Changdang Lake

　　Changdang Lake, also known as Tao Lake, is situated approximately 9 kilometers southeast of Jintan City and spans both Jintan and Liyang. It is one of the ancient lakes that originated from the Taihu Lake system. In ancient times, the lake covered a much larger area, extending north to Jincheng’s Jianchang and south to Liyang’s Nanhe, spanning over 50 kilometers from north to south, hence it was referred to as "Changtang" (Long Pond) as early as the Jin Dynasty. Over the years, due to land reclamation, the lake has been reduced to just 8,500 hectares, most of which lies within Jintan. Li Daoyuan’s Commentary on the Water Classic refers to this lake as one of the “Five Ancient Lakes,” part of the Taihu Lake water system. Tao Lake has long been a scenic destination in Jintan, with the “Moonlit Night of Tao Lake” once listed as one of the Eight Scenic Spots of Jinsha (Jintan). The lake features a clear blue base, dotted with fishing boats, swaying reeds, and lush grass, offering picturesque scenery. Major cultural and historical sites around the lake include the underwater stone path, ancient wells at the lakehead, Zhou She (where the Three Kingdoms general Zhou Yu once set camp), Baimitang, and Pumen Chan Temple. Among these, Pumen Chan Temple is built on Dafu Mountain, known as the “Little Putuo.” The temple complex is nestled among staggered pavilions, verdant trees, and lush grass, complemented by the shimmering lake and mountain views, creating an exceptionally stunning landscape. Dafu Mountain is a rocky hill with an elevation of 35.6 meters and covers an area of 0.15 square kilometers. It once stood isolated in the lake, appearing to float from afar, hence its name. Today, Dafu Mountain is connected to the mainland, and cars can drive all the way to the mountaintop.

　　The bottom of Changdang Lake is flat, with an average depth of 1.1–1.2 meters. Its pH value consistently ranges between 7 and 8, making it highly suitable for crustacean aquaculture. The lake is abundant in freshwater resources, enjoys clean and unpolluted water, and teems with aquatic life such as water plants, snails, and clams. It is especially rich in local specialties like Yuzhua crabs (Changdang Lake crabs), rice shrimp, whitebait, and fish maw. Historical records from the Guangxu-era Jintan County Annals describe the lake’s bounty with the phrase “half the scoop of water is fish.” The lake also hosts various waterfowl such as yellow buntings, bamboo partridges, and wild ducks. After the Cold Dew solar term, flocks of bamboo partridges and wild ducks gather here. As the local folk song goes: “When they take flight, the sky disappears; when they land, they cover the lake. When three days of cold strike, hundreds of flocks huddle close (with six birds to a flock).”

　　Changdang Lake is like a “mirror” embedded in the plains of southern Jiangsu. In recent years, in this “Golden Lake and Silver Bay” where “gold is harvested at sunrise and silver at night,” the people of Jintan—hometown to the renowned Chinese mathematician Hua Luogeng—have demonstrated their unique ingenuity by pioneering a new concept in freshwater aquaculture: the “pastoral-style” crab farming using enclosures on the lake. This innovation has earned Jintan the title “Home of the Chinese Mitten Crab.” With 60,000 acres of enclosed crab farming, the industry generates over 200 million yuan annually for Jintan, truly making Changdang Lake the city’s “mother lake.”

　　However, in recent years, the “mother lake” has been under increasing strain: the density of enclosures within the lake is too high, leading to noticeable eutrophication trends; meanwhile, various forms of pollution from the lakeshore have led to deteriorating water quality. To address this, in early 2004, the “Protect the Mother Lake” campaign was launched in Jintan. The Jintan Municipal Party Committee and government, with a focus on sustainable development, introduced the Changdang Lake Ecological Environment Protection Plan to comprehensively restore the lake’s ecological health. Measures included reducing the enclosed water surface area by 20,000 acres within two years, establishing wetland ecological reserves around the lake to enhance its self-purification capacity, and strictly curbing pollution from industrial, catering, and domestic waste entering the lake. These efforts aim to restore the lake’s clarity and vibrant blue color, ensuring it remains a true “mirror” on the vast plains of southern Jiangsu.