The 22-year-old defender leaves the Trotters without making a senior appearance since joining from Leicester City 18 months ago.
Bolger re-joins Southend for a reported £25,000 fee after a brief spell on loan with the Shrimpers last season.
He made one appearance for the League Two side before getting injured and missing the rest of his loan stint.
Restore Data
| Team | P | W | D | L | F | A | GD | PTS | |
| 1 | York City | 17 | 11 | 5 | 1 | 33 | 12 | 21 | 38 |
| 2 | Forest Green RoversForest Green | 17 | 11 | 4 | 2 | 33 | 14 | 19 | 37 |
| 3 | Barnet | 17 | 11 | 1 | 5 | 34 | 20 | 14 | 34 |
| 4 | Gateshead | 17 | 10 | 3 | 4 | 28 | 22 | 6 | 33 |
| 5 | Oldham AthleticOldham | 17 | 8 | 7 | 2 | 25 | 17 | 8 | 31 |
| 6 | Rochdale | 17 | 9 | 3 | 5 | 27 | 16 | 11 | 30 |
| 7 | Yeovil TownYeovil | 17 | 8 | 4 | 5 | 21 | 15 | 6 | 28 |
| 8 | Halifax TownHalifax | 17 | 7 | 5 | 5 | 19 | 16 | 3 | 26 |
| 9 | Solihull MoorsSolihull | 17 | 7 | 4 | 6 | 26 | 28 | -2 | 25 |
| 10 | AltrinchamAltrincham | 17 | 6 | 6 | 5 | 26 | 23 | 3 | 24 |
| 11 | Eastleigh | 17 | 6 | 5 | 6 | 25 | 25 | 0 | 23 |
| 12 | Dagenham & RedbridgeDag & Red | 17 | 5 | 7 | 5 | 27 | 18 | 9 | 22 |
| 13 | Sutton UnitedSutton | 17 | 6 | 4 | 7 | 25 | 26 | -1 | 22 |
| 14 | Tamworth | 17 | 6 | 4 | 7 | 20 | 28 | -8 | 22 |
| 15 | Southend UnitedSouthend | 17 | 5 | 6 | 6 | 20 | 20 | 0 | 21 |
| 16 | Hartlepool UnitedHartlepool | 17 | 5 | 6 | 6 | 18 | 21 | -3 | 21 |
| 17 | Aldershot TownAldershot | 17 | 4 | 6 | 7 | 21 | 27 | -6 | 18 |
| 18 | Fylde | 17 | 5 | 3 | 9 | 23 | 36 | -13 | 18 |
| 19 | Woking | 17 | 4 | 5 | 8 | 18 | 24 | -6 | 17 |
| 20 | Braintree TownBraintree | 17 | 4 | 4 | 9 | 13 | 20 | -7 | 16 |
| 21 | Maidenhead UnitedMaidenhead | 17 | 4 | 4 | 9 | 21 | 30 | -9 | 16 |
| 22 | WealdstoneWealdstone | 17 | 3 | 6 | 8 | 16 | 25 | -9 | 15 |
| 23 | Boston UnitedBoston | 17 | 2 | 5 | 10 | 16 | 30 | -14 | 11 |
| 24 | Ebbsfleet | 17 | 1 | 5 | 11 | 15 | 37 | -22 | 8 |
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