Summer 2004

Groundswell for Groundwater

Protecting land around Stateville Prison may save the critical seeps of Lockport Prairie — and the rare species that depend upon them

By Jill Riddell

Some earthly elements are common: iron, for example, and silicate. Some are so rare as to be considered precious: think rubies, perhaps, or platinum. The same can be said for Illinois landscapes; some were abundant to begin with, and among what little remains of natural land, they are well-represented and reasonably common.

	American goldfinch among wetland grasses in Lockport Prairie. Photo by Gerald D. Tang.

But in Will County, there is the ecosystem equivalent of a ruby, an example of something that was rare in the past, rare today, and will likely be forever rare: the wet dolomite prairie. Produced by specific and unlikely sets of circumstance, this natural community can't be reproduced on a whim. If you were to decide to devote your life to trying to manufacture a wet dolomite prairie, the first thing you would need is a location where 425 million-year-old limestone bedrock lies under the surface. Next you must arrange for a glacier to visit and, in the process of its arrival and departure, to scour out a wide valley, leaving a river in the middle and bluffs along the side. In between the river and the bluffs, there must be a flat river plain. On the plain you can have some soil to support marshes and prairies, but scattered here and there, you must have some spots where the glacier scraped things right down to the limestone bedrock. Otherwise you won't get your dolomite prairie, because that's where it's going to form: on the frighteningly inhospitable, almost-bare dolomite rock.

In the Chicago Wilderness region, the only place where these precise conditions occurred is along the Des Plaines River, from Willow Springs to Joliet. (There are also dolomite prairies slightly farther west, in Byron County near Rockford.) It's impossible to know how much dolomite prairie may have existed in the lower Des Plaines Valley prior to 1972, but when the Illinois Natural Areas Inventory was completed that year, the document stated that there were only 36 acres statewide. Much of this acreage was destroyed by mining at nearby sites. But there is protected dolomite prairie remaining in the 250-acre Lockport Prairie Nature Preserve, a site west of the town of Lockport.

Lockport Prairie is home to certain plants that show decided preference for the spartan conditions of dolomite prairie: tufted hair grass, slender sandwort, and prairie satin grass are a few examples. But the dolomite prairie isn't the only natural community that is of interest at this site. The nature preserve is a complex mix of dry and wet prairies, marshes, graminoid fen, and sedge meadows, some of these fed by groundwater and by seeps in the bluffs on the western edge of the river valley. It is this diversity that creates habitat for a wide variety of invertebrates, amphibians, birds, plants, and other wildlife, many quite rare. The federally endangered leafy prairie clover and Hine's emerald dragonfly, for example, wouldn't exist here if not for the preserve's calcareous seeps.

In the 1990s, biologist Dr. Daniel Soluk from the Illinois Natural History Survey was studying the Hine's emerald dragonfly at Lockport Prairie when he observed that the periods of time when there was water in the seeps were decreasing. There always had been intervals when these rivulets flowed into the prairie and others when they were parched, but the possibility that the seeps and the moisture in the nature preserve were changing significantly soon became a source of serious concern for Soluk, as well as the staff of the Forest Preserve District of Will County. (The district manages the site in a lease arrangement with the landowner, the Metropolitan Water Reclamation District.) Though the district felt the pressing need for more hydrological information, such studies are costly and no one knew where the money would come from.

The tragic destruction of another dolomite prairie nearby resulted in the payment of a $7.5 million settlement by the site owner, Material Services Corporation, and the establishment of a fund to help restore nearby areas, especially dolomite prairie. In 2000, the Forest Preserve District of Will County applied for money from the settlement fund, which is administered by the U.S. Army Corps of Engineers and the nonprofit group CorLands. The district received $1.4 million to conduct a hydrological study and to take appropriate management action at Lockport Prairie.

"We had to be honest, though," says Marcy DeMauro, deputy director for the district, as she recalls the application for the grant. "We had to admit outright that we might come out at the end of the survey and find out that we couldn't manipulate the hydrology of the system without affecting something else. We might not be able to fix whatever the problem turned out to be."

After two years of study by Graef, Anhalt, Schloemer & Associates, a consulting firm out of Milwaukee, we now know where the prairie's water comes from and where the problems originate. Beginning in 2001, the consultants installed well nests at different depths, both on and off the property, to collect data about groundwater flow. "Groundwater recharge areas are very hard to understand because their boundaries don't follow the surface topography," says Jean Sellar, an ecologist from the U.S. Army Corps of Engineers. "But," Sellar says, "our natural areas are almost all dependent on groundwater, and we have to learn to understand it."

The consultants found that in addition to rainfall, water enters the nature preserve two other ways: from the seeps in the bluffs to the west, and from fissures in the bedrock that allow water from the aquifer to come to the surface. Rainwater recharges the aquifer that supplies groundwater to the nature preserve.

"No environmental area is an island," says Mike Pasteris, the Forest Preserve District of Will County's executive director. "It always exists as part of the earth, as part of a much larger system."

This became acutely apparent at Lockport Prairie, since none of its problems originate within its borders. Lockport Township, for instance, operates a golf course west of Lockport Prairie, on the other side of Route 53. "The golf course had pumps at two wells that it used to fill its irrigation ponds", DeMauro explains. "One was shallow, and the other one deep. When they drew on the shallow well, it showed up as an immediate impact on the water feeding Lockport Prairie. The well nests showed there was a six-inch drop in the entire aquifer after each pumping event."

Rain soaks into the land west of Lockport Prairie, then seeps out of the western bluffs (in blue), sustaining rare pockets of wet dolomite prairie. Protecting neighboring prison land from development also protects some of the groundwater recharge zone. 3D Map: Geographic Information System imagery adapted from: Corlands, Forest Preserve District of Will County, and Graef, Anhalt, Schloemer & Associates.

When this was brought to the attention of Lockport Township, the golf course staff stopped using the shallow well. "They were extremely cooperative once they — and we — knew what was going on, " says DeMauro.

The consultants identified other potential problems from the increasing development of lands near the natural area. First, the town of Crest Hill has new municipal wells going on line, and these may pump at rates in excess of the aquifer's ability to recharge itself. Second, during development, whenever land is paved or planted with dense turf grass, rainwater is no longer absorbed by the earth and the aquifer in the quantities it was before. Instead the rain runs off into sewers, where it is treated and discharged into the Des Plaines River. Third, the chemistry of the water that does enter the natural area may change because it spends less time in the aquifer, and floodwater from the river may enter the natural area more frequently.

Lockport Prairie turned out to be lucky not only because the symptoms of its problems became evident at a time when money was available to pay for a diagnosis — it was also lucky with its neighbors, namely Stateville Prison. Located on the west side of Route 53, Stateville has a 700-acre buffer area maintained mostly in agricultural leases. The absence of development on that open space has allowed absorption of rainfall and recharge of the groundwater through the years.

"I was out golfing one day [on the Lockport Township golf course] when I started thinking about how this would be a great piece to keep as open space," says Brent Hassert, staterepresentative for the 85th district, speaking of the prison buffer. Subsequently, Hassert contacted the Forest Preserve District's Mike Pasteris. Pasteris and the district staff put together a proposal to have the Illinois Department of Corrections (DOC) turn over the 700 acres to the district and to Lockport Township. (Hassert had previously helped Lockport Township obtain its existing golf course from DOC.)

Armed with the information provided by the hydrological study, the district made a compelling case for protection of this parcel as part of the prairie's recharge zone. Though there's no way to keep development off all the land that composes the recharge zone, this parcel is the one directly adjacent to the property, a significant contributor to the preserve's groundwater.

The district has pledged to restore its portion of the recharge zone — approximately 470 acres that will be called the Prairie Bluff Preserve — to prairie, the ideal groundcover for ensuring as much water as possible is absorbed in the aquifer.

"Within a fifteen-minute drive of the Prairie Bluff Preserve, there are well over 150,000 people," says Hassert. "With the rate of development we're experiencing in northern Will County, we'll never have an opportunity like this again."

Hassert has flown over the Prairie Bluff Preserve with the governor's staff, and has initiated legislative action to have the DOC property declared surplus land. These are first steps toward what he and others hope will be the eventual sale of the property for conservation. The proposal will be considered by the legislature either in the fall veto session or in the spring 2005 session.

While by no means final, the Lockport Prairie story does offer encouragement to other natural area managers facing hydrological issues. "So many natural area professionals are terrified by hydrology, and think there's nothing you can do about it,"says Sellar. "Lockport Prairie shows us otherwise."