Phosphate Pollution in the Rivers Wye & Lugg, Herefordshire

Growing concern over the health of the Rivers Lugg and Wye has caused Herefordshire Council to impose a moratorium on housing developments across the Lugg sub-catchment.

The River Lugg flows through the idyllic north Herefordshire countryside to intercept the River Wye at Hereford.  Both rivers are recognised as being internationally important for their unique character and rare wildlife, including otters, salmon, crayfish and lamprey.  The River Lugg is designated a Site of Special Scientific Interest (SSSI) for its entire length and sitting within the River Wye Special Area of Conservation (SAC).

Phosphate Pollution Herefordshire

In recent years, pollution especially from phosphates has impacted both rivers.  This has especially been the case for the River Lugg, which in 2019 the Environment Agency gave an overall ecological status of ‘Bad’ to ‘Poor’ for many sections and a ‘Failed’ chemical status.  Significantly high phosphate levels within the River Lugg have been identified as deriving from ‘diffuse’ sources, including surface water run-off from agricultural fields, and ‘point’ sources, including sewage outlets.  Consequently, the River Lugg contributes to dangerously elevated phosphate levels in the River Wye.

Leaching phosphates result in a process called eutrophication, which encourages algal bloom growth over the water surface.  This leads to a reduction in sunlight that kills aquatic plants and in turn results in reduced oxygen levels as bacteria decompose the dead plants.  This leads to declining aquatic insect, fish, invertebrate and bird numbers and, if left unabated, eutrophication can cause the river ecosystem to die resulting in a lifeless river.

Under the Conservation of Habitats and Species Regulations 2017, Herefordshire County Council (HCC) acts as the ‘Competent Authority’, whose role is to assess the potential impacts of proposed projects on the River Wye SAC.  This includes undertaking a ‘Habitat Regulations Assessment’ on all proposed planning applications within the River Lugg and Wye Sub-Catchments.  In its attempts to tackle this complex and worsening issue, HCC have declared that there is ‘limited scope for the approval of planning applications that give rise to additional damaging effects’.

Since July 2019, HCC have been working collaboratively with Natural England (NE), the Environment Agency (EA), Natural Resources Wales (NRW) and various other bodies as the Nutrient Management Board (NMB).  Together they have developed and manage a Nutrient Management Plan (NMP).  This aims to reduce phosphate levels in the River Wye SAC to below a set limit by 2027, in line with achieving ‘good’ ecological status set by the Water Framework Directive.  Following a review in December 2020, the NMP takes into account failing water quality in the Wye Sub-Catchment for Wales only and the River Lugg in Herefordshire.

Meanwhile, HCC in collaboration with NE have developed an Interim Phosphate Delivery Plan which outlines mitigation options for Phosphate removal, and legal and planning processes – vital for enabling proposed developments to proceed.

NE have advised that there is potential for positive appropriate assessment to help developments proceed if they can demonstrate that they will be ‘nutrient neutral’ or would lead to ‘betterment’.   Evidence of avoidance/mitigation measures must be given to prove either option.  To ensure that proposed housing developments do not contribute to increasing phosphates in the Lugg Sub-Catchment, via household foul water discharges to drainage fields, a seven point plan has been developed for small discharges to ground (less than 2m3 per day), which can be found here.


How Can EMS Geotech Help?

In our role as environmental consultants, EMS’s geo-environmental engineers have vast experience and local knowledge for assessing potential contamination risks.  This includes assessing potential risks, in line with NE’s Seven Point Plan, associated with proposed drainage fields and other infiltration devices for foul/waste-water disposal.  Foul and wastewater drainage relies on soil infiltration rates measured from percolation tests in accordance with BS 6297:2007.  Currently, meeting the NE’s Seven Point Plan only applies where percolation tests are required in the Wye Sub-Catchment, in Wales, and the River Lugg Sub-Catchment in line with the NMP.

Since July 2019 EMS have been involved with conducting percolation tests for foul/waste-water drainage that include meeting the NE’s Seven Point Plan for residential properties in Birley village, near Leominster.