Tomoe River (Aichi Prefecture) Complete Guide: Characteristics, Basin, and Fishing Information of the Yahagi River and Toyokawa Water Systems Thoroughly Explained
The Tomoe River (Tomoe-gawa), which flows through the Mikawa region of Aichi Prefecture, is known in Japan as a rare “river that branches from one source into two water systems.” This article provides detailed explanations of the Tomoe River in both the Yahagi River water system and the Toyokawa water system, including geographic characteristics, basin information, fishing spots, and environmental conservation activities.
Table of Contents
- Overview and Characteristics of the Tomoe River
- Geography: From Source to Mouth
- Tomoe River in the Yahagi River Water System
- Tomoe River in the Toyokawa Water System
- Municipalities in the Basin
- Major Tributaries and Water System Composition
- Fishing Information for the Tomoe River
- Environmental Conservation and Community Activities
- Tourist Spots and Access
- Related Items
Overview and Characteristics of the Tomoe River
The Tomoe River is a river that originates from Mount Tomoe (elevation 719 meters), located on the border between Shinshiro City and Okazaki City in Aichi Prefecture. Its greatest characteristic is that at the Tsukude Seigaku point in Shinshiro City, it divides into two water systems: the Yahagi River water system and the Toyokawa water system.
Such rivers with dividing water systems are rare nationally and are noted as valuable from a hydrological perspective.
Basic Data for Tomoe River in Yahagi River Water System
- Water System: Class I Water System Yahagi River
- Legal River Length: 56.4 kilometers
- Basin Area: 354 square kilometers
- Source: Mount Tomoe (719m)
- Confluence Point: Merges with the Yahagi River at the border between Hosokawa Town, Okazaki City and Watai Town, Toyota City
Basic Data for Tomoe River in Toyokawa Water System
- Water System: Class I Water System Toyokawa
- Source: Mount Tomoe (719m)
- Characteristic: Connects with the Tomoe River of the Yahagi River water system within Shinshiro City
Geography: From Source to Mouth
Characteristics of the Source Region
The source of the Tomoe River originates from the mountainside of Mount Tomoe, located on the border between Shinshiro City and Okazaki City in Aichi Prefecture. The area around Mount Tomoe, at an elevation of 719 meters, is covered with rich forests and serves as a water source that produces clear water.
The source region is steep mountainous terrain, retaining distinctive characteristics of a mountain stream. This area is also known as a mecca for stream fishing, with amago and rainbow trout and other stream fish inhabiting it.
Division Point: Tsukude Seigaku
The Tsukude Seigaku point in Shinshiro City is the most characteristic location of the Tomoe River. Here the river divides into two branches, one flowing westward as part of the Yahagi River water system and the other flowing eastward as part of the Toyokawa water system.
This water divide forms part of the central water divide and serves as an important geographic point connecting two different water systems that flow into the Pacific Ocean.
Middle Reaches Landscape
The Tomoe River in the Yahagi River water system flows from Shinshiro City through the Asuke district of Toyota City to Okazaki City. Particularly in the Asuke district of Toyota City, it flows through Koarakei (Koarakei Gorge), a representative autumn foliage spot in Aichi Prefecture, forming a spectacular gorge landscape.
In the middle reaches, the river widens and the current becomes relatively calm. This section is known as a prime spot for sweetfish fishing and attracts many anglers.
Lower Reaches and Confluence Point
The Tomoe River in the Yahagi River water system merges with the main stream Yahagi River near the border between Hosokawa Town, Okazaki City and Watai Town, Toyota City. The area near the confluence is characterized by a wide riverbed and calm flow.
Tomoe River in the Yahagi River Water System
The Tomoe River in the Yahagi River water system, with a legal river length of 56.4 kilometers, is one of the major tributaries of the Yahagi River and plays an important role.
Characteristics of the Flow
Originating from Mount Tomoe and flowing westward from the Tsukude district of Shinshiro City through the Asuke district of Toyota City to Okazaki City, the basin varies from mountainous to flat areas, presenting different characteristics in each region.
Water Quality and Environment
The Tomoe River in the Yahagi River water system maintains relatively good water quality. In the upper reaches, it has the characteristics of a clear stream and has received high ratings in environmental ministry water quality surveys.
Rich nature remains in the basin, forming a diverse ecosystem. Broadleaf forests spread along the riverbanks, allowing visitors to enjoy the landscape of each season.
Tomoe River in the Toyokawa Water System
The Tomoe River in the Toyokawa water system has a shorter flow path compared to the Yahagi River water system but functions as an important river in Shinshiro City.
Characteristics of the Basin
Originating from Mount Tomoe and flowing eastward, it merges with the Toyokawa. It has a unique geographic characteristic of connecting with the Tomoe River of the Yahagi River water system within Shinshiro City.
Role of the Water System
The Tomoe River in the Toyokawa water system plays an important role as a water resource for Shinshiro City. It serves as a source for irrigation water and domestic water supply, supporting the life of the region.
Municipalities in the Basin
The basin of the Tomoe River includes multiple municipalities, each working on river management and environmental conservation.
Shinshiro City
- Location: Source region and water divide point
- Characteristics: The only municipality possessing the source of the Tomoe River and containing Tomoe Rivers of both water systems
- Initiatives: Conservation of water source forests, management of stream fishing grounds
Toyota City
- Location: Middle reaches, particularly the Asuke district
- Characteristics: Strong aspect as a tourism resource flowing through Koarakei
- Initiatives: River environment conservation, tourism promotion, disaster prevention measures
- Jurisdiction: River management is handled by the Toyota City Hall Regional Revitalization and Disaster Prevention Division
Okazaki City
- Location: Lower reaches and Yahagi River confluence point
- Characteristics: Flows through flatlands, with widespread use as irrigation water
- Initiatives: Flood control measures, water quality conservation
Major Tributaries and Water System Composition
Multiple tributaries merge into the Tomoe River, forming a rich water system.
Asuke River (Asuke-gawa)
One of the major tributaries flowing through the Asuke district of Toyota City. It merges with the Tomoe River near Koarakei Gorge, forming spectacular valley scenery. It is included in the jurisdiction of the Tomoe River Fisheries Cooperative.
Kamikoshi River (Kamikoshi-gawa)
Another important tributary flowing through the Asuke district. As a river under the jurisdiction of the Tomoe River Fisheries Cooperative, it is also known as a fishing spot.
Other Tributaries
Various large and small tributaries merge into the Tomoe River. These tributaries enrich the water resources of the basin and support a diverse ecosystem.
Fishing Information for the Tomoe River
The Tomoe River is known as one of the finest fishing spots in Aichi Prefecture and attracts many fishing enthusiasts.
Tomoe River Fisheries Cooperative
The Tomoe River Fisheries Cooperative (Tomoe River Fisheries Coop), which manages the Tomoe River and surrounding rivers flowing through Koarakei in Toyota City (former Asuke Town), oversees the management of fishing grounds.
- Managed Rivers: Tomoe River, Asuke River, Kamikoshi River
- Business Content: Management of sweetfish fishing grounds, cultivation of stream fish (amago) business
- Fishing Permits: Daily and yearly permits are sold
- Access: Official homepage provides fishing ground guides and sales outlet information
Fish Species That Can Be Caught
The following fish species can be caught in the Tomoe River:
Stream Fish
- Amago: Lives in clear streams in upper reaches
- Rainbow Trout: Popular as stocked fish
- Char: Lives in limited locations in the source region
River Fish
- Sweetfish (Ayu): Representative fish species of the Tomoe River. Famous for friendship fishing
- Pale Chub: Abundant in middle reaches
- Dace: Widely distributed throughout the basin
- Carp: Lives in quiet areas of lower reaches
- Crucian Carp: Lives in lower reaches
- Eel: Target species for night fishing
Fishing Season
- Stream Fishing: March to September (pay attention to closed seasons)
- Sweetfish Fishing: June to October (opening date determined by the fisheries cooperative)
- Carp and Crucian Carp Fishing: Often available year-round
Fishing Permit Fees
To fish in the Tomoe River, a fishing permit issued by the Tomoe River Fisheries Cooperative must be purchased. In recent years, the FISHPASS (Fish Pass) digital fishing permit service has also become available, allowing easy smartphone-based permit purchases.
Fishing Spots
- Upper Reaches (Shinshiro City): Prime stream fishing spots. Amago and rainbow trout can be targeted
- Middle Reaches (Asuke District, Toyota City): Mecca for sweetfish fishing. Can enjoy scenery around Koarakei
- Kuguひらcho Area: Good accessibility, recommended for beginners
- Lower Reaches (Okazaki City): Carp and crucian carp fishing can be enjoyed
Environmental Conservation and Community Activities
Tomoe River Environmental Conservation Society
The Tomoe River Environmental Conservation Society is a community organization working on environmental conservation of the Tomoe River. It carries out initiatives that are noteworthy among river environmental conservation activities across the country.
Main Activities
- River cleanup activities
- Water quality surveys
- Ecosystem conservation activities
- Implementation of environmental education programs
- Awareness activities for local residents
Water Source Conservation and Forest Preservation
In the source region of the Tomoe River, activities are carried out to conserve water source forests. Forests serve as an important role as a “green reservoir,” storing rainwater and gradually supplying it to rivers.
Disaster Prevention Measures
Toyota City implements disaster prevention measures for the Tomoe River, including installation of river live cameras and creation of flood hazard maps. Particularly around Kuguひらcho, the Toyota City Hall Regional Revitalization and Disaster Prevention Division takes the lead in establishing a disaster prevention system.
Tourist Spots and Access
Koarakei (Koarakei Gorge)
Koarakei, where the Tomoe River flows, is a representative autumn foliage spot in Aichi Prefecture.
- Location: Asuke Town, Toyota City
- Best Season: Mid to late November
- Characteristics: Approximately 4,000 Japanese maple trees color the gorge
- Access: About 1 hour 30 minutes by Meitetsu bus from Meitetsu Nagoya Station
Access to Fishing Grounds
You can access fishing grounds on the Tomoe River using the following methods:
Public Transportation
- Meitetsu Bus: Meitetsu bus from Toyota City Station heading toward Asuke, get off at “Naka” bus stop, about 1 minute walk to Tomoe River
- Toyo Railway Bus: From Shinshiro City toward Tsukude can access the source region
Private Vehicle
- Tomei Expressway: About 30 minutes from Toyota IC via Route 153 toward Asuke
- Shin-Tomei Expressway: About 20 minutes from Shinshiro IC toward source region via prefectural roads
Nearby Tourist Facilities
- Asuke Town Area: Historic townscape retaining the atmosphere of an Edo-period post town
- Sanshuu Asuke-ya Shikirei: Experience facility recreating traditional farm life
- Tsukude Highland: Highland area at approximately 600 meters elevation. Cool in summer, ideal for camping and hiking
River Management and Future Issues
River Management System
The Tomoe River, as a Class I river, is managed by the Ministry of Land, Infrastructure, Transport and Tourism and Aichi Prefecture. Day-to-day management is handled by municipalities in the basin (Shinshiro City, Toyota City, and Okazaki City).
Water Quality Conservation Efforts
Municipalities in the basin conduct regular water quality surveys and work to maintain and improve water quality. They take multifaceted approaches including domestic wastewater measures and factory wastewater monitoring to protect clear streams.
Future Challenges
- Adaptation to Climate Change: Strengthening flood control measures in preparation for increased heavy rain disaster risk
- Ecosystem Conservation: Invasive species countermeasures and protection of native species
- Sustainable Fisheries: Resource management of sweetfish, amago, and other fish
- Balancing Tourism and Environmental Conservation: Reducing environmental impact at tourist sites such as Koarakei
Conclusion
The Tomoe River (Aichi Prefecture) is a nationally rare river that divides from a single source into two water systems: the Yahagi River water system and the Toyokawa water system. With a legal river length of 56.4 kilometers and a basin area of 354 square kilometers, the Tomoe River in the Yahagi River water system flows through Shinshiro City, Toyota City, and Okazaki City, serving as an important water resource for the region.
A beautiful gorge flowing through Koarakei, clear streams bustling with sweetfish and amago fishing, and environmental conservation activities by local residents—the Tomoe River is a river with diverse values of nature, culture, and recreation that should continue to be carefully protected going forward.
Sustainable fisheries management by the Tomoe River Fisheries Cooperative, environmental conservation activities by the Tomoe River Environmental Conservation Society, and disaster prevention measures by municipalities in the basin—through the efforts of many people, the rich natural environment of the Tomoe River is being maintained.
Related Items
- Yahagi River: The main stream where the Tomoe River merges
- Toyokawa: The other Class I river where the Tomoe River merges
- Koarakei: A premier autumn foliage spot in Aichi Prefecture where the Tomoe River flows
- Shinshiro City: A municipality possessing the source and water divide of the Tomoe River
- Toyota City: A municipality managing the middle reaches of the Tomoe River
- Okazaki City: A municipality with the lower reaches and Yahagi River confluence point of the Tomoe River
- Tomoe River Fisheries Cooperative: An organization managing fishing rights of the Tomoe River
- Tomoe River Environmental Conservation Society: A community organization working on river environmental conservation
- Class I River: An important river designated by the state
- Water Divide: Boundary dividing different water systems
- Stream Fishing: Amago and rainbow trout fishing enjoyed in upper reaches
- Friendship Fishing: Traditional sweetfish fishing technique popular on the Tomoe River
