Case study:Bristol Frome Diffuse Pollution Project

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Location: 51° 34' 47", -2° 27' 0"
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Project overview

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Status Complete
Project web site
Themes Habitat and biodiversity, Land use management - agriculture, Water quality
Country England
Main contact forename Harriet
Main contact surname Alvis
Main contact user ID User:H.alv
Contact organisation Bristol Avon Rivers Trust
Contact organisation web site http://www.bristolavonriverstrust.org
Partner organisations
Parent multi-site project
This is a parent project
encompassing the following
projects
No
Valuable topsoil and nutrients entering the Ladden Brook from agricultural run-off

Project summary

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The Bristol Frome Diffuse Pollution Project is a project led by Bristol Avon Rivers Trust (BART) from June 2015 – March 2016, as part of the Bristol Avon Catchment Partnership. The project has been conducted in partnership with the Farming and Wildlife Advisory Group (FWAG) South West and the farmers and landowners along the Ladden Brook and Bradley Brook which form the headwaters of the Bristol Frome. It has been driven by Water Framework Directive classifications that have shown a need to identify issues and take actions to contribute towards a reduction in the levels of sediment and nutrients entering the Bristol Frome and its tributaries.

Reports commissioned by the Environment Agency suggested that a focus on agricultural practices within the streams of the upper Bristol Frome catchment should be carried out as a priority and pre-requisite to further improvement works. Therefore, the Bristol Frome Diffuse Pollution Project chose to focus on two agriculture dominated brooks, The Ladden and Bradley Brooks in order to achieve the overall aim of reducing nutrient and sediment inputs from diffuse agricultural sources.

Baseline and wet weather monitoring, farmer engagement and advisory visits, walkover surveys and past Environment Agency data was used to assess areas for capital improvements to be made that would have the greatest impact for the timescale and funding available. These were decided upon as fencing to reduce bank erosion and an in-ditch wetland to separate clean water from dirty yard run-off that was previously entering the brook.

Monitoring surveys and results

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Baseline and wet weather phosphate, turbidity and dissolved oxygen monitoring and invertebrate monitoring.

Main findings:

-Phosphate concentrations measured during this study were high enough to cause WFD failure at every site, suggesting high levels of diffuse pollution throughout the catchment.

-Particularly high phosphate concentrations recorded during during dry-weather conditions in the lower reaches of the Ladden Brook, were accompanied by low dissolved oxygen and elevated turbidity. This requires further investigation as a high priority.

-Historic DO concentration in the Bradley Brook has steadily increased over the last 35 years, suggesting an improvement in water quality over time.

-The flood defence impoundment at Three Brooks Nature Reserve appears to be causing significant issues for turbidity and dissolved oxygen upstream in the Bradley Brook.

-There is a need for a future regular monitoring scheme on the brooks, including during wet weather events, if pollution sources are to be identified and resolved.

Lessons learnt

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Both the Ladden and the Bradley Brooks are suffering biologically and physico-chemically due to agricultural run-off. Whilst the improvements made during the course of this project will help to reduce these issues to some extent, the catchment requires a much larger programme of improvements in order to make a measurable difference.


Image gallery


In-ditch wetland to seperate clean water from dirty water before entering the Ladden Brook
Fencing to reduce bank erosion and silt pollution
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Catchment and subcatchment

Catchment

River basin district Severn
River basin Bristol Avon and North Somerset Streams

Subcatchment

River name Bradley Bk - conf Stoke Bk to conf R Brist Frome
Area category 10 - 100 km²
Area (km2)
Maximum altitude category Less than 100 m
Maximum altitude (m) 83
83 m
0.083 km
8,300 cm
Dominant geology Calcareous
Ecoregion Great Britain
Dominant land cover Arable and Horticulture
Waterbody ID GB109053027570



Site

Name Ladden & Bradley Brooks
WFD water body codes GB 109053027590 & GB109053027570
WFD (national) typology
WFD water body name
Pre-project morphology
Reference morphology
Desired post project morphology
Heavily modified water body No
National/international site designation
Local/regional site designations
Protected species present No
Invasive species present No
Species of interest
Dominant hydrology
Dominant substrate
River corridor land use Agricultural
Average bankfull channel width category
Average bankfull channel width (m)
Average bankfull channel depth category
Average bankfull channel depth (m)
Mean discharge category
Mean annual discharge (m3/s)
Average channel gradient category
Average channel gradient
Average unit stream power (W/m2)


Project background

Reach length directly affected (m)
Project started
Works started
Works completed
Project completed
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Total cost (k€)
Benefit to cost ratio
Funding sources

Cost for project phases

Phase cost category cost exact (k€) Lead organisation Contact forename Contact surname
Investigation and design
Stakeholder engagement and communication
Works and works supervision
Post-project management and maintenance
Monitoring



Reasons for river restoration

Mitigation of a pressure Land drainage
Hydromorphology
Biology
Physico-chemical
Other reasons for the project


Measures

Structural measures
Bank/bed modifications
Floodplain / River corridor
Planform / Channel pattern
Other Agricultural/Farming improvements, improvement of structure of agricultural land
Non-structural measures
Management interventions Farm advice and plans
Social measures (incl. engagement) interacting with farmers
Other Survey work


Monitoring

Hydromorphological quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative

Biological quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative

Physico-chemical quality elements

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Any other monitoring, e.g. social, economic

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative


Monitoring documents



Additional documents and videos


Additional links and references

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Supplementary Information

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