Stage 2: Define objectives and priorities

You now have a picture of your system. The next task is to set clear targets for improvement.

Annex V requires that objectives are explicitly included in every IUWMP (Directive (EU) 2024/3019). Annex V sets an indicative, non-binding objective that storm water overflow should not exceed 2% of the annual collected urban wastewater load, calculated in dry weather conditions. It also requires an estimation of microplastics loads and their consideration in the plan.

The practical challenge: translating the system-level 2% overflow target into something geographically specific: which areas, which pollutants, reduced by how much, and in what order of priority. As a comparable planning framework, the UK Drainage and Wastewater Management Plans (DEFRA et al. 2025) and guidance offer a reference for how measurable objectives can be structured and reviewed, while France's sustainable stormwater action plan illustrates how national frameworks prioritise infiltration and source control (MTECT 2021).

A common mistake at this stage is to jump straight to a single city-wide percentage reduction. That rarely works, because pollution is spatially concentrated. A small share of surfaces can generate most of the load.

A useful test for each objective is whether it meets the SMART criteria: specific, measurable, achievable, relevant, and time-bound (DORAN 1981). The sections below show what this looks like in practice for an IUWMP.

Start by reviewing your Stage 1 pollutant ranking and receiving water risk map. For each priority sub-catchment, ask: what reduction is needed for the receiving water body to meet its quality objectives?

• Grounded in your Stage 1 analysis. If your analysis showed that three road sub-catchments contribute most to your Total Suspended Solids load, your objectives should reflect that concentration of impact. Spreading effort evenly across all surfaces rarely makes sense.
• Quantification. Aim for your objectives to be specific and focus on loads rather than percentages.
• Referenced to water quality standards. EU Environmental Quality Standards for priority substances such as zinc, copper, cadmium and others, define what “acceptable” runoff quality means for discharge to receiving waters (EUROPEAN PARLIAMENT & COUNCIL OF THE EU 2008). Frame your objectives in terms of moving toward those thresholds (EEA 2024; GNECCO et al. 2005).
• Realistic about what measures can deliver. Performance of various measures (bioretention ponds, constructed wetlands, etc.) is concentration-dependent: systems designed for moderate urban runoff reach their physical limits on heavily contaminated surfaces (WOODS BALLARD et al. 2015). For those, source control or engineered pre-treatment comes first. Set targets realistically on what measures can deliver to ensure the credibility of your plan.
• Where to find the numbers. Your national river basin management plan contains the quality objectives for each water body. Cross-reference these with your overflow discharge data from Stage 1. If your discharge monitoring is too coarse, use the estimated pollutant concentrations from your source mapping (Section 1.3) combined with overflow volume estimates. This gives an order-of-magnitude load figure for target-setting, even if it is not precise.

WATERUN Tool 4 Risk-based DSS helps to identify and formulate risk-based targets.

Most cities will face more pollution problems than they can solve in one plan cycle. Prioritisation is therefore a crucial part of objective-setting. Rank areas and pollutants by three criteria:

• the size of the load,
• how connected the source is to a receiving water body,
• the risk it poses when it arrives.

The highest-priority objectives are those where all three factors are high simultaneously. If you are uncertain where to start, a simple scoring matrix can help. Multiply the scores. The sub-catchments with the highest combined scores are your priorities for the first plan cycle.

Table 1. Prioritisation scoring matrix for sub-catchments. Source: OWN ELABORATION (2026)

Look for co-benefits. An objective that reduces copper load from commercial roofs may also make that runoff suitable for rainwater harvesting, turning a pollution control cost into a water resource gain. These combinations may attract different funding streams or broader stakeholder support. The Directive explicitly encourages reuse (Directive (EU) 2024/3019).

WATERUN Tool 4 Risk-based DSS ranks discharge points by environmental and human health risk, supporting the prioritisation work with a quantitative lens.

Before moving on, pause and ask: is the evidence from Stage 1 good enough to support these objectives? If data came from different departments and has never been combined, now is the time to reconcile it. Where your data is weak, either collect more or adjust your objectives to what you can confidently support. (DELETIC et al. 2012; BERTRAND-KRAJEWSKI et al. 2000).

Objectives set in isolation by one department often fail because they do not account for constraints known to another department. If the roads department plans to resurface a major arterial next year, that is an opportunity to integrate permeable paving. If the parks department is redesigning a public square, that is a chance to add bioretention. Coordinating before you finalise objectives presents opportunities for faster approval and cost savings.

Different stakeholders weight different things: environmental impact, public health, flooding, infrastructure condition, cost, etc. Before you select your priority measures, ensure that you take these trade-offs into consideration and structure the conversation around scenarios. Addressing some measures first means delaying others, which is something the key stakeholders need to agree on. Use the priority ranking from Section 2.2 and ask stakeholders to validate or adjust it (STOPUP CONSORTIUM 2025; OFWAT 2013; US EPA 1995, 2022).

Document the agreed priorities and the reasoning behind them, to keep a record and have a clear justification when the plan is reviewed six years later.

Stage 2 Checkpoint. Before moving on, confirm you have:

• measurable objectives for each priority sub-catchment, expressed as load reductions for specific pollutants,
• a ranked priority list validated by stakeholders,
• an honest assessment of data quality behind each objective,
• documented agreement on sequencing and acceptable residual risk

---->  You can directly continue to Stage 3 of the IUWMP Journey or go back to Stage 1 <----

This IUWMP Journey stage is part of seecon's practical interpretation of Annex V of Directive (EU) 2024/3019 within the WATERUN project. It is not official EU guidance. The EU Commission implementing acts on methodologies are due by 2 January 2028 (Art. 5(6)). See the Stage 0 for details on how the four stages were developed.