| Castle Eden Dene National Nature Reserve | 228.46 ha | | — |
| Chapman's Well Local Nature Reserve | 149.57 ha | | — |
| Blackhall Grasslands Local Nature Reserve | 90.66 ha | | — |
| The Heaps Country Park | 75.75 ha | | — |
| Low Burnhall Woodland Trust | 65.99 ha | | — |
| Auckland Park | 64.06 ha | | — |
| Durham Coast National Nature Reserve | 63.67 ha | | — |
| Daisy Hill Local Nature Reserve | 53.12 ha | | — |
| Crowtrees Local Nature Reserve | 48.25 ha | | — |
| Low Barns Nature Reserve Durham Wildlife Trust | 41.95 ha | | — |
| Gore Burn Local Nature Reserve | 41.12 ha | | — |
| Cong Burn Local Nature Reserve | 40.11 ha | | — |
| Hardwick Park | 39.93 ha | | — |
| Harvey Wood Woodland Trust | 32.18 ha | | — |
| Sacriston Wood Local Nature Reserve | 31.33 ha | | — |
| Horden Grasslands Local Nature Reserve | 30.83 ha | | — |
| Tanfield Lea Marsh Local Nature Reserve Durham County Council | 28.15 ha | | — |
| South Stanley Woods Local Nature Reserve | 27.61 ha | | — |
| Easington Local Nature Reserve | 27.0 ha | | — |
| Nose's Point Local Nature Reserve | 26.74 ha | | — |
| Wingate Quarry Local Nature Reserve | 26.74 ha | | — |
| Ferryhill Carrs Local Nature Reserve | 24.17 ha | | — |
| Kingswood Nature Reserve | 22.37 ha | | — |
| Thrislington Plantation National Nature Reserve | 21.82 ha | | — |
| Baal Hill Wood Durham Wildlife Trust | 20.53 ha | | — |
| Pow Hill Country Park | 18.66 ha | | — |
| Allensford Wood Local Nature Reserve | 17.78 ha | | — |
| Steely Hill Local Nature Reserve | 17.64 ha | | — |
| Raisby Hill Grassland nature reserve | 16.23 ha | | — |
| Greencroft Heath Local Nature Reserve | 15.86 ha | | — |
| Aykley Woods Local Nature Reserve | 15.75 ha | | — |
| Pelaw Woods Local Nature Reserve | 15.68 ha | | — |
| Bracken Hill Wood Local Nature Reserve Durham County Council | 14.8 ha | | — |
| Deep Dene Local Nature Reserve | 14.63 ha | | — |
| Burnhope Pond Durham Wildlife Trust | 14.11 ha | | — |
| Riverside Park | 13.75 ha | | — |
| Harperley and Pea Woods Local Nature Reserve | 13.14 ha | | — |
| Kyo Bogs Local Nature Reserve | 12.52 ha | | — |
| Raisby Way Railway Path and Trimdon Grange Quarry Local Nature Reserve | 12.45 ha | | — |
| Cow Plantation Local Nature Reserve Spennymoor Town Council | 12.28 ha | | — |
| Hedleyhill Colliery Woods Local Nature Reserve | 12.22 ha | | — |
| Low Newton Junction Local Nature Reserve Durham County Council | 11.87 ha | | — |
| Black Plantation Durham Wildlife Trust | 11.68 ha | | — |
| Whitworth Hall Country Park | 11.53 ha | | — |
| Littlewood Nature Reserve | 11.52 ha | | — |
| Woodham Way | 11.37 ha | | — |
| Durham University Botanic Garden | 10.7 ha | | — |
| Byerley Local Nature Reserve | 10.46 ha | | — |
| Pity Me Carrs Local Nature Reserve | 9.71 ha | | — |
| Coxhoe Hall Woods Local Nature Reserve | 9.23 ha | | — |
| Bishop Middleham Quarry Nature Reserve Durham Wildlife Trust | 8.97 ha | | — |
| Newfield Millennium Green | 8.93 ha | | — |
| Hannah's Meadow nature reserve Durham Wildlife Trust | 8.9 ha | | — |
| Genesis Way Park | 8.72 ha | | — |
| Blackhill & Consett Park | 8.51 ha | | — |
| Seaham Town Park Seaham Town Council | 8.48 ha | | — |
| Flass Vale Local Nature Reserve | 8.44 ha | | — |
| Malvern Field | 8.4 ha | | — |
| The Recreation Ground | 8.04 ha | | — |
| Coxhoe Quarry Wood Local Nature Reserve | 7.83 ha | | — |
| The Bowes Museum The Bowes Museum | 7.66 ha | | — |
| Meadowfield | 7.42 ha | | — |
| Jubilee Park | 7.35 ha | | — |
| Cassop National Nature Reserve Natural England | 6.88 ha | | — |
| Hayberries Nature Reserve | 6.57 ha | | — |
| Wood House Park | 6.2 ha | | — |
| Malton Nature Reserve Durham Wildlife Trust | 6.01 ha | | — |
| Fulforth Jubilee Park | 5.91 ha | | — |
| Egglesburn Wood | 5.89 ha | | — |
| Limekiln Gill Local Nature Reserve | 5.87 ha | | — |
| South Hetton Welfare Park | 5.42 ha | | — |
| Dean Bank Recreational Park | 5.39 ha | | — |
| Wharton Park | 5.21 ha | | — |
| Dawdon Park Seaham Town Council | 5.07 ha | | — |
| Annfield Plain Park Durham County Council | 5.06 ha | | — |
| Welfare Park | 5.03 ha | | — |
| Allensford Park | 4.7 ha | | — |
| Coxhoe Park Durham County Council | 4.36 ha | | — |
| Holliday Park | 4.36 ha | | — |
| Willington North Dene Local Reserve | 4.08 ha | | — |
| Jubilee Park | 3.95 ha | | — |
| The Ponderosa | 3.95 ha | | — |
| Ragpath Heath nature reserve Durham Wildlife Trust | 3.92 ha | | — |
| Deneside Park Seaham Town Council | 3.69 ha | | — |
| Glenholme Park | 3.65 ha | | — |
| The Moor Local Nature Reserve | 3.56 ha | | — |
| Woodham Park | 3.36 ha | | — |
| Rockhouse Dene Local Nature Reserve | 3.34 ha | | — |
| Black Plantation Durham Wildlife Trust | 3.32 ha | | — |
| Oakey's Park | 3.3 ha | | — |
| Bowburn Park | 3.07 ha | | — |
| Barnard Castle Grounds English Heritage | 2.93 ha | | — |
| Tow Law Millennium Green | 2.9 ha | | — |
| Sherburn Village Park | 2.69 ha | | — |
| Littlewood Local Nature Reserve | 2.68 ha | | — |
| Addison Park | 2.3 ha | | — |
| North Leigh Play Area | 2.18 ha | | — |
| Thorpe Light Railway | 2.16 ha | | — |
| Winston Millennium Green | 2.16 ha | | — |
| Shildon Millennium Green | 2.12 ha | | — |
| Parkside Neighbourhood Park Seaham Town Council | 2.08 ha | | — |
| Memorial Park | 2.04 ha | | — |
| St Oswald's Park Local council | 2.04 ha | | — |
| High Wood Durham Wildlife Trust | 2.03 ha | | — |
| Waldridge Millennium Green | 1.86 ha | | — |
| Fawcett Park | 1.7 ha | | — |
| Walled Garden | 1.7 ha | | — |
| Rope Moor Plantation | 1.66 ha | | — |
| Canterbury Road Park | 1.62 ha | | — |
| Riverside Gardens | 1.58 ha | | — |
| Gainford Millennium Green | 1.51 ha | | — |
| Great Lumley Millennium Green | 1.35 ha | | — |
| View Lane Park | 1.31 ha | | — |
| Trimdon Millennium Green | 1.29 ha | | — |
| Ushaw Gardens | 1.21 ha | | — |
| Derwentside Park | 1.16 ha | | — |
| Eggleston Hall Gardens | 1.09 ha | | — |
| Old Durham Gardens | 0.95 ha | | — |
| Longburnford Quarry nature reserve Durham Wildlife Trust | 0.87 ha | | — |
| Ushaw Moor Community Garden Ushaw Moor Action Group | 0.14 ha | | — |
| Territorial Lane Garden Durham University | 0.08 ha | | — |
| Friends of Wharton Park | 0.03 ha | | — |
| Burnhill Nature Reserve | — | | — |
| Lintzgarth Fell Nature Reserve Philip Wayre Upland Trust | — | | — |
| Tudhoe Mill Nature Reserve Durham Wildlife Trust | — | | — |