Date of interview: Wednesday, 1/28/2015

The last dam visited that day became the Tonoyama Dam, an arch dam owned by Kansai Electric Power Co (KEPCO). It is also known as the "Gogawa Dam". I don't remember anymore where and how we drove, but it seems that we had traveled quite a distance from the Shimanose Dam.

Gogawa Dam Observation Deck

The first place I arrived at was not the dam site but the Gogawa Dam observation deck. The official name of the dam is Tonoyama Dam, and because the name of the place is Gogawa, it is called Gogawa Dam by the local people. However, the fact that they do not deny the common name and accept the name "Gogawa Dam" is an expression of their kindness in wanting to be close to the people who live there, as well as their consideration for the local community itself.

Otherwise, I don't think they would have put it on the sign. I don't know whether KEPCO or the local community is responsible for the installation of these signs, but at least that is my impression. (The sign on the right looks like it was prepared by KEPCO, while the one on the left looks like it was prepared by the local government.)

As the cross-sectional view on the overview sign indicates, the Tonoyama Dam is a domed arch dam. It is also the first domed arch dam in Japan. It is no exaggeration to say that it is the culmination of Japan's technological prowess, and is said to be the cornerstone of the Kurobe Dam construction.

The Tonoyama Dam seen from the observatory can be captured straight downstream, but the distance makes it look a little small.

The mountains are overlapping each other, and the downstream area is just like a beautiful canyon. The Kanden black crest gate and the unique brownish embankment are very tasteful and elegant. It doesn't look much like an arch dam from here, by the way.

Also in the Kanden Blackorifice gateThe water that is released from it is also very beautiful. The water emanating from it is also very beautiful.

Incidentally, the Tonoyama Dam has four 7.150 x 5.670 m steel roller gates, two on each side, and two 7.756 x 5.650 m orifice gates in the center. The crest has six 6.770 x 2.279 m steel drop gates.

As the name implies, a drop gate is a gate that is lowered during discharge to allow overflow at the top of the gate. When normally closed, the gate is raised. It looks similar to a roller gate, but the normal and operating times are reversed.

The reason why a drop gate was adopted for the crest gate of the Tonoyama Dam is probably because it is an arch dam with a thin embankment and overflow section because the door body can be contained in a small space.

Dam site of Tonoyama Dam

I moved to the dam site. The dam site does not look like a dam, but just a parking lot, a building, and a crane. I wasn't sure if I could park my car in the parking lot, but since there was no other parking lot, I borrowed it for a while.

Tonoiyama Dam Dam Site — Toyama Damdam-site

A crane for loading and unloading materials.

To my surprise, the Tonoyama Dam is open for tours if you make a reservation in advance. I wonder if it is not possible to visit alone...

To all those wishing to visit the Tono Mountain Dam."

The top of the Tonoyama Dam and the dam management office are located further down from here, where an incline has been installed on a steep slope.

Just by looking at this, you can see that it was built on a very steep terrain.

I moved to the right and left on the right bank to see if I could somehow see the embankment. However, the trees were in the way and this was the best I could do. If I have a chance, I would like to visit the embankment. I would love to see the smoked silver dam at close range...that's what the Tonoyama Dam was like.

View of the top edge from the right bank

(extra) Cape Shiomisaki

Since this was my first visit to Wakayama, I wanted to see the southernmost point of Honshu, so I came to Cape Shiomisaki for the last stop of the day. Normally, you can visit the Shiomisaki Lighthouse, but since it was dusk, I only saw it from outside the gate.

Cape Tidal Basin is enveloped in evening darkness.

The southernmost stone monument in Honshu

My first visit to Wakayama was very enjoyable as everything I saw was fresh and new. There are many sightseeing spots, such as the ocean, mountains, and of course, many different types of dams to enjoy to the fullest. I left Cape Shiomisaki with a vow to return to Wakayama.

View of the Pacific Ocean from Cape Ushio

Tonoyama Dam Specifications

Location	Aza-Hinamiguchi, Aza-Agawa, Tanabe City, Wakayama Prefecture
River Name	Hikigawa River System Hikigawa River
Objective	P(Power generation)
Model	A(arch dam)
Bank height	64.500m
Bank length	128.692m
Dam volume	54,100 m3
Watershed Area	294km2
Reservoir area	137 ha
Total storage capacity	21,320,800 m3
Effective water storage capacity	13,152,900 m3
Dam operator	Kansai Electric Power Co.
Main body constructor	Maeda Corporation
Year of launch	1955
Year Completed	1957
Name of Dam Lake	Gogawa Reservoir