I popped down to the Dam after work and there were swarms of these caddisflies around the lake. I think this impressingly long-antennaed species is Mystacides longicornis.
(I'm aware that uploading images from my camera to my iPad wirelessly, as I've done here, leads to a reduction in image quality. On landscapes that's not so significant but you can tell the difference on pictures like this, so I may change it to a proper upload on my pc later. UPDATE: image replaced with same one but uploaded through PC.)