A Eurobodalla council report says the Tomakin sewage plant repeatedly exceeded its EPA phosphorus limits in 2025-26. Councillors voted 8 to 0 to move its upgrade, estimated at $62 million, to the next phase

If your toilet flushes to the Tomakin plant, which serves Rosedale, Guerilla Bay, Mogo, Tomakin, Mossy Point and Broulee, the council has put in writing that the plant is not keeping up. The report to Eurobodalla Shire Council's 29 September meeting says a review of effluent monitoring for the 2025-26 reporting period identified repeated exceedances of EPA licence limits for total phosphorus (TP), and that the council is upgrading all of its plants with Tomakin a priority as the worst performing plant (agenda, report IR26/011, page 53). Councillors voted 8 to 0 to move the upgrade to its next phase: finishing the detailed design, preparing tender documents and seeking the approvals it needs (minutes, resolution 26/141). The report gives an estimated project cost of $62 million and no construction date.

What the council's report says

The plant was commissioned in 1985 and can treat about 10,000 EP (equivalent persons), an average dry weather flow of about 2,200 kL a day. The report says holiday occupancy at Christmas and Easter already pushes average dry weather flows towards the plant's practical treatment limits, and that Recent maximum dry flow events have exceeded the nominal plant capacity of 2,200 kL/day on multiple occasions (page 52).

On phosphorus, the report does not leave the cause open. It says the exceedances are consistent with the absence of chemical dosing facilities at Tomakin STP and limited process resilience under variable hydraulic conditions, and that the plant was not designed to meet the current increased EPA licence requirements for nutrient removal and disinfection (page 53). The upgrade's answer is chemical dosing for phosphorus removal and ultraviolet disinfection, plus new odour control at the covered balance tank and a larger solar array.

Tomakin sewage treatment plant, now and after the upgrade

As described in the council's report of 29 September 2026

Now

10,000 EP

About 2,200 kL a day average dry weather flow. Commissioned 1985. No chemical dosing. A 2016 balance tank partly addressed inlet limits in peak wet weather.

After the upgrade

25,000 EP

Adds 15,000 EP. Chemical dosing for phosphorus removal, UV disinfection, new odour control. Solar from 16.5 kWp to 160 kWp.

What the EPA's register shows

The plant runs under Environment Protection Licence 2851, held by the council. The licence sets two concentration limits for total phosphorus in the treated effluent, measured from monthly composite samples: 8 milligrams per litre at the 90 percentile and 10 milligrams per litre at the 100 percentile. In the licence's own definition, a percentile limit is the percentage of samples over the reporting period that must meet it, so nine in ten samples must be at or under 8, and none may be over 10. The discharge point is a submarine outfall pipe, and the licence identifies an ambient water monitoring point in the bathing waters of Barlings Beach (licence 2851, conditions P1, L3 and M2, licence version dated 22 January 2021).

The licence requires an annual return to the EPA for each reporting period, and the EPA's public register lists the returns with a column headed Non-compliance. For Tomakin, that column reads Yes for each of the five returns covering 1 April 2020 to 31 March 2025, after five years of No before that. Of the 25 returns the register lists as received since the year to March 2001, 13 are marked Yes (EPA public register, licence 2851, read 8 October 2026). The register does not say which conditions those were, so we do not know whether they were phosphorus.

Tomakin's annual returns to the EPA: was non-compliance recorded?

One cell per licence reporting year, 1 April to 31 March

1. 00-01: No
2. 01-02: Yes
3. 02-03: Yes
4. 03-04: Yes
5. 04-05: Yes
6. 05-06: Yes
7. 06-07: No
8. 07-08: Yes
9. 08-09: No
10. 09-10: No
11. 10-11: No
12. 11-12: No
13. 12-13: No
14. 13-14: Yes
15. 14-15: Yes
16. 15-16: No
17. 16-17: No
18. 17-18: No
19. 18-19: No
20. 19-20: No
21. 20-21: Yes
22. 21-22: Yes
23. 22-23: Yes
24. 23-24: Yes
25. 24-25: Yes
26. 25-26: not shown as received

Yes No Not shown as received

The register lists the return for the year to 31 March 2026 as not received. We do not read that as a finding. The register carries a notice that it is moving to a new system and that During this transition some information on our current site will only be accurate as at 28 April 2026. (EPA public register). The licence allows 60 days after the end of each reporting period to lodge, which for the year to 31 March 2026 is 30 May 2026, a month after 28 April (licence 2851, page 5). The council's own report is the newer word on 2025-26.

Why Batemans Bay is part of this

Tomakin is not only about Tomakin. The report says the Batemans Bay and Tomakin plants are operating near or beyond maximum capacity, and that the Batemans Bay plant has little room to grow: Land availability restrictions at Batemans Bay STP mean the options for increasing capacity at that plant are very limited. In wet weather, it says, the Batemans Bay plant diverts untreated wastewater into emergency storage, and that can lead to unauthorised discharges (pages 50 and 51).

So the council's strategy, set in its 2022 Integrated Water Cycle Management Strategy, shares the load across catchments. Diverting the Malua Bay and Lilli Pilli catchments from Batemans Bay to Tomakin is expected to add about 500 kL a day to Tomakin's average dry weather flow, which the existing plant cannot take (page 52). That matters for anyone following the revised Batemans Bay masterplan, which is weighing where more housing should go in the town. The report says the project will restore operational headroom at the Batemans Bay plant, and lists constraints on housing growth among the risks the council faces without the investment (page 51).

The northern Eurobodalla sewerage strategy, in the report's three steps

1. 1Upgrade Tomakin from about 10,000 to 25,000 EP. The report calls it the main enabling project. This is what councillors moved forward on 29 September.
2. 2Divert Malua Bay and Lilli Pilli from the Batemans Bay plant to Tomakin, about 500 kL a day of average dry weather flow, with the works timed to finish with the Tomakin upgrade.
3. 3Batemans Bay Stage 3 clarifier upgrade, optimising that plant's operational capacity by 2040, depending on growth.

The report also puts a housing number on the whole program: it would increase capacity in the region by about 13,300 EP, which at its conversion of 3 EP per household it equates to about 4,428 new homes, enough on the 2022 strategy's projections to cover the northern area out to at least 2050 (page 53). That regional figure is smaller than the 15,000 EP added at Tomakin, and the report does not explain the difference.

What councillors decided, and what comes next

Councillors adopted points 4 and 5 of the staff recommendation word for word and changed the first three. Staff asked council to acknowledge that not proceeding carried rising risks and that doing nothing is not an option. The resolution, moved by Councillors Schutz and Winslade, replaced that with a shorter line, and changed "acknowledges" to "notes" in the first two points. All eight councillors present voted for it; Councillor Mayne was an apology (minutes, resolution 26/141).

Point 3: the staff recommendation and what council resolved

Staff recommendation

That Council acknowledges failure to proceed with augmentation presents increasing strategic, environmental, operational and growth risks to the northern region sewerage network ie doing nothing is not an option.

Resolution 26/141

That Council acknowledges the necessity of this project.

The $62 million is the report's estimated project cost. The same report says NSW Public Works produced an updated project estimate in March 2026, based on recent tenders it received for similar projects in NSW, and that The estimate includes a conservative contingency. The project is to be paid from the council's sewer fund, financed through a mix of cash reserves and loans, and Design work has intermittently progressed on the Tomakin STP Upgrade project since 2018; it is about 75 per cent complete (page 54).

Three approvals sit ahead, per the report's table: the council's own determination of a review of environmental factors under the planning act, an approval to augment sewerage services under section 60 of the Local Government Act from the agency the table lists as Lands and Water, and a variation of licence 2851 by the EPA (page 52). Then a further report comes back to council after design and tender, with updated project costs and a recommendation on the construction contract. The business case went to councillors as a separate attachment, which we have not read.

Our view

This is opinion, built on the documents above. The 8 to 0 vote was the right call, and if anything it is late. By the council's own account the plant was not designed for its licence's current nutrient requirements and has no chemical dosing, which the report links to the phosphorus exceedances; design has moved intermittently since 2018; and the EPA's register marks non-compliance on each of the plant's last five annual returns it lists as received. A plant the council itself calls its worst performer should not wait for the next growth spurt to be fixed.

Two things should come with the next report, not after it. First, the numbers: the report says the exceedances were repeated but not how many or by how much, and residents of Broulee and Mossy Point are entitled to see the 2025-26 phosphorus results against the 8 and 10 milligram limits. Second, the bill: the report says the sewer fund will borrow, but not what the loans would mean for sewer charges. Ratepayers should know that before councillors sign a construction contract, not after.