The History of Nozori Dam
The Nakatsugawa River and the Creation of Lake Nozori
The Nakatsugawa River begins in the northern part of the Kuni area of Nakanojo and flows through Gunma, Nagano, and Niigata prefectures. It passes through the remote mountain region known as Akiyama-go before eventually joining the Shinano River in Tsunan, Niigata Prefecture.
Lake Nozori is located near the source of the Nakatsugawa River, while Nozori Dam holds back the water at the northern end of the lake.
Before the dam was constructed, the area consisted mainly of wetlands with several small ponds known collectively as Nozori-ike. During the Taisho period in the early 20th century, the electricity company Shin’etsu Electric planned to use the water resources of the Nakatsugawa River, including Nozori-ike, for hydroelectric power generation and obtained the necessary water rights.
Following a series of corporate mergers, these water rights were eventually inherited by Tokyo Electric Power Company. As the company redeveloped hydroelectric facilities along the Nakatsugawa River, construction of Nozori Dam began in 1953 and was completed in 1956.
Japan’s First Rockfill Dam Built for Hydroelectric Power
Nozori Dam is notable as the first rockfill dam constructed in Japan specifically for hydroelectric power generation. During its construction, a method known as rock dumping was used. Large rocks were dropped from a height, and the impact of the falling rocks helped compact the dam.
Because this construction method could result in considerable settlement, modern rockfill dams generally use heavy machinery such as road rollers for compaction instead.
Another distinctive feature is the upstream face of the dam. It is completely covered with reinforced concrete to prevent water from passing through the dam. Only four dams in Japan use this particular type of construction, making Nozori Dam an interesting destination for visitors interested in civil engineering and infrastructure.
The Natural Beauty of Lake Nozori
Lake Nozori can be reached by traveling north from the direction of Kusatsu Onsen along National Route 405 and crossing Nozori Pass. After passing through the mountain pass, visitors are greeted by the expansive lake surrounded by forests.
The lake’s clear blue surface contrasts beautifully with the surrounding natural woodland. Although Lake Nozori is an artificial reservoir created by a dam, its tranquil setting and natural appearance give it the atmosphere of a remote mountain lake.
The lake and its surroundings are part of Joshin’etsukogen National Park, while the nearby national forest is designated as the Nozori Nature Recreation Forest. In 2005, Lake Nozori was selected as one of Japan’s 100 Selected Dam Lakes in recognition of its scenic and environmental value.
Walking Trails and Mountain Activities
The walking trails around Lake Nozori have also been selected among Japan’s notable walking routes. The area serves as a starting point for hiking toward Mt. Shirasuna and other mountains along the border region between Gunma and Nagano.
These trails allow visitors to explore the highland environment at a slower pace while enjoying forests, mountain views, streams, and seasonal vegetation.
Summer Alpine Flowers
Summer is one of the most beautiful seasons around Lake Nozori. The cool highland climate creates ideal conditions for a variety of alpine and mountain plants.
Among the most recognizable flowers is Nozori Kisuge, the local name for the daylily commonly known in Japan as Nikko Kisuge. Renge azaleas also bloom around the lake, adding vivid colors to the green mountain landscape.
Fishing is another popular activity. Rainbow trout and Japanese char are stocked in the lake, and visitors with the appropriate fishing permit can enjoy fishing. However, the water remains cold even during summer, so the lake is not suitable for swimming.
Access to Nozori Dam and Lake Nozori
Seasonal Access
Access to Nozori Dam and Lake Nozori is generally limited to the main tourism season, from approximately May 1 through October 20. The high elevation means that winter conditions can make access difficult.
During the accessible season, buses operated by Nakanojo Town connect JR Naganohara-Kusatsuguchi Station with the lake area. The route passes through areas including Roadside Station Kuni and Hanashiki Onsen, taking approximately 1 hour and 15 minutes to reach the lakeside bus stop.
Along the route, travelers can also see other dams, including Shinaki Dam (Lake Joshu-Yunoko) and Shirasuna Dam. These belong to the Tone River water system, whose waters ultimately flow toward the Pacific Ocean.
National Route 405 and the “Dotted National Route”
National Route 405 does not continue as a normal road beyond the Nozori Dam area toward Kirami Onsen, located deep in Akiyama-go. The route becomes an inaccessible section followed by rugged mountain trails.
Because of this unusual situation, this section is sometimes referred to as a “dotted national route” in Japan. It is not suitable for ordinary sightseeing drives, but it is an intriguing challenge for experienced hikers and mountain enthusiasts.
Distinctive Features of Nozori Dam
A High-Altitude Dam
The top of Nozori Dam stands at an elevation of approximately 1,517 meters. Before the completion of Minamiaiki Dam, whose crest is approximately 1,532 meters above sea level, Nozori Dam was known as the highest-elevation dam in Japan.
The dam crest is also used as a road, allowing vehicles and pedestrians to cross to the opposite side. However, the road is narrow, so vehicles need to pass each other carefully and use the available space appropriately.
Water Release Facilities
A pipe beneath the dam carries water drawn from the lake and allows it to be released downstream. The facility has a maximum discharge capacity of approximately 6 cubic meters per second.
These engineering features, combined with the dramatic mountain setting, make Nozori Dam an interesting destination for visitors who enjoy both natural landscapes and Japanese infrastructure.
When to Visit Nozori Lake
Spring brings fresh greenery to the surrounding mountains as the highland environment emerges from winter.
Summer is particularly attractive for hiking and enjoying alpine flowers. The cool temperatures at this elevation provide a refreshing escape from the warmer lowlands.
Autumn brings colorful foliage to the surrounding forests, creating a striking contrast with the blue surface of Lake Nozori.
Because winter access is restricted, travelers should check road and transportation conditions before planning a visit outside the main sightseeing season.
Why Visit Nozori Dam and Lake Nozori?
Nozori Dam and Lake Nozori offer a rare combination of engineering heritage and highland nature. Visitors can enjoy a beautiful mountain lake, forests, alpine flowers, hiking trails, fishing, and impressive views while also learning about one of Japan’s early rockfill dams built for hydroelectric power.
The area’s remote atmosphere makes it particularly appealing to travelers who want to experience the quieter side of Japan. Rather than a conventional urban tourist attraction, Nozori provides an opportunity to explore a spectacular mountain environment within a national park.
For visitors traveling around Kusatsu, Shima, and northern Gunma, Lake Nozori is a memorable destination for experiencing the natural beauty of Japan’s highlands.
Exploring Gunma
Gunma Prefecture is home to a wide variety of landscapes, from volcanic mountains and highland lakes to famous hot spring towns, historic sites, gardens, museums, and local food.
The main tourism areas of Gunma include Kusatsu & Shima, Shibukawa & Ikaho, Tatebayashi & Ota, Takasaki & Maebashi, Tomioka & Shimonita, Oze & Numata, Kiryu & Akagi, and Minakami.
For travelers interested in Japan’s mountains, hot springs, seasonal scenery, rural culture, and distinctive engineering heritage, Nozori Dam and Lake Nozori offer a fascinating destination away from the country’s major urban tourist routes.