The ICW concept addresses multiple ecosystem service outcomes associated with wetland processes. It takes a ‘landscape fit’ approach, reinstating cascades of shallow, vegetated wetland cells within natural, aesthetic and working landscapes. Linked benefits include wastewater processing, hydrological buffering, regeneration of flows in watercourses, public access to attractive regenerated wetland landscapes, silt and nutrient interception, and the recovery of lost landscapes and populations of aquatic species such as otters, brown trout, salmon, sea trout and eels. Networks of ICWs in the Anne Valley now support farm profitability, manage sewage from the household or the industrial unit and up to the village scale and provide leisure opportunities and regenerate the ecology, recreational and aesthetic value of a formerly much degraded catchment ecosystem. Widespread uptake of ICWs has reanimated the Anne Valley, ecologically, socially and economically, with extensive scientific verification of ecosystem service outcomes.
ICWs have been adopted elsewhere in Ireland for a variety of reasons. These include the treatment of landfill leachate, hotel wastewater and diffuse inputs in a city centre context, with many ecosystem service co-benefits. Regulatory agencies, particularly the Irish EPA, have resisted granting consents for the installation of ICWs, due largely to the narrow terms under which these licences are issued and the exclusion from consideration of inputs to their operation and the wider suite of benefits that they deliver. However, ICW design has become incorporated into Irish Government guidance under the Water Services Investment Programme 2010-2012 which recognises the potential for ICWs to reverse former declines in the ecosystem services of lost natural wetlands. ICWs represent a low-input, multi-service output ‘systemic solutions’ approach contributing to sustainable development by optimising benefits across a range of ecosystem services and beneficiaries, increasing their net economic value.
New York City’s water supply
New York City derives its water supply from the Cat/Del (Catskills and Delaware) catchments. A contract was negotiated between urban water users and farming and other rural communities in the Cat/Del catchments, in order to undertake measures to maintain high quality water. This has become one of the largest global ‘payment for ecosystem service’ (PES) schemes. This arrangement was formalised as a comprehensive Memorandum of Agreement in 1997. Under the terms of the MOA, the city committed funds of approximately $US350 million (£190 million) with additional investment in a watershed protection programme costing approximately $US1.3 billion (£700 million).
Though substantial, these figures represent only a small fraction of the financial costs and environmental impacts of alternative conventional engineered solutions to treat more contaminated raw water abstracted downstream. This partnership approach, linking rural and urban stakeholders, is key to maintaining New York City’s pristine water quality and the viability of farming for the foreseeable future.