Sequoia and Kings Canyon National Parks Set to Work on EIS for Yellow-Legged Frog Recovery

Officials in Sequoia and Kings Canyon national parks want to move ahead with ridding non-native trout from roughly 85 lakes and ponds in their parks to help recover populations of native mountain yellow-legged frogs. USGS photo.

Not too long ago fisheries experts in the High Sierra realized that if they removed non-native trout from high-elevation lakes, they could boost fragile populations of a small frog that once was widespread throughout the range. Now Sequoia and Kings Canyon national parks want to remove trout from slightly more than 80 of the parks' 560 lakes and ponds to give the mountain yellow-legged frog a chance for survival.

This diminutive amphibian was once one of the most abundant vertebrates in the Sierra Nevada. The flash of its yellow legs could be seen and the echo of its croaking could be heard across the Sierra’s alpine lakes, even those nestled at 12,000 feet that contain watery habitats typically too cold for amphibians. Unfortunately, that empire began to crumble as long ago as 1850 when non-native trout were first transplanted into some of those lakes to increase fishing opportunities. The introduced fish found the frogs and their offspring to be delectable. Fish stocking became more vigorous in the 1920s when the State of California took control of the program; in the 1950s the program was stepped up again as ground crews transplanting trout received aerial support for stocking some of the high backcountry lakes.

One of the reasons we know so much about the historic distribution of the mountain yellow-legged frog and its habitat needs was one of the most ambitious scientific explorations ever conducted, the Grinnell Survey. Launched in 1908 and led by field biologist and zoologist Joseph Grinnell, it cruised through a wide swath of California, including a good chunk of Yosemite National Park, in an audacious bid to document the state’s natural systems.

Today it’s thought that the frogs inhabit less than 10 percent of their historical distribution, in part because of the trout stocking. But the frog’s future outlook has improved of late. In Yosemite and Sequoia national parks ecologists have been working in recent years to remove trout from dozens of lakes, and the amphibians are rapidly rebounding. In some instances, lakes that held fewer than 200 frogs in 2001 saw populations explode to 14,000 tadpoles and 3,600 adults three years later after most of the trout were removed.

With such success, the two parks want to remove non-native fish from up to 84 of their lakes and ponds. The other day they posted a notice in the Federal Register of their intent to prepare an environmental impact statement to examine the consequences of such an action. According to a release from the parks, "this project is needed to preserve and restore aquatic ecosystems and populations of native species, including mountain yellow-legged frogs in high elevation lakes and streams, creating new opportunities for visitors to experience native wildlife yet also maintaining recreational fishing opportunities."

Here is a little more background on why the parks decided an EIS, and not a less-intensive environmental assessment, was needed before they could move ahead with the project:

Initially public scoping was conducted in early 2007, and it was anticipated an environmental assessment (EA) would be prepared to analyze the project. During that time, the parks received comments from over 30 different sources. As staff began the environmental analysis and re-examined information provided by the public, it became clear that the project had the potential for significant impacts on the human environment. There was a level of controversy associated with the proposal, potential for uncertainty and both adverse and beneficial consequences, and unique
and unforeseeable environmental impacts. For these reasons, in early 2009 the Superintendent determined that an EIS would be prepared.

According to the parks, all scoping comments received to date are included in the official administrative record; the Scoping Summary Report includes all comments and information obtained to date and is available on-line at It is not necessary for previous letters to be resubmitted; however if prior respondents have new issues or information they wish to bring forward then new letters should be submitted. The public can submit comments on the project until November 21, 2009, online at: http:/, by email at
, or by writing:

Aquatic Ecosystem Restoration
Sequoia and Kings Canyon National Parks
47050 Generals Highway
Three Rivers, CA 93271