Lake Rawa Pening (literally meaning 'Clear Swamp', from the Javanese Bening) is a lake in the Ambarawa Basin in Central Java, Indonesia. With an area of ​𔁰,670 hectares it occupies the District of Ambarawa, Bawen, Tuntang, and Banyubiru. Rawa Pening is located in the lowest basin slopes of Mount Merbabu, Mt. Telomoyo, and Mount Ungaran.
The lake is experiencing rapid silting. Once the fishing grounds, are now almost the entire surface is covered with water hyacinth marsh. This weed has also been covered Tuntang River, especially in the upstream. Efforts addressing invasive species is done by doing the cleaning as well as training in the use of water hyacinth handicraft, but the pressure is very high plant populations.
This swamp popular as a tourist attraction fishing and water sports facilities. But lately, fishing boat moves too difficult.

Last week, thousands of volunteers participated in the follow-  ?Gugur Gunung Resik-Resik Rawa Pening? or Lake Rawa Pening Cleaning Up Movement in the morning until noon it initiated a number of communities in the District of Semarang one by one direction as well as the division of the task group was read to the committee on the outskirts of Rawa Pening or in between the railroad tracks that connects between Ambarawa and Semarang District Tuntang. Before thousands of people from all the elements, as well as the signing ceremonies held in a white cloth that had been prepared. They were each spread. Starting from the elements of nature lovers community (the environment), military, police, SAR, Disaster Management Agency (BPBD), student groups, to the general public to mingle with the same goal which is to clean garbage and water hyacinth that are around the Lake Rawa Pening. Background clean-up Rawa Pening was more to see the real condition of the lake which is a growing concern. Besides dirty because of the garbage even more overgrown with water hyacinth. Sedimentation also be a serious threat to its existence.

Water hyacinth population very rapidly making natural sedimentation in the lake is also faster. So it is very disturbing fisheries and agricultural productivity. Sedimentation greatly affect fish populations and for agriculture, this resulted in sedimentation swamp rice fields submerged in water. Not to mention, water hyacinth also nest rat. Sedimentation and water hyacinth population is increasingly becoming a social threat. Due to increasingly threaten the livelihood of citizens. Neither the livelihood of fishermen and farmers in Rawapening.

Meanwhile, the cleaning process is done by herding swamp weed water hyacinth is d middle of the swamp using speedboats and outboard boats. After arriving at the edge of the swamp, water hyacinth is removed and collected in one area by volunteers.