Yellowstone National Park Superintendent Suzanne Lewis announced today that due to high water temperatures, effective Tuesday, July 22, the Madison, Firehole, and Gibbon Rivers (up to Gibbon Falls) and their tributaries will be temporarily closed to fishing until further notice.

Water temperatures in these rivers are unusually high due to the combination of thermal runoff and the unprecedented warm temperatures in the region. Temperatures in the Firehole River, as measured by the USGS Firehole gauging station, have been above 79° F since July 10. Temperatures at the Gibbon gauging station have been above 73 ° F almost every day since July 10. Water temperatures of 77 ° F can be lethal to trout. In addition, as water temperatures rise, incidental-hooking mortality increases further affecting fish populations.

While the current temperatures are unusually high, fish that live in these rivers have adapted to living at higher than normal temperatures. A study conducted on the Firehole River, which historically has high summer temperatures due to hot water runoff from thermal features, found that rainbow and brown trout migrated to tributaries or colder areas of the river when temperatures increased above 75° F. On several occasions, tagged fish migrated through warmer portions of the stream to reach cooler areas. These rivers will remain closed to fishing until the daily maximum temperatures decrease to below 73° F (22.7 degrees C) for 3 consecutive days and the seven-day weather forecast predicts lower maximum daily temperatures. By clicking on these links, you can access the Firehole River Gauging Station, or the Gibbon River Gauging Station info (which is the temperature gauge for both the Gibbon and Madison rivers). Click here to see the Seven-day Weather Forecast.

Superintendent Lewis reminds anglers that the only rivers closed to fishing inside the park are the Madison, Firehole, and Gibbon (up to Gibbon Falls) and their tributaries. All other park waters normally open to fishing remain open to fishing at this time.