Wellington Water is preparing integrated stormwater catchment management plans for Wellington City Council. The plans are required by a consent to discharge stormwater issued to the Council by Greater Wellington Regional Council.
Stage 1 of integrated catchment management plan has been signed off by Greater Wellington Regional Council, and we are now moving into stage 2.
What is an ICMP?
An integrated catchment management plan is a plan that takes a holistic approach to managing the inputs and outputs of a stormwater catchment.
Because stormwater travels from roads and roofs to streams, rivers and seas without treatment, contaminants in stormwater contribute to pollution of the receiving environment.
An integrated approach means taking a range of factors into consideration – activity and urban development in the catchment, the state of the stormwater and wastewater networks, levels of contamination, flooding – when planning how to improve things.
In a broader sense, integrated catchment management planning is a subset of environmental planning. It aims for sustainable, resilient outcomes – the quality of water entering the receiving environment, for example – through joint land and water management. An integrated approach contrasts with one that treats the two elements separately.
ICMPs also take into account the cyclical nature of an ecosystem, and use scientific and technical data to understand the natural world.
The Wellington City Council integrated catchment management plan
The global (meaning, 'applying to multiple catchments') stormwater discharge consent granted on 18 February 2011 required plans for Wellington’s catchments to be completed within 10 years.
What approach is Wellington Water taking?
We’ll develop the ICMPs in two stages. Stage 1 is complete and Stage 2 will be complete by 2021.
Stage 1 involved gathering data and making high level assessments of the effects of activities within the catchments and at the discharge locations. It also includes developing plans and a timetable for completing Stage 2.
Stage 2 is the development of the detailed management plans that will guide activity and record outcomes in the catchments.
What did Stage 1 deliver?
Stage 1 began with analysing the characteristics of Wellington’s 34 stormwater sub-catchments, based on:
- recreational use
- amenity values
- receiving environment characteristics
- legacy contamination
- effects of flooding
- surface water contamination
- potential wastewater contamination into stormwater
- future growth and its impacts
Work completed included:
- developing catchment summary maps (including boundaries, topography, soil, geology, drainage plans, outfall location details etc.) for 17 sub-catchments, from Horokiwi to Owhiro Bay. The total catchment area is about 24,400 ha, serving a population of about 157,000
- Summary reports for the 17 sub-catchments
- Data gathering including analysing wastewater reticulation impacts and issues, stormwater treatment practices, flooding incidents, network asset upgrades and upgrade implementation plans. The impacts of catchment activities are currently also being assessed
Where are we at now?
For the purposes of managing issues affecting receiving environments, we combined the sub-catchments into eight catchment areas.
Five of these are coastal receiving environment catchments: Lambton Harbour; Evans Bay; Island/Houghton Bay; Lyall Bay and East Coast (Seatoun, Karaka Bay).
The other three are stream-based catchments: Owhiro Bay, Kaiwharawhara and Ngauranga. Plans for these catchments will be prepared and in alignment with the Regional Plans.
Stage 2 involves preparing and implementing detailed management plans for each of the five coastal catchments. The plans will include:
- management options to minimise catchment issues
- preferred methods to manage network-related and land use issues
- statements of action and timeframes for undertaking preferred methods
- Developing plans for monitoring, evaluation, and reporting on the effectiveness of solutions implemented
If you have any questions about this work, contact us through firstname.lastname@example.org. We also produce regular newsletters on our progress (see the bottom of the page).