Not a safe place to swim, in , a UC Davis graduate student was pulled into the glory hole while swimming and drowned. The dam and spillway were constructed between and , choking off Putah Creek and drowning the remains of the town of Monticello. At very low water levels, the foundations of the town can be seen in parts of the lake. The outside diameter is 72 feet, slowly narrowing to 28 feet at the exit. While this is the largest drain of its kind, there are other Glory Hole spillways around the world, including one in Whiskeytown Lake, and in Northern California.
Lake Berryesa Glory Hole: A dam explanation
Some say it looks like a toilet being flushed; in more generous interpretations, it is a beautiful inverted fountain. In a rare occurrence, the water level in the Lake Berryessa reservoir, 75 miles north of San Francisco, has risen so much that it is pouring into a ft-deep circular pipe constructed in its corner. The 72ft diameter pipe, known as Morning Glory Spillway, or simply Glory Hole, takes in water like a drain, once the reservoir is filled over capacity, and shoots it into a creek below the Monticello Dam. Northern California has seen heavy precipitation for weeks. Thousands of people have been evacuated from their homes due to risks of floods near the town of Guerneville, and highways around the region have been shut down because of the downpours.
The Glory Hole of Lake Berryessa
Lake Berryessa is currently the seventh largest man-made lake in California. Water from the reservoir primarily supplies agriculture in the Sacramento Valley downstream. The dam is noted for its classic, uncontrolled morning-glory-type spillway. Locally, the spillway is also known as the "Glory Hole".
Water is flowing for the first time in over a decade into the foot diameter hole due to the recent storms in California. The unique spillway operates similarly to a bathtub drain. Heavy downpours are swelling creeks and rivers and bringing threats of flooding in California's already soggy northern and central regions.