Forecasting bathing water quality

UK Beach

managers

conference

Ian Dunhill Tidal water quality team

Environment Agency

14th May 2014

Day 1: Sample taken Day 2: Analysis starts

Day 5: Analysis Complete Day 7: Results at beach

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E.Coli Intestinal Enterococci

Sources of FIOs

90%

10%

Effect of discounting (152 sites)

Change 2013

Good Excellent 40

Sufficient Excellent 3

Sufficient Good 17

Poor Good 7

Poor Sufficient 19

Sites out of Poor 26

Other sites improved 60

If a site is classed as ‘Poor’ STP can’t be used

But the first classification won’t take place until 2015 .

Therefore STP can be used in 2014 and 2015 to avoid it becoming ‘Poor’

Defra responsibilities

Legislation – implementation of the rBWD into the BW Regs

Set policy

Designate sites

Controllers

Signage Electronic signage

Reporting

LA responsibilities

Fixed signage Permanent signage requirements

Number of previous year’s warnings

Reactive Signage Check BW explorer or text messages daily

Ensure sign(s) up by 10am

EA responsibilities

Determine suitable system – ‘developing system’

Determine suitable sites

Make forecasts Post on BW explorer

Send SMS text messages

Sampling and analysis

The water quality many sites is too good to have effective forecasts

Some sites not predictable using rainfall, other factors affect water quality such as groundwater contamination

Sites need to be affected by rainfall to be suitable for pollution risk forecasting (at present)

Forecasts will be made at all suitable sites

Only those sites with active signage will qualify for STP

As the method develops existing sites will come out of the scheme and new ones may be added

Note: We can’t guarantee that all sites currently in scheme will continue to be included

Site selection

Terminology

Pollution risk forecasting

Pollution risk warning

Short term pollution:

- requires management measures

STP Management measures

Signs must be displayed in the vicinity of the bathing water when a pollution risk warning is issued

The Environment Agency sampler must see an appropriately dated warning sign (or electronic sign)

A sample has to be taken by the Environment Agency after the STP event to confirm the end of the event.

If these conditions are met then up to 15% (3 in 20) of samples may be disregarded from classification.

In many cases this will improve the classification of the site by not counting the periods when advice against bathing was issued.

73.3% of three hourly weather is correctly forecast as 'rain

94% of three hourly temperatures are accurate to within +/- 2°C

78.4% of three-hourly weather is correctly forecast as 'sun’

Source: http://www.metoffice.gov.uk/about-us/who/accuracy/forecasts

How accurate are weather forecasts?

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08/09/2013 06:00 08/09/2013 18:00 09/09/2013 06:00 09/09/2013 18:00 10/09/2013 06:00 10/09/2013 18:00

FIO

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Axis Title

EC IE

EC 300 IE 180

Data collected by the Centre for Research into Environment and Health, University of Aberystwyth, as part of the Cloud to Coast Project, Reference: NE/I008306/1, funded by the Natural Environment Research Council, Medical Research Council, Economic and Social Research Council, Department of Environment, Food and Rural Affairs through the Environmental Exposures & Health Initiative (EEHI). '

How accurate are pollution risk forecasts?

Beach samples

Quality distribution, daily sampling

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E-coli Intestinal enterococci

Warnings

Daily procedure

5th May to 30th September

Web page will be updated by 9am with the day’s forecasts.

These will then also be sent as a text message to registered mobile phone numbers and electronic signs

By 10am warnings will have to be displayed at bathing waters

The sampling programme will continue without alteration, 20 times per season

Additional samples for STP Most of the time warnings won’t require any additional samples.

When we have issued a warning and this coincides with a statutory sample and a sign is present additional samples will be required.

The directive requires us to take a sample to “confirm the pollution has ended”, the confirmation sample.

The directive also specifies that “If necessary to replace a disregarded sample, an additional sample is to be taken seven days after the end of the short-term pollution” the replacement sample: this year only.

Once a year’s classification has been made samples can’t be added or removed at a later date from that year’s data

Signage requirements Fixed: [In an easily accessible place in the vicinity of the bathing water] Notification that the bathing water is subject to short-term pollution, An indication of the number of days on which bathing was prohibited or advised against during the preceding bathing season because of such pollution. Conditions likely to lead to short-term pollution,— the likelihood of such pollution and its likely duration, the causes of the pollution and measures taken with a view to preventing bathers' exposure to pollution and to tackle its causes.

Reactive: A warning whenever such pollution is predicted or present “A sign visible to the public, which states that there is an increased risk of pollution, expressed in those or other words and that sign is dated for the day on which you are sampling. “

Note: We won’t be able to be disregard samples taken during

STP events without the sampler observing the appropriate

warning sign (fixed and reactive)

Signage

Warning messages

No water quality warning issued

Risk of reduced water quality due to heavy rain (or whatever else)

No water quality forecast available

25/07/2014: NO WATER QUALITY WARNING ISSUED

25/07/2014: RISK OF REDUCED WATER QUALITY DUE TO HEAVY RAIN (or whatever else)

NO WATER QUALITY FORECAST AVAILABLE

Electronic signs

Pollution risk forecasting Not predicting actual water quality

Predicting an increased risk of encountering reduced water quality

There is always a risk of unfavourable water quality, but after rainfall this risk increases

In most cases warnings not linked to discounting

Project in it’s early stages, it will evolve over time

Hope eventually to combine warnings from CSO alerts into system

cBWD: Fixed limits rBWD: Percentile evaluation