Map Showing Mantua Reservoir

(DWR News Release)

Mantua Reservoir is in the first stages of a fresh start after an Oct. 27 rotenone treatment by the Division of Wildlife Resources.

Division biologists believe that Mantua is well-suited for a future that includes better bass and bluegill fishing than in the past, in addition to trophy trout fishing opportunities unique to northern Utah.

Mantua Reservoir is located next to the town of Mantua, in Box Elder County.

The treatment, which will eliminate nearly every fish in Mantua, is the first step to rebuilding high quality angling opportunities. Prior to the treatment Utah chubs, a prolific forage species, overwhelmed the reservoir. The chubs accounted for about 98 percent, by weight, of its entire fish population.

Kent Sorenson, Division project leader for the treatment, says the Utah chub were attaining lengths more than 12 inches long, making them invulnerable to predation. The chubs were also hiding in Mantua's thick weed bed, helping them escape predation.

The only way to control the chubs and restore a balance to the system is to start over, Sorenson said. He says that by eliminating the chubs, which tied up so much of Mantua's available resources, biologists may now create an improved bass and trout fishery.

It will take biologists weeks though, or even months, to determine how well the treatment worked.

Fathead minnows will be Mantua's new forage fish after the reservoir is restocked. Fathead minnows are smaller than Utah chub and are available to bass and trout as forage throughout their life cycle.

The rotenone used to treat Mantua should naturally oxidize in about six weeks, depending on the temperature. Once the rotenone has oxidized, catchable trout will be reintroduced.

Largemouth bass collected by anglers before the treatment also will be placed back into Mantua, along with bass from other sources. Within a few years biologists expect that the bass fishing will be even better than before the treatment.

Mantua Reservoir will open to fishing in June 1999. At that time catchable trout will swim in the open water, and bass and bluegill will be available throughout the reservoir.

For more information contact the Division's Northern Region office at (801) 476-2740.