A model‐based assessment of non‐compliance of phosphorus standards for lakes in England and Wales

Abstract

High phosphorus concentrations causing eutrophication will prevent many lakes in England and Wales from reaching good ecological status by 2015 according to the EC Water Framework Directive (WFD). The aim of this study was to estimate the percentage of lakes in England and Wales that are likely to fail recently agreed WFD phosphorus standards. As measured lake phosphorus concentrations are only available for a small number of lakes a model-based approach was adopted. This involved estimating phosphorus loads from a wide range of sources including agricultural loads, sewage effluents, septic tanks, diffuse urban sources, atmospheric deposition, groundwater and bank erosion. Lake phosphorus concentrations were predicted using the Vollenweider model, and the model framework was satisfactorily tested against available observed lake concentration data. Applying the model to all lakes in England and Wales greater than 1 ha, it was estimated that under current conditions, roughly two thirds of the lakes would fail good ecological status with respect to phosphorus. According to our estimates, agricultural phosphorus loads represent the dominant source for the majority of catchments, but diffuse urban runoff also is important in many lakes and sewage effluents are the most frequent dominant source for lake catchments greater than 100 km 2 . Required reductions of phosphorus loads to increase the number of lakes achieving good ecological status and potential delays because of internal loading and biological resistances are briefly discussed.

Projecting the Impact of Regional Land-Use Change and Water Management Policies on Lake Water Quality: An Application to Periurban Lakes and Reservoirs

“…Thus, reducing urban covers in small agricultural seepage lakes catchments may negatively act on their eutrophication status if urban land cover is converted to agricultural land cover. This observation is also consistent with the fact that large catchments are more likely to be exposed to urban point source pollution, whereas smaller catchments are generally mainly subjected to diffuse pollution [75].…”

“…The pessimistic forecast provided by our approach illustrated the fact that remediation measures, as currently planned by governmental agencies, are likely to only have a marginal impact on improving the eutrophication status of surface waters, which is unfortunately consistent with scenario analysis in other European countries [75], [77]. If the eutrophication status of surface waters is to be significantly improved, setting costly large-scale (e.g., regional) nutrient abatements targets might be inefficient and should be, at least, complemented or replaced by catchment-specific analyses of nutrient sources associated to appropriate remediation measures [64], [78].…”

“…Though 74% of the observations of drainage lakes indicated a Chl a concentration greater than 25 µg L −1 , only a small proportion (3.3%) of observations of seepage lakes indicated values exceeding this threshold value (Table 2). Overall, 66% of the sampled lakes (32 out of 48) are considered to be eutrophic to hypertrophic (Table S1), which is very similar to other area European countries (e.g., England and Wales [75]). …”

Sustaining recreational quality of European lakes: minimizing the health risks from algal blooms through phosphorus control

“…This is particularly useful for current or future predictions of recreational quality at broad geographical scales. Nutrient data are much widely available than phytoplankton data for many lakes and reservoirs and can also be readily modelled from catchment data (Duethmann et al 2009). So, based on an agreed risk level of exceeding the cyanobacterial threshold, the parameterized models can also be used to assess recreational quality across broad geographical scales.…”

Water Quality Characterisation and Restoration Measures of University of Nottingham Malaysia Campus (UNMC) Lake

“…On the other hand, comparing the results with this classification, UNMC Lake can be said to be eutrophic. High phosphorus concentration in water causing eutrophication prevents lakes from attaining good ecological status [13]. The range of soluble reactive phosphate levels in the UNMC Lake is between 0.006 to 0.009 mg/L in all the sampling points with the inflow 1 (MLI1) recording the highest value of 0.009 mg/L (Figure 4).…”