The first fish ladder would run alongside Mill Dam in Mount Holly on the North Branch of Rancocas Creek. The Army Corps' plans also call for fish ladders upstream, at Pemberton Dam in Pemberton Borough and Mirror Lake Dam in Pemberton Township.
The Smithville Dam in Eastampton already has a fish ladder.
To increase fish populations, the ladders would be "very effective, especially in the areas they're targeting, the North Branch of the Rancocas Creek," said Hugh Carberry, the principal biologist in South Jersey for the state Bureau of Freshwater Fisheries.
According to environmental experts, anglers would see more anadromous fish - saltwater species that breed in freshwater - such as alewife and blueback herring and American shad.
Carberry said that American shad are a particular draw for anglers. "They're a pretty hard-fighting fish for their size." Juvenile striped bass and blackjack herring also might be able to pass through the fish ladders on their way to the native breeding waters they lost to power mills when the dams were built more than a century ago. The fishes' populations have declined drastically since construction of the dams, experts say.
In addition, the extra species of fish will benefit other species already swimming upstream of the dams. The sunfish, black crappies, and largemouth and smallmouth bass that are regularly stocked in the creek and lakes probably will feed on the newcomers and become more robust, Carberry said.
A fish ladder is a submerged aluminum chute with baffles in regular intervals that create eddies to slow the velocity of rushing water. In theory, fish can swim upstream through the chute.
A similar fish ladder installed by the Bureau of Freshwater Fisheries on the Maurice River in Cumberland County has helped restore alewife herring to Union Lake, Carberry said.
The North Branch of the Rancocas and the series of man-made lakes above it in Pemberton Township are considered the best fishing waters in Burlington County, despite being blocked from the Delaware River by four dams.
The lakes are also recovering from being dredged earlier this decade to rebuild the Mirror Lake Dam.
For Mount Holly, the ante for the ladder proposal is $7,500, or about 5 percent of the projected $150,000 cost of the Mill Dam fish ladder.
The local costs of the two other fish ladders could be more expensive. Installing fish ladders in the Mirror Lake and Pemberton dams could cost as much as $325,000, according to Mark Eberle of the Army Corps of Engineers. Construction could be completed by October 2001, Eberle estimated.
The fish ladder proposal comes at a time when the Mount Holly Township Council has assembled more than half of the various federal and state grants and low-interest loans that it wants to finance $840,000 in upgrades to Mill Dam Park.
The bulk of the money for the park improvements is coming from the state Green Acres Program.
Mount Holly officials said they would explore whether Green Acres would cover their part of the fish ladder cost.