MID-STREAM ISLANDS

Three mid-stream islands were constructed near footbridge 1 (see map 2). The method of construction was similar to the river narrowing work, and in time the structures would develop as islands with vegetation. The top level of the islands were planned to be 150-200mm above water level.

Following the construction of the two upstream islands they were surrounded with flint reject topped with gravel as part of riffle 3. The braided flow over the riffle provides a juvenile trout habitat within the spawning area created. The backwater effect also improves access for spawning fish to the side channel which enters the river immediately upstream from the islands.

Each of the islands formed a point at the upstream end, but set at a slight angle to the river flow. They were 2-3m long and some half metre wide. Each was built around a frame of 7 stakes driven into the river bed. The third island was in a metre of water, and as noted above the other two had been set where riffle 3 was to be placed. The islands quickly collected silt, leaves and much water cress.

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