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| IRS990/AccountsPayableAccrExpnssGrp/EOYAmt | 0 | 199338 |
| IRS990/ActivitiesConductedPrtshpInd | 0 | 0 |
| IRS990/ActivityOrMissionDesc | 0 | TO IMPROVE AND MAINTAIN THE EMERALD NECKLACE PARKS FOR ALL. |
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| IRS990/AdvertisingGrp/ProgramServicesAmt | 0 | 12048 |
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| IRS990/ContractorCompensationGrp/ContractorName/BusinessName/BusinessNameLine1Txt | 0 | DANIEL S ADAMS LANDING STUDIO LLC |
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| IRS990/Desc | 0 | OLMSTED TREE SOCIETY - THE OLMSTED TREE SOCIETY WAS FOUNDED IN 2013 TO PROVIDE FINANCIAL SUPPORT FOR THE PRESERVATION AND PROTECTION OF HEALTHY TREES IN THE EMERALD NECKLACE PARKS - CHARLESGATE PARK, BACK BAY FENS, RIVERWAY, OLMSTED PARK, JAMAICA POND, FRANKLIN PARK AND ALONG THE PARKWAYS. THESE EFFORTS ARE MADE THROUGH SELECTIVE PRUNING AND SOIL ENHANCEMENT, AS WELL AS THE PLANTING OF NEW TREES. ALL WORK IS MANAGED BY CONSERVANCY STAFF IN COLLABORATION WITH THE CONSERVANCY'S PUBLIC PARTNERS, BOSTON PARKS & RECREATION, BROOKLINE PARKS AND OPEN SPACE AND THE MASSACHUSETTS DEPARTMENT OF CONSERVATION AND RECREATION. |
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| IRS990/Form990PartVIISectionAGrp/TitleTxt | 3 | CLERK |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 4 | TREASURER |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 5 | DIRECTOR |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 6 | DIRECTOR |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 7 | DIRECTOR |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 8 | DIRECTOR |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 9 | DIRECTOR |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 10 | DIRECTOR |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 11 | DIRECTOR |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 12 | DIRECTOR |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 13 | DIRECTOR |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 14 | DIRECTOR (FORMER) |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 15 | DIRECTOR |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 16 | DIRECTOR |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 17 | DIRECTOR |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 18 | DIRECTOR |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 19 | DIRECTOR |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 20 | DIRECTOR |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 21 | DIRECTOR |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 22 | DIRECTOR |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 23 | DIRECTOR |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 24 | DIRECTOR |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 25 | DIRECTOR |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 26 | DIRECTOR |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 27 | DIRECTOR |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 28 | PRESIDENT |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 29 | DIRECTOR OF DEVELOPMENT |
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| IRS990/FormationYr | 0 | 1997 |
| IRS990/FormerOfcrEmployeesListedInd | 0 | 0 |
| IRS990/FSAuditedBasisGrp/SeparateBasisFinclStmtInd | 0 | X |
| IRS990/FSAuditedInd | 0 | 1 |
| IRS990/FundraisingActivitiesInd | 0 | 1 |
| IRS990/FundraisingAmt | 0 | 39800 |
| IRS990/FundraisingDirectExpensesAmt | 0 | 0 |
| IRS990/FundraisingGrossIncomeAmt | 0 | 0 |
| IRS990/GainOrLossGrp/SecuritiesAmt | 0 | 42029 |
| IRS990/GamingActivitiesInd | 0 | 0 |
| IRS990/GoverningBodyVotingMembersCnt | 0 | 27 |
| IRS990/GovernmentGrantsAmt | 0 | 154000 |
| IRS990/GrantsToIndividualsInd | 0 | 0 |
| IRS990/GrantsToOrganizationsInd | 0 | 0 |
| IRS990/GrantToRelatedPersonInd | 0 | 0 |
| IRS990/GrossAmountSalesAssetsGrp/SecuritiesAmt | 0 | 613122 |
| IRS990/GrossReceiptsAmt | 0 | 2914301 |
| IRS990/GroupReturnForAffiliatesInd | 0 | 0 |
| IRS990/IncludeFIN48FootnoteInd | 0 | 0 |
| IRS990/IndependentAuditFinclStmtInd | 0 | 1 |
| IRS990/IndependentVotingMemberCnt | 0 | 27 |
| IRS990/IndivRcvdGreaterThan100KCnt | 0 | 2 |
| IRS990/IndoorTanningServicesInd | 0 | 0 |
| IRS990/InfoInScheduleOPartIIIInd | 0 | X |
| IRS990/InfoInScheduleOPartIXInd | 0 | X |
| IRS990/InfoInScheduleOPartVIInd | 0 | X |
| IRS990/InformationTechnologyGrp/FundraisingAmt | 0 | 1233 |
| IRS990/InformationTechnologyGrp/ManagementAndGeneralAmt | 0 | 14376 |
| IRS990/InformationTechnologyGrp/ProgramServicesAmt | 0 | 2984 |
| IRS990/InformationTechnologyGrp/TotalAmt | 0 | 18593 |
| IRS990/InsuranceGrp/FundraisingAmt | 0 | 6880 |
| IRS990/InsuranceGrp/ManagementAndGeneralAmt | 0 | 7027 |
| IRS990/InsuranceGrp/ProgramServicesAmt | 0 | 8298 |
| IRS990/InsuranceGrp/TotalAmt | 0 | 22205 |
| IRS990/InvestmentExpenseAmt | 0 | -60447 |
| IRS990/InvestmentIncomeGrp/ExclusionAmt | 0 | 77278 |
| IRS990/InvestmentIncomeGrp/TotalRevenueColumnAmt | 0 | 77278 |
| IRS990/InvestmentInJointVentureInd | 0 | 0 |
| IRS990/InvestmentsPubTradedSecGrp/BOYAmt | 0 | 4876250 |
| IRS990/InvestmentsPubTradedSecGrp/EOYAmt | 0 | 4988327 |
| IRS990/IRPDocumentCnt | 0 | 18 |
| IRS990/IRPDocumentW2GCnt | 0 | 0 |
| IRS990/LandBldgEquipAccumDeprecAmt | 0 | 253472 |
| IRS990/LandBldgEquipBasisNetGrp/BOYAmt | 0 | 708483 |
| IRS990/LandBldgEquipBasisNetGrp/EOYAmt | 0 | 685810 |
| IRS990/LandBldgEquipCostOrOtherBssAmt | 0 | 939282 |
| IRS990/LegalDomicileStateCd | 0 | MA |
| IRS990/LessCostOthBasisSalesExpnssGrp/SecuritiesAmt | 0 | 571093 |
| IRS990/LoanOutstandingInd | 0 | 0 |
| IRS990/LobbyingActivitiesInd | 0 | 1 |
| IRS990/LocalChaptersInd | 0 | 0 |
| IRS990/MaterialDiversionOrMisuseInd | 0 | 0 |
| IRS990/MembersOrStockholdersInd | 0 | 0 |
| IRS990/MethodOfAccountingAccrualInd | 0 | X |
| IRS990/MinutesOfCommitteesInd | 0 | 1 |
| IRS990/MinutesOfGoverningBodyInd | 0 | 1 |
| IRS990/MissionDesc | 0 | TO IMPROVE AND MAINTAIN THE EMERALD NECKLACE PARKS FOR ALL. |
| IRS990/MoreThan5000KToIndividualsInd | 0 | 0 |
| IRS990/MoreThan5000KToOrgInd | 0 | 0 |
| IRS990/NetAssetsOrFundBalancesBOYAmt | 0 | 6249336 |
| IRS990/NetAssetsOrFundBalancesEOYAmt | 0 | 6999167 |
| IRS990/NetGainOrLossInvestmentsGrp/ExclusionAmt | 0 | 42029 |
| IRS990/NetGainOrLossInvestmentsGrp/TotalRevenueColumnAmt | 0 | 42029 |
| IRS990/NetIncmFromFundraisingEvtGrp/TotalRevenueColumnAmt | 0 | 0 |
| IRS990/NetUnrelatedBusTxblIncmAmt | 0 | 0 |
| IRS990/NetUnrlzdGainsLossesInvstAmt | 0 | 515802 |
| IRS990/NoDonorRestrictionNetAssetsGrp/BOYAmt | 0 | 4070835 |
| IRS990/NoDonorRestrictionNetAssetsGrp/EOYAmt | 0 | 4858767 |
| IRS990/NoncashContributionsAmt | 0 | 272195 |
| IRS990/NondeductibleContributionsInd | 0 | 0 |
| IRS990/OccupancyGrp/FundraisingAmt | 0 | 10827 |
| IRS990/OccupancyGrp/ManagementAndGeneralAmt | 0 | 2937 |
| IRS990/OccupancyGrp/ProgramServicesAmt | 0 | 13060 |
| IRS990/OccupancyGrp/TotalAmt | 0 | 26824 |
| IRS990/OfficeExpensesGrp/FundraisingAmt | 0 | 21394 |
| IRS990/OfficeExpensesGrp/ManagementAndGeneralAmt | 0 | 24698 |
| IRS990/OfficeExpensesGrp/ProgramServicesAmt | 0 | 25910 |
| IRS990/OfficeExpensesGrp/TotalAmt | 0 | 72002 |
| IRS990/OfficerMailingAddressInd | 0 | 0 |
| IRS990/OperateHospitalInd | 0 | 0 |
| IRS990/Organization501c3Ind | 0 | X |
| IRS990/OrganizationFollowsFASB117Ind | 0 | X |
| IRS990/OtherChangesInNetAssetsAmt | 0 | 0 |
| IRS990/OtherEmployeeBenefitsGrp/FundraisingAmt | 0 | 37625 |
| IRS990/OtherEmployeeBenefitsGrp/ManagementAndGeneralAmt | 0 | 22398 |
| IRS990/OtherEmployeeBenefitsGrp/ProgramServicesAmt | 0 | 12904 |
| IRS990/OtherEmployeeBenefitsGrp/TotalAmt | 0 | 72927 |
| IRS990/OtherExpensesGrp/Desc | 0 | PROGRAM MATERIALS AND E |