municipality of Savski Venac and covers . Since the early 1980s there is a constant ecological problem due to the massive pollution of the bay as a result of the polluted waters of the Topčiderka river. The garbage and highly polluted silt fills the bay and creates shoals. During low-tide, the bay is unusable for the boats in the marina, located in the middle of the bay or for the kayakers of Partizan and Crvena Zvezda who use the bay for practice. The silt is up to thick, smells bad and is poisonous so the swimming in the bay is forbidden. In 2011 the estimated amount of garbage sludge in the bay was . The sludge cannot simply be dredged and thrown in the Sava further downstream due to the toxicity. The plan to build a treatment plant on the bank near the Belgrade Fair which would detoxicate the sludge and produce fertilizer from it was scrapped due to the high costs. At the time, the silt is being dredged and vegetation cut just enough to make it navigable for the small boats in the marina. The bay was partially dredged in 2016. The pollution of the bay continued, including two atmospheric precipitation collectors which overspill into the bay, to which the fecal sewage is illegally connected, and the bay was described as the ecological time bomb. In December 2019 the winning project was announced. It includes the transformation of the bay into the artificial whitewater and the proper marina. A project by Aleksandar Nedeljković, named "Flight of the gull" envisions the reconstruction and elevation of all embankments along the bay's banks, turning them into the vertical retaining walls. Pumps for the creation of the whitewater by day, would be used to purify the water by night and prevent the sludge from depositing on the bottom. Proposed name for the marina and sports center is "Whitewater Arena". However, this project, just like some others from the competition (conducting the Topčiderka directly into the main Sava riverbed by the pipes) does not tackle the problem of the already existing sludge deposits or the toxicity of the waste. Also, it was outright labeled as way too expensive, even by its authors (up to €70 million). An experiment was conducted when the water from the bay and river was pumped into the special pools in the nursery gardens of the state company for