Koga Airfield

The airfield was closed because the Japanese Ministry of Land, Infrastructure, Transport and Tourism (MLIT), which manages the land, did not renew the land use permit for the operating gliding club. The airfield was located within the Watarase Retarding Basin (Watarase Yūsuichi), a critical flood control area. The government's decision prioritized the land's primary function for water management and nature conservation over its secondary use for aviation.

The site of the former airfield has been completely decommissioned and returned to its natural state. All aviation infrastructure, including the unpaved runway, markings, and support buildings, has been removed. The land is now an integral part of the Watarase Yūsuichi, a nationally managed flood control basin and a designated Ramsar Convention wetland of international importance. The area is a nature reserve and is used for public recreation like cycling, walking, and birdwatching, with no remaining trace of its aviation past.

Koga Airfield, more commonly known as the Watarase Glider Port (渡良瀬グライダー滑空場), was one of Japan's most important and active gliding centers. For many years, it was operated by the Japan Gliding Club (日本グライダークラブ) and served as a major hub for recreational gliding, pilot training, and national gliding competitions. Its location within the vast, flat, and open Watarase Retarding Basin provided ideal and safe conditions for unpowered flight. Operations primarily consisted of launching gliders using tow planes (such as Piper PA-25 Pawnees).

There are no known plans or prospects for reopening Koga Airfield. The land's official designation as a critical flood control basin and a protected wetland by the national government makes the re-establishment of an airport highly improbable. The decision to close the airfield was final, and the gliding community that once used the site has since relocated its main operations to other airfields, such as Itakura Glider Port in nearby Gunma Prefecture.