Water quality monitoring and investigations

The review of historical information in the FSG archive has demonstrated that there is very little historical data on water quality of the Fleet itself prior to 1996. This is largely because, historically, there has been no national or statutory requirement for the Environment Agency (EA) or its predecessors to monitor water quality of inshore water bodies such as the Fleet. Data which exist have been obtained under the requirement for EA to monitor effluent discharges to freshwaters (i.e. sewage effluent discharges into the streams entering the Fleet). Unlike the General Quality Assessments (GQA) for rivers (see NRA 1994), there is no national surveillance programme for inshore waters such as lagoons.

The Fleet has now been put forward by the EA as a >candidate polluted water (eutrophic)= to the European Community under the Nitrates Directive (91/676/EEC) for the review of such sites in 2001. The selection of the site was a result of concerns being expressed within the EA, but also by English Nature and the Fleet Study Group, over the nutrient status of the lagoon. Identification as a candidate site does not pre-judge the nutrient status or the key influences acting on it, but rather acts as a trigger for further investigation and monitoring to enable these questions to be answered with certainty. As a consequence, monitoring of the nutrient status of the Fleet and its inputs in future will have a statutory basis, ensuring routine monitoring takes place. The level of resources employed for monitoring and reporting will reflect EA regional priorities and the degree of the problem or potential problem of eutrophication at the site.

The table below provides an inventory of inputs to the Fleet. The following sections summarise the background, methods and results of monitoring or investigating several of these together with the Fleet itself in the following order:

Point sources (effluent discharges)

Streams (watercourses)

Receiving waters (the Fleet itself)

Additional monitoring of point sources, streams and the Fleet to support modelling

Estimation of inputs from diffuse sources (including land run-off and wildfowl)

Inventory of inputs to the Fleet lagoon (based on table 4 from EA 1998a)




Sewage Treatment Works Abbotsbury STW
Langton Herring STW
Swannery Restaurant
Moonfleet Manor Hotel
RETC Chickerell (now revoked)
RETC Bridging Hard (now revoked)
Watercourses East Fleet stream
West Fleet Stream
Rodden Stream
Portesham Mill Stream
Coward's Lake
Abbotsbury Mill Stream
Herbury Stream
Other Wildfowl
Portland Harbour
Land Run-off Land Run-off
Groundwater flow
Saline Intrusion
Aerial deposition

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