigated and protected?
YEC Travis Ritchie: Work has been undertaken and is ongoing confidentially with CTFN and the archaeologists but if our proposal proceeds, YEC will definitely have to address these issues in more detail.
GaryPettifor:BeforeArmyBeachwascreatedbysilt;itusedtobe called MudBay.The waterfront access roadusedto by located on the waterfront side of the cottages,nowitgoesin front/North side ofthe original and newly built homes, as Army Beach Road.Ihavespent$XXXX.00 todateonerosionprotection for my propertyandfeel I should be compensated by Yukon Energy due to the continued high water levels and continued damage.
DebFulmer Presentation: M’Clintock Bay
On the MarnyRyder,RebaMiller properties including testimonials+bioengineeringworkdone.
Marny Ryder has lived at South McClintock since 1952 and has completed a report based on records she and her husband kept as a result of rising property taxes and the loss of property through erosion. They have lost 65 ft. of shoreline property due to multiple reasons ~ higher glacier run-off, more boats, Lewes Dam, increased wave action. They are having trouble keeping up with repairs that seem beyond their control.
(Diagram) Ryder property at corner, various photos 1950s, 1960s show decreased property, loss of lower bank shown in 1978 photo. 2008 Water level not bad in terms of maximum height yet shoreline trees were flooding.
Fulmer property lost 2m/6.6 ft. in the 2007 flood. As a result 4 neighbours got together and performed a trial bio-engineering mitigation effort. At proposed full supply level, 2009 and 2012, part of the bio-engineering planting collapsed due to water height/waves. The project did work to a degree in protecting the bank. This year, did have higher water than 2012 and further damage. Vegetation is establishing at bank bottom, despite having only 10-20% vegetation still alive.
Mike Miles: Does the ice affect the vegetation?
Deb Fulmer: No, the ice just stays on the bank.
Deb Fulmer: (Diagram showing cribbing at bank base & vegetation) The Lois Craig property shows water rising above the crib in 2013. The bank has further eroded and in-filled with sediment behind the crib. The top of the bank has been stable since 2007.
Reba Miller’s house is physically threatened by critical and fast moving erosion of her shoreline. Reba has natural vegetation established.
YEC TravisRitchie:Deb’smitigationisworkingand the 2012/2013 natural high-water level is 20cmhigherthan the proposed fullsupplylevel. This is not considering the duration of the high water as proposed in the YEC Concept through the fall and winter.
Deb Fulmer:itwasonestormathighwaterthatcausesthedamage.
YEC Travis Ritchie:Naturalis 20.3cm/8in. higherthanprojectfullsupply.
Deb Fulmer: Our bioengineeringproject is ongoing. Wehavehiredstudents and put inalotofhoursonthis mitigation work/
Gary Pettifor:Areyoulookingto the government todosomething?
Deb Fulmer:We willapproachYTGfor fundingforexistingdamageandwecan also dothatasagroup in a formal partnership application or individually.Asagroup,weneedto define whatwewantand present it. With strength and continuity in numbers, we may see some success much sooner.