Härtsfeldsee, reservoir in Germany

Härtsfeldsee, officially the Egautal flood retention basin, is a reservoir built by the Egau water association in 1972 near Dischingen. It covers about 11.5 hectares, reaches a maximum depth of 4.20 metres and holds two islands that may not be entered. The shore has a restaurant, a children's playground and water play equipment.

The Härtsfeldsee was built in 1972 by the Wasserverband Egau as the official flood retention basin Egautal. The Härtsfeldbahn railway, closed in 1972, ran directly east of the lake past Katzenstein station; in 2021 the Härtsfeld-Museumsbahn reopened between Neresheim and Katzenstein on that trackbed, with an extension to Dischingen planned.

Since 1997 the lake has hosted the annual Rock am Härtsfeldsee festival, a music event that draws visitors to the shore each year. The nearby Katzenstein station of the Härtsfeld-Museumsbahn, reopened in 2021 on the old Härtsfeldbahn line, adds a railway heritage element to outings at the water.

Three larger car parks sit close to the shore and serve as starting points for hikes; a bus stop on the Neresheim–Dischingen line is right at the lake. The two islands are breeding sites and must not be entered. The Härtsfeld-Museumsbahn runs on the old Härtsfeldbahn track immediately east of the water.

Two small protected islands within the reservoir serve as nesting sites for waterfowl that visitors can observe from the shore. These restricted areas demonstrate how the reservoir supports local wildlife conservation and offer birdwatchers excellent viewing opportunities without disturbing the birds.