This River Blackwater drains small parts of the English counties of Hampshire and Wiltshire.

The Environment Agency measures water quality of the river systems in England.

Each is given an overall ecological status, which may be one of five levels: high, good, moderate, poor and bad.

There are several components that are used to determine this, including biological status, which looks at the quantity and varieties of invertebrates, angiosperms and fish.

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