Hiyoshi Co., Ltd. Launches "Aoko Monitoring System" Service (Patent Pending)

Hiyoshi Co., Ltd. (Headquarters: Omihachiman City, Shiga Prefecture) has devised the "Aoko Monitoring System" that regularly grasps the occurrence status of Aoko (blue-green algae) through multivariate analysis of high-resolution satellite images of the lake surface, based on knowledge cultivated through water quality improvement in Lake Nishi-no-ko, an inland lake in the eastern part of Lake Biwa, Shiga Prefecture. We have started providing services for this system and are jointly filing a patent application with our development partner, blue and tech Inc. (Headquarters: Kyoto City, Representative Director: Manabu Watanabe).

If you are interested in water quality evaluation and Aoko monitoring of lakes and dams using high-resolution satellite imagery, please contact us.

■ Realizing the "Visualization" of Aoko

Aoko refers to the phenomenon and accumulation of phytoplankton (blue-green algae) in the water that dyes the water surface green. With rising temperatures due to climate change, the risk of its occurrence is predicted to increase in lakes and reservoirs.

However, with conventional surveys, it is not easy to grasp the entire vast lake in terms of "when, where, and to what extent" it is occurring.

Therefore, our company has devised a method for the "Aoko Monitoring System" that regularly grasps the lake surface conditions (Aoko occurrence status and Aoko level) by using remote sensing technology that analyzes high-resolution satellite images (allowing confirmation of satellite imagery, local camera, weather data, and water quality sensor data on a single screen).

This helps in estimating the Aoko occurrence status and Aoko level, and in understanding and improving water quality conditions.

■ Delivering "Aoko Maps" Every 5 Days

Our "Aoko Monitoring System" utilizes satellite remote sensing technology to create Aoko Maps (estimating Aoko occurrence status and Aoko level and displaying them on a map) every five days. Observation data (weather meters, continuous water quality meters) and camera images allow for checking the latest conditions.

*Satellite observation may not be possible depending on climatic conditions such as cloud cover.

Creation of Aoko Map (Visualizing Aoko occurrence areas and Aoko levels on a map)

Image of Aoko level estimation in Lake Nishi-no-ko, Shiga Prefecture

Real-time confirmation possible with weather meters, continuous water quality meters, and camera footage

Aoko Level Image Judgment (AI is used to automatically determine the Aoko occurrence level from images taken by cameras)

Image of Aoko in Lake Nishi-no-ko, Shiga Prefecture, taken in 2025

Inquiry of Inspection Results (Linkage with our proprietary tool "Anarepo®" for managing analysis results allows confirmation of measurement data when water quality tests are conducted at measurement points)

Proprietary Tool "Anarepo®": Analysis Result Inquiry Page

*¹ Aoko (blue-green algae): A type of phytoplankton also known as cyanobacteria. When it proliferates in large numbers, it causes the water surface to turn green, producing toxins (cyanotoxins), causing odor problems, and depleting dissolved oxygen, which has significant impacts on water supply, fisheries, and ecosystems.

Hiyoshi Co., Ltd. General Affairs Department, Corporate Planning Division, Contact: Tomo Nishimura

Company Name: Hiyoshi Co., Ltd.
Representative: Masashi Suzuki, President and Representative Director
Address: 908 Kitano-sho, Omihachiman City, Shiga Prefecture, 523-8555
Established: December 23, 1958
Business Activities: Environmental and food analysis, infrastructure maintenance and management, industrial chemical sales, environmental conservation business
Capital: 20 million yen
URL: https://www.hiyoshi-es.co.jp/
E-Mail: koho@hiyoshi-es.co.jp
Tel: 0748-32-5111
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