White Clay dams to be removed
12:29 AM, Sep. 21, 2011
It’s been centuries since American shad, their relatives the hickory shad and even striped bass swam up the White Clay Creek to fresh, nontidal areas to spawn.
But if all goes well, that could change when the white flowers of the shadblow trees burst into bloom.
The early spring flowers historically signaled the annual shad run – marked by the metallic flashes on the water of fish heading upstream.
The Water Resources Agency, part of the University of Delaware’s Institute for Public Administration, received a $42,000 grant from the FishAmerica Foundation as part of a project to remove a section of the first of seven dams that block fish passage along the creek.
The agency’s timeline is to have the dam out this winter so shad and other migrating fish can make their spring spawn a little farther upstream than they’ve gone in the past.
The agency has a five-year plan to remove all seven dams along the White Clay Creek in Delaware. The goal: to restore migratory fish at least into the White Clay Creek State Park and the National Wild and Scenic White Clay Creek Preserve, said Gerald Kauffman, director of the water resources agency.
“Shad can’t jump,” he said. And that means these fish “can’t use traditional fish ladders.”
The first step, expected to begin in November, is to remove a section of Dam 1 along White Clay Creek near Delaware Park, at Stanton.
Here, the clear water ripples over mica-fleck sediment and rocks and tumbles over a wooden dam built in the 18th century. The water from the creek drops more than 70 feet to just above sea level in its journey from the Paper Mill dam to Stanton.
“That’s why they built the mills there,” Kauffman said. That water moving downhill provided the power needed to fuel an early colonial economy and get the grain to a sea level port, where it could be transported to the Christina River, the Delaware and beyond.
Dam 1, an 8- to 9-foot-tall structure, was originally built to divert water into a mile-long millrace.
The plan, Kauffman said, is to preserve a section of the original, historic dam while removing most of it to allow for the passage of fish.
That will give migratory fish an additional four miles to travel before they are stopped by the Red Mill dam. The Red Mill dam has its roots in early Colonial history, too. An original dam was built in 1727 for a grist mill and was part of a 600-acre tract that included the John England Manor. Beyond that, there is the Karpinski Park Dam, the Paper Mill Dam (with historic roots to the Simonton’s Mill built in 1702), the Newark Intake Dam, the Creek Mill Dam and the Deerfield Dam.
Creek is success story
While water still backs up and spills over the Stanton dam, it no longer flows into the millrace, and the dam doesn’t serve as a water-control structure. In fact, during Hurricane Irene and the remnants from Tropical Storm Lee, so much water flowed that it topped the dam and flooded the areas along the stream bank.
Doug Janiec, a stream ecologist with Duffield Associates, came up with the dam removal plan.
The dam was constructed by building a wooden crib-like structure that was filled in. Over the years, it was repaired and in some sections concrete was placed over the top.
Over the course of more than 200 years, water periodically topped the dam. The overflowing water created a smaller route – a new oxbow that cuts close to the White Clay Creek Golf Course.
“Taking this dam out is going to resolve a lot of that,” Janiec said.
As part of the restoration, the oxbow will be removed and the shoreline repaired, he said.
He did modeling to make sure the project wouldn’t significantly alter water flow and creek habitat upstream and downstream.
The dam removal work is expected to take about two days, Janiec said.
Kauffman said the White Clay is one of Delaware’s success stories when it comes to water quality improvements. “I’d give it a B-plus,” he said. “It’s above average.”
Zinc, which was once a problem in the creek system, has mostly flushed out, he said. And oxygen levels in the water range from 6 to 8 parts per million, he said. The state standard for a fishable river is 4 parts per million.
“It’s sort of like a bellwether,” of environmental quality, he said.
State environmental officials did a fish abundance study in May 2010 during the spring spawn, just above and below the dam. They counted 21 hickory shad in the pool just above the Stanton Dam and 338 just below it. There were also striped bass, said Matt Fisher, a state fisheries biologist who worked on the study. Upstream of the dam, they didn’t catch shad or striped bass, he said.
“The dam was truly a blockage,” Fisher said.
As part of the restoration effort, the Water Resources Agency is running a shad-to-schools program. They get shad eggs from a hatchery in Easton, Pa., and school classes hatch them and raise them to fry size. They are released downstream of the Stanton Dam.
The idea is to get hatchlings with the genetic imprint of the Delaware estuary, he said.
Eventually, he said, they would like to work with a partner to get a fish hatchery in northern Delaware. The state Division of Fish & Wildlife operates a shad hatchery along the Nanticoke River near Seaford. But these fish would be genetically different than fish in the Delaware River system.
Kauffman said that in Colonial times, landowners didn’t recognize that small dams would have an impact on fish spawning.
Laws were later enacted to limit dam construction.
This project, Kauffman said, “is really the intersection of history and environmental restoration.”
“The water quality here is probably as good as it’s been since the Industrial Revolution,” Kauffman said. “If the fish can come back. That’s good for drinking water.”