Ekawa Yusui Spring Source, Tokushima Prefecture | Thorough Explanation of the Mystery of Abnormal Water Temperature and the Appeal of One of Japan’s Top 100 Waters
The Ekawa Yusui Spring Source located in Kamoshima Town, Yoshinogawa City, Tokushima Prefecture, is a representative spring water spot in Shikoku, selected as one of Japan’s Top 100 Waters. Known for the “abnormal water temperature phenomenon” where the water is cold at around 10°C in summer and warm at around 20°C in winter, it was designated as a natural monument of Tokushima Prefecture in 1954 (Showa 29). This mysterious water temperature fluctuation remains incompletely explained even by modern science, and continues to fascinate many people as a scientifically noteworthy natural phenomenon drawing academic attention.
This article will thoroughly convey the charm of this famous water spot representing Tokushima Prefecture, from basic information about the Ekawa Yusui Spring Source and the mystery of the abnormal water temperature phenomenon, to access methods, nearby tourist spots, and actual visitation experiences.
What is Ekawa Yusui Spring Source? | Basic Information and History
Overview of Ekawa Yusui Spring Source
The Ekawa Yusui Spring Source is clear spring water that springs forth from beneath the Yoshinogawa embankment in Yoshinogawa City (formerly Kamoshima Town, Asage County). The Ekawa River, which has this spring water as its source, flows for approximately 9km from the spring source and merges with the main Yoshinogawa River downstream. It boasts abundant water throughout the year and is cherished as a place of relaxation for local residents.
Location: Tokushima Prefecture, Yoshinogawa City, Kamoshima Town, Chieshima
Designation: Natural Monument of Tokushima Prefecture (Designated August 6, 1954)
Selection: Ministry of the Environment-selected Japan’s Top 100 Waters (Selected 1985)
Water System: Tributary of the Yoshinogawa River system
Nearest Station: Approximately 5-minute walk from Nishi-Asage Station on the JR Tokushima Line
Background of Selection as One of Japan’s Top 100 Waters
In 1985 (Showa 60), the Ministry of the Environment (Environmental Agency at the time) selected “Japan’s Top 100 Waters” for the purpose of preserving excellent water environments nationwide. The Ekawa spring water was selected as a representative water of the Shikoku region, evaluated for its good water quality and the unique abnormal water temperature phenomenon. The clear water quality is suitable for drinking, and visitors not only from the local area but also from distant places come to draw water without end.
Historical Background of Ekawa River
In the past, the Ekawa was part of the main flow of the Yoshinogawa River, but was separated from the main flow due to flood control projects and embankment construction. The current spring water is thought to be intricately related to this topographical change and the underground flow of the Yoshinogawa River. In the downstream area of the Ekawa, there is “Ekawa・Kamoshima Park,” known as a cherry blossom viewing spot, and it becomes crowded with flower-viewing visitors in spring.
The Mystery of the Abnormal Water Temperature Phenomenon | Cold in Summer, Warm in Winter
Water Temperature Reversal by Season
The most distinctive feature of Ekawa Yusui Spring Source is the “abnormal water temperature phenomenon” where water temperature changes significantly with the seasons.
- Summer season (July to September): Water temperature around 10°C (large temperature difference from outside temperature exceeding 30°C)
- Winter season (December to February): Water temperature around 20°C (reversal phenomenon from outside temperature around 5°C)
- Spring and autumn: Water temperature transitions in intermediate range
While most spring waters typically maintain nearly constant temperatures year-round, the water temperature at Ekawa Yusui Spring Source changes in a manner opposite to the seasons. Particularly in winter, the temperature difference between water and air sometimes creates a fantastical sight of steam rising.
Scientific Hypotheses about Abnormal Water Temperature
Although not completely elucidated to date, several scientific hypotheses have been proposed.
Hypothesis 1: Long-Distance Groundwater Flow Theory
The theory proposes that water that permeates underground near Shiroyama in Kawashima Town, Yoshinogawa City, flows slowly through underground gravel layers, becoming cooled in summer and warmed in winter before reaching the Ekawa area. The slow groundwater flow causes seasonal temperature changes to appear with a time lag.
Hypothesis 2: Multiple Water Source Mixing Theory
The theory suggests that multiple groundwaters from different depths and distances mixing together creates the unique water temperature pattern. The possibility is pointed out that shallow groundwater and deep groundwater mix in different proportions depending on the season.
Hypothesis 3: Geological Structure Characteristic Theory
The theory proposes that the sedimentary layers of the Yoshinogawa River and the surrounding geological structure form a special heat exchange system, with different heat balance mechanisms working depending on the season.
None of these hypotheses has reached definitive evidence, and this mystery further enhances the mystical nature of Ekawa Yusui Spring Source.
Value as a Natural Monument
The 1954 designation as a Tokushima Prefecture natural monument recognized the academic value of this abnormal water temperature phenomenon. As a natural phenomenon with many scientifically unexplained aspects, it continues to draw attention as a research subject in hydrology and geology.
Access Methods and Parking Information
Access by Public Transportation
Using JR Tokushima Line
- Get off at “Nishi-Asage Station” on the JR Tokushima Line, approximately 5-minute walk
- Approximately 20-30 minutes from Tokushima Station to Nishi-Asage Station
- There are guide signs from the station to the spring source, so you can arrive without getting lost
Nishi-Asage Station is a relatively small station, but access to Ekawa Yusui Spring Source is very convenient. Within a few minutes’ walk from the station, you can see the Yoshinogawa embankment, and the spring source is just beyond.
Access by Automobile
From Tokushima Expressway
- Approximately 15 minutes from “Wakemachi IC” on Tokushima Expressway
- Approximately 20 minutes from “Tossei IC” on Tokushima Expressway
- Accessible via National Route 192
From Tokushima City
- Approximately 30 minutes west on National Route 192
- Prefectural Route 12 via is also available
Parking Information
A dedicated free parking lot has been established at Ekawa Yusui Spring Source.
- Capacity: Approximately 20-30 vehicles
- Fee: Free
- Operating hours: Open 24 hours (though lighting is limited at night)
- Facilities: Rest facility called “Iyashi no Sha” available
In the morning hours, local residents often come to draw water, and the parking lot may become congested. If you want to view leisurely, early morning or afternoon is recommended.
Points of Interest and Ways to Enjoy Ekawa Yusui Spring Source
Best Season for Water Source Observation
Winter season (December to February) is most recommended. The temperature difference between the 20°C water and outside temperature creates a fantastical sight of steam rising. In the early morning when the temperature drops, steam rises from the water surface like a hot spring, creating a mystical atmosphere.
Summer season (July to September) allows you to experience the coldness of 10°C water by immersing your hand. On sweltering hot days, you can experience the coolness like a natural air conditioner.
Drawing Spring Water
Many visitors, not just local residents, draw water at Ekawa Yusui Spring Source.
Points to note when drawing water:
- Bring a clean container
- If drinking, boiling is recommended as a precaution (Japan’s Top 100 Waters designation does not guarantee suitability for drinking)
- Be considerate of local residents’ use and don’t obstruct them
- Observe proper manners to avoid polluting the surrounding environment
Photography Tips
- Early winter morning: Fantastical scenery with rising steam
- Spring: Beautiful contrast between surrounding cherry blossoms and clear stream
- Summer: Beauty of vibrant green and transparent water
- Autumn: Harmony of autumn foliage and clear stream
Due to extremely high water transparency, photographs can be taken showing clearly to the water bottom.
Rest at Iyashi no Sha
Near the parking lot is a rest facility called “Iyashi no Sha.” With a roof-covered structure like a pavilion, it can also serve as a shelter during rain. Benches are installed, allowing you to rest leisurely while gazing at the spring water.
Nearby Tourist Spots and Dining Information
Tourist Spots in Yoshinogawa City
Ekawa・Kamoshima Park
Located downstream from Ekawa Yusui Spring Source, this is a famous cherry blossom viewing spot. In spring, approximately 500 Somei Yoshino cherry trees bloom brilliantly, attracting many flower-viewing visitors. The walking path along the river is perfect for strolling.
Yoshinogawa City Misato Hotaru-kan (Firefly Museum)
This is a firefly observation facility in the Misato district of Yoshinogawa City. Around June, you can see the frenzied dance of Genji fireflies, creating a fantastical sight. It is located approximately 30 minutes by car from Ekawa Yusui Spring Source.
Awa no Dochu (Awa Earth Pillars)
A scenic spot designated as a national natural monument, where soil pillars formed by rainwater erosion stand side by side in a rare landform. Considered one of the world’s three major earth pillar formations, it is approximately 15 minutes by car from Ekawa Yusui Spring Source.
Local Cuisine and Direct Sales Shops
JA Tokushima Himawari Farm Products Market Kamoshima Store
A direct sales shop lined with fresh local vegetables, fruits, and processed goods. You can find Tokushima specialties such as Naruto sweet potatoes, sudachi citrus, and Awa chicken. It is conveniently located approximately 5 minutes by car from Ekawa Yusui Spring Source.
JA Asage-gun Himawari Farm Products Market Kawashima Store
A farm product direct sales shop in Kawashima Town, Yoshinogawa City, with abundant seasonal vegetables and fruits. Recommended for those wanting to enjoy local flavors.
Tokushima Ramen
Various famous Tokushima ramen shops are scattered throughout the Yoshinogawa City area. Be sure to taste the Tokushima style with rich pork bone soy sauce broth topped with a raw egg.
Nearby Accommodations
Healing Inn Dochu Land Shin Onsen
A hot spring inn near Awa no Dochu (Awa Earth Pillars). You can enjoy natural hot spring and cuisine made with local ingredients. It is approximately 15 minutes by car from Ekawa Yusui Spring Source.
HOTEL AZ Tokushima Itano Branch
A business hotel where you can stay at reasonable prices. Access to Tokushima City is also good, making it a convenient base for sightseeing.
Hotels in Tokushima City
There are various types of accommodations in Tokushima City, with approximately 30 minutes by car to Ekawa Yusui Spring Source. City accommodation is one option if combining with Tokushima sightseeing.
Regional Events and Culture
Gokuro Festival
The “Gokuro Festival” is held annually in Yoshinogawa City. This festival honors Gokuro, a righteous person from the Edo period, and is a valuable opportunity to experience the region’s traditional culture. Performances of Awa Dance and food stalls are offered, allowing visitors to feel the vitality of the region.
Cherry Blossom Festival
In spring, the Cherry Blossom Festival is held at Ekawa・Kamoshima Park, with nighttime illumination. The collaboration of spring water and cherry blossoms is magnificent, attracting many tourists.
Notes and Etiquette for Visiting
Cooperation in Environmental Conservation
Ekawa Yusui Spring Source is a precious natural environment. Please note the following:
- Always take your trash with you
- Washing and car washing in the spring water source area are prohibited
- Do not collect aquatic organisms or plants
- Do not disturb the quiet environment with loud voices or noise
Safety Precautions
- The waterside is slippery, so be careful of your footing
- Do not take your eyes off small children
- Even in summer, the water temperature is extremely cold at 10°C, so avoid prolonged water play
- In winter, there is a possibility of road surface freezing
Consideration for Local Residents
Ekawa Yusui Spring Source is also used as a water source for local residents’ daily life. Especially in the early morning hours, many local people come to draw water, so use it in the spirit of mutual courtesy.
Water Quality and Environment of Ekawa Yusui Spring Source
Characteristics of Water Quality
The water at Ekawa Yusui Spring Source boasts clear water quality originating from the Yoshinogawa underground flow.
- Transparency: Extremely high, allowing visibility to the water bottom
- pH: Close to neutral, appropriate range for drinking
- Minerals: Soft water containing appropriate mineral content
- Water volume: Stable spring discharge throughout the year
Aquatic Life and Ecosystem
Due to its clear water quality, the Ekawa River is home to various aquatic organisms. Small fish, aquatic insects, and aquatic plants can be seen, maintaining a rich ecosystem. The cold water temperature in summer, in particular, is a precious habitat for cold-water species.
Ekawa Yusui Spring Source Throughout the Seasons
Spring (March to May)
Cherry blossoms bloom in the surrounding area, and the Cherry Blossom Festival is held at Ekawa・Kamoshima Park. The contrast between fresh green leaves and clear stream is beautiful. Water temperature gradually begins to decrease, and with the arrival of spring, the water becomes colder.
Summer (June to August)
The water temperature drops to around 10°C, and you can experience the exhilaration of touching cold water in the midst of midsummer heat. The surrounding greenery deepens, and the cool atmosphere of the clear stream stands out. You can also see local children enjoying water play.
Autumn (September to November)
Surrounding trees begin to change color, and a beautiful landscape of autumn foliage and clear stream spreads. Water temperature gradually begins to rise, and you can feel the seasonal change through water temperature.
Winter (December to February)
The most fantastical season. Due to the temperature difference between the 20°C water and outside air, a mysterious sight of steam rising from the water surface can be seen. Early morning when temperatures are coldest is especially recommended.
Planning Your Visit to Ekawa Yusui Spring Source
Recommended Staying Time
Viewing the Ekawa Yusui Spring Source itself takes approximately 30 minutes to 1 hour, but including surrounding walks, photography, and water drawing, a 1-2 hour stay is recommended.
Model Courses
Half-Day Course
9:00 AM Arrival and viewing of Ekawa Yusui Spring Source
10:00 AM Stroll through Ekawa・Kamoshima Park
11:30 AM Shopping and lunch at Himawari Farm Products Market
1:00 PM Viewing Awa no Dochu (Awa Earth Pillars)
Full-Day Course
9:00 AM Arrival and viewing of Ekawa Yusui Spring Source
10:30 AM Yoshinogawa City Misato Hotaru-kan (seasonal)
12:00 PM Lunch at a local restaurant
2:00 PM Viewing Awa no Dochu (Awa Earth Pillars)
4:00 PM Bathing and rest at Dochu Land Shin Onsen
Useful Items to Bring
- Clean container for drawing water (such as plastic bottle)
- Camera (especially if you want to photograph winter steam)
- Towel (after touching water)
- Winter clothing (if visiting in winter)
- Comfortable walking shoes (waterside is slippery)
Conclusion | Tokushima’s Mysterious Famous Spring Water
Ekawa Yusui Spring Source is a representative spring water spot in Shikoku, possessing the scientific mystery of abnormal water temperature, the good water quality selected as one of Japan’s Top 100 Waters, and the value as a Tokushima Prefecture natural monument.
Convenient conditions are in place: a 5-minute walk from JR Nishi-Asage Station, free parking lot, and easy combination with nearby tourist spots. With different charms in each season—coldness in summer and warmth in winter—it is a spot where you can make new discoveries with every visit.
When visiting Tokushima Prefecture, please be sure to visit this mysterious spring water source. By experiencing the inexplicable wonder of nature and the beauty of clear water that cannot be explained by science, you will surely have a special experience that cannot be tasted in daily life. Why not verify the charm of the spring water that has been loved by local people for many years with all five of your senses?
