Exelon Nuke Plant Producing Walleyes and More

Just off Illinois Route 84, three miles north of Cordova, about 30 minutes north of the Quad Cities, 150 to 250 thousand fingerling walleyes are produced annually from the hatchery at the Exelon Nuclear Generating Station there. This is the only fish hatchery operated by a nuclear power plant in the United States.

Their cooling water canal didn’t perform as anticipated, so a new discharge system was designed and put into operation in 1983. The potential to utilize the original canal as a fish hatchery was pushed by the Iowa and Illinois DNRs and The Isaak Walton League. Through negotiations with these groups spearheaded by Jim Mayhew of Iowa, it became a reality in the early ‘80s, and since then has produced many millions of walleyes for the Mississippi and Rock Rivers and tributaries, as well as advanced fingerlings recently planted in the new lake at Lost Grove.

Over the years, the 50-plus-acre old canal has proved a perfect hatchery system for river walleyes. Very early each spring, employees capture about four dozen male and female walleyes from that stretch of the river and hold them. When the females are ready to spawn, the eggs are collected, the males are milked of sperm and the eggs are fertilized. The walleyes, both male and female, are returned to the river.

The hatch rate is usually better than 80 percent under these controlled conditions, which yields approximately five to six million eggs, producing about four to five million fry. When the fry are a few days old they are released from the tanks into the canal, where they are allowed to grow to 2 to 2 ½ inches long. This takes approximately two months in water that is 70 to 80 degrees. About a third will be marked along the side using a metal bar super-cooled by liquid nitrogen. This does not harm the fish, but allows Exelon, through angler reporting and fall electrofishing assessments, to keep track of their walleyes.

The goal is to release at least 125,000 fingerlings into Pool 14 and 50,000 into pool 13. Some years they fall short, but many years the releases are far in excess of the stated goal. All fry not released into the pools of the Mississippi are given to the Illinois or Iowa DNR or other agencies to plant in waters in these two states. Studies have shown that to date, about one third of all walleyes in Pool 14 come from this operation.

In addition to the hatchery operation, Exelon maintains a long-term monitoring system to document the river and its fishery around the plant. Every summer, twice a month from June to September, eight sites are electro-shocked and precise records are kept and used for comparison purposes to determine the health of those waters.

Using a 1,000-foot net, 20 feet tall with 1-1/2-inch mesh, four locations are seined four times in October and November each year. Every fish over 7 to 8 inches in length, in 3 1/2 acres of water, is captured and indexed for future reference and comparison. During nettings, they have collected not only the usual pool 14 river fish, but less common species like paddlefish and Asian carp, as well as walleyes in the 10- to 13-pound range.

In another Mississippi River operation, each spring they tag three thousand or more fresh water drum to monitor their health. Since these fish reproduce through free-floating eggs, they are more likely to be impacted by the plant than other species. While the tagging helps with their monitoring of the area drum, they also welcome calls from fishermen who catch these tagged fish to increase their data.

Additionally, the Cordova hatchery system purchases hybrid striped bass fingerlings less than an inch long. They are held and fed until they are at least six inches long and then released into the Mississippi from pools 14 to 17. While they purchase somewhere around 10,000 hybrids a year, these popular fish do tend to wander. They have been caught as far away as Des Moines, Iowa and in the Illinois River south of Peoria.

As a part of their aquatic river monitoring, once each week they collect a 24-hour sample of anything and everything that collects on fine mesh screen on the water intake pipe. Over a year, they will find dozens of species of aquatic life.

According to Exelon’s Aquatic Biologist, Jeremiah Haas, some new programs are also proving successful. They recently joined the efforts of the Illinois DNR to restore the alligator gar to Illinois waters through a hatchery initiative, and to stock endangered mussels like those displaced by the new I-74 Bridge.

This is a long-term project, since mussels can’t be planted until they are at least two years old. Recently, the Exelon program planted 530 Yellow Sand Shells and 327 Black Sand Shells in the Iowa River. These numbers may not seem impressive, but for endangered mussels, they are significant. The plants were made in tributaries where they have a better chance of expanding into larger, viable colonies than in recreational or commercial rivers.

For any of you fishermen that like to golf at TCP Deere Run, take a look in the lake between the 4th and 5th holes, and you might catch a glimpse of the gold from Exelon’s endangered mussels planted there last year.

Less than a decade ago there was a concerted effort to close the Exelon Nuclear Plant at Cordova. Due to legislation passed within the past couple of years, the plant is now assured of operation into the next decade. Their interest in conservation, providing the personnel, a fish hatchery and a number of important aquatic facilities and programs, has made them not only a good neighbor, but a local asset. Exelon is only one of many companies that work with various state agencies and conservation groups to bring about a healthier outdoors.

This is the time of year to catch a bunch of nuclear walleyes!