| Okutadami Dam | |
| Location Map: | Japan |
| Coordinates: | 37.1533°N 139.25°W |
| Country: | Japan |
| Location: | Uonuma |
| Construction Began: | 1953 |
| Opening: | 1961 |
| Owner: | Electric Power Development Company |
| Dam Type: | Gravity |
| Dam Height: | 1570NaN0 |
| Dam Length: | 4750NaN0 |
| Dam Volume: | 16360000NaN0 |
| Dam Crosses: | Tadami River |
| Res Name: | Lake Okutadami |
| Res Capacity Total: | 6010000000NaN0 |
| Res Capacity Active: | 4580000000NaN0 |
| Res Catchment: | 5950NaN0 |
| Res Surface: | 11500NaN0[1] |
| Res Elevation: | 7500NaN0 |
| Plant Hydraulic Head: | 120 MW units: 1700NaN0 200 MW unit: 164.20NaN0 |
| Plant Commission: | 1960, 2003 |
| Plant Turbines: | 3 x 120 MW, 1 x 200 MW Francis-type |
| Plant Capacity: | 560 MW |
The Okutadami Dam (奥只見ダム) is a concrete gravity dam on the Tadami River, 260NaN0 east of Uonuma on the border of Niigata and Fukushima Prefectures, Japan. The primary purpose of the dam is hydroelectric power generation and it supports a 560 MW power station which is the largest conventional hydroelectric power station in Japan. The dam also forms the second largest reservoir in Japan, next to that of the Tokuyama Dam.[2]
Construction on the dam began and its original 390 MW power station was commissioned 2 December 1960. The rest of the project was complete in 1961. Between 1999 and 2003, the power station was expanded, adding 200 MW in installed capacity. In addition, a 2.7 MW generator was added to ensure a flow of 2.50NaN0 downstream for environmental purposes.[3] Along with the same power plant upgrade, a second Kaplan turbine-generator was added to the 830NaN0 tall Otori Dam's power station downstream at . This generator has an 87 MW capacity in addition to the existing 95 MW unit, for an installed capacity of 182 MW.[4]
36 houses were submerged.
The Okutadami Dam is a 1570NaN0 tall and 4750NaN0 long concrete gravity dam with a structural volume of 16360000NaN0. Sitting at the head of a 5950NaN0 catchment area, the dam creates a reservoir with a 6010000000NaN0 capacity of which 4580000000NaN0 is active (or "useful") storage. The reservoir has a surface area of 11500NaN0. The power station is underground and located on the right bank of the river next to the dam's abutment. It consists of two caverns, one for the original power station and another adjacent for the expansion. After being received by the dam's intake, water supplied to the original power plant travels down three penstocks 185- in length before reaching an individual 120 MW Francis turbine-generator. The 200 MW Francis turbine-generator receives water via a 2800NaN0 long penstock. After water is processed through the generators, it travels down two tailrace tunnels before being discharged over 30NaN0 downstream at the upstream edge of the Otori Reservoir.[5]
Minami Echigo Kankō Bus (Okutadami Dam Line and Express Okutadami Dam Line)
Aizu Bus (Nakayama Tōge and Oze Line - No.011)[7]