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Biodiversity ODI 2019-2024

What’s an ODI?

Outcome Delivery Incentives (ODIs) are a measure used by Ofwatt (a water industry regulator) to monitor Water Companies performances. They employ financial and reputational incentives for us to outperform our commitments and incur a financial penalty as well as bad press should we underperform.

Portsmouth Waters Biodiversity ODI is an assessment of how well we manage our Priority Habitat sites vegetation based on our ability to carry out annual planned work on time.

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Green Winged Orchids at disused Pump Station near Bishops Waltham, 2019

Priority Habitat definition

Priority Habitats under the Joint Nature Conservation Committee definition are semi-natural habitat types identified as being the most threatened and requiring conservation actions within the UK. Portsmouth Water Priority Habitat sites have been identified through our ecological surveys.

Grass cutting, coppicing, scrub management and pond maintenance are scheduled to take place at specific times of the year to enhance and protect Biodiversity on our sites taking into consideration the findings of the most recent ecological surveys. It is important management activities take place at appropriate times of the year to favour native species and diversity, and avoid disturbing species at important times such as within breeding bird season, whilst not infringing into the operational requirements of assets.

It is necessary to manage areas for biodiversity, rather than just simply leave them, to prevent infringement of lower-value habitats onto more high value local habitats. For example, chalk grasslands support a greater diversity of indigenous species and are maintained through grazing or cutting on several sites.

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Portsmouth Waters Roboflail at Bedhampton

Find out more about Portsmouth Waters Ecological Surveys and more on the Managing sites for Biodiversity page by pressing the button below:


Pond maintenance being undertaken by hand at Westergate, October 2021

A third of the most dominant species is removed before the first frost following wet weather to improve the diversity of life in the pond and enable more light to penetrate the vegetation.

Non-Priority Habitat sites

Sites that are not designated Priority Habitats, and therefore do not contribute towards the ODI, are also surveyed and managed for Biodiversity in the same way. We aim to improve the value of these sites and have recently carried out pond maintenance at Westergate to enhance the habitats value, planted a hedge at a Water Treatment Works facility, and maintained hedges at other reservoir and swallowhole sites.


Toad at Westergate Pond


Reservoir bank on Portsdown Hill, June 2016

Biodiversity ODI Progress 

The current ODI covers 29 sites running 2019 to 2024 and is audited by Natural England.

To pass the ODI Portsmouth Water must successfully complete at least 90% of all planned maintenance of its sites on time.

In 2021 Portsmouth Water achieved a 95 % pass rate and in 2022 a pass of 99.7 %. 

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