Looking up into the headwaters of Sawmill Creek, Stuart Lehman pointed out the stream characteristics that were good for fish. There was a good mixture of pools, riffles, and runs. That variety provided for water high in oxygen, plenty of areas for fish and aquatic insects to lay eggs, and lots of leaf particles to provide food.

“This is pretty good fish habitat all through there,” said Lehman, a biologist with the Maryland Department of Natural Resources.

As Lehman pointed this out, he was standing atop thousands of cubic yards of fill. Sawmill Creek, in fact, was flowing through four large culverts about 20 feet directly below him. The earth shook as bulldozers, dump trucks, and other construction vehicles roared past, working to complete a new section of Maryland Route 100. A stream of jets leaving Baltimore-Washington International Airport roared overhead, making conversation difficult.

Since World War II, the Sawmill Creek watershed has seen a steady procession of suburban and commercial development, airport expansion, and the related road construction. And development has not stopped. Signs throughout the upper watershed advertise new housing developments and industrial parks.

The creek got its name from a sawmill built near its mouth during the 1700s to take advantage of the area’s trees. But today, only about 1,600 acres remains forested. About 3,100 acres are developed.

These changes have had a profound impact on the watershed and its resources. Stream beds have been greatly altered, fish migration is blocked at several points, stream flows fluctuate wildly, and the water is polluted. Few species of fish make it to the good habitat conditions that Lehman was pointing out, which was in the top third of the 8.4-square-mile watershed. Much of the rest of the drainage is so disturbed that only about two-thirds of the roughly 30 species that would be expected in a “pristine” creek are routinely found.

The remaining species are those more tolerant of degraded habitats. “You lose your sensitive fish species first,” Lehman said. “There are fewer aquatic insects in the stream so there is less for them to eat. You get species that will take any kind of food that is available.”

Lehman’s job is to change this. He coordinates the the state’s multi-agency targeted watershed project which was established in the late 1980s. Sawmill Creek and three other targeted watersheds are now the focus of comprehensive planning and restoration efforts to see what can be done to repair decades of damage to the systems. Of the four, Sawmill Creek was the most urbanized and degraded. Officials hope lessons learned from it, and the other watersheds, will aid restoration efforts elsewhere.

The objective is to forgo looking at the watershed on a permit-by-permit or project-by-project basis, and instead look at the drainage basin in its entirety. By doing so, biologists could see the cumulative impacts of many small actions which — by themselves — may seem insignificant.

“If you want to deal with water quality,” Lehman said, “you sort of have to deal with the area that defines the problem you’re working on, and watersheds are the appropriate way to do that.”

“Do you smell something?” asked Larry Lubbers, a DNR biologist, as he stood near the headwaters of Muddy Bridge Branch — the largest tributary of Sawmill Creek. The air reeked of chemicals. “There are only two streams I know of that smell like this,” said Lubbers, Sawmill Creek restoration team leader. “This one, and one on the other side of the airport.”

Oil, grease and other chemicals — particularly deicers used in the wintertime — flow into the headwaters of the stream just a short way off. Monitoring after storms found that, in some cases, deicers accounted for 20 percent of what was flowing into the headwaters. Chemicals in the de-icers have caused tissue damage in fish downstream.

It was only one of the many impacts identified during the initial monitoring phase of the wastershed project which began in fall 1989. While walking through a portion of Sawmill Creek’s main stem, biologists spotted oil bubbling up around their waders. It turned out that underground pipes at a nearby oil storage facility was leaking. Exactly what impact it was having on the creek, though, is hard to say.

“If it was the only thing wrong in this stream, you might be able to sort out the difference in the benthic community upstream and downstream from the leak,” Lubbers said, “but there’s so much wrong with this stream, it’s hard to sort out the impacts.”

Indeed, the Sawmill Creek watershed is packed with problems. It is home to 17,000 people — parts of the communities of Glen Burnie and Ferndale — many of whom live in homes built in the three decades after World War II. That was before storm water controls were required for new development, so rain water is flushed straight from streets into streams.

This discharge — at high velocities — had destabilized and eroded the banks of Sawmill Creek and some of its tributaries. In places, stream beds have been cut more than 5 feet deep by the rushing water. Water whipped through one stream so rapidly after a storm that it ripped out a net biologists had strung for a migratory fish survey. “It just blew our net out,” Lehman said. “We never did find it.”

Behind some developments, streams have been dredged into straight channels to keep them from meandering into people’s back yards. Often, these sites have no tree cover, which is needed to shade the water to protect it from quick temperature fluctuations and to provide a food source for aquatic organisms through falling leaves.

In other places, narrow culverts have restricted stream flow, creating plains of shifting muck behind them. “When you have boots on and walk around you sink in,” Lubbers said. “It’s like quicksand in some of these areas.”

Streams with unstable banks and muck-covered bottom provide poor fish habitat. Fish — and the insects they feed on — require solid surfaces to hide among and lay their eggs in. Fish have also suffered from a variety of contaminants that have been flushed off the streets.

Those contaminants will not be greatly diluted by the streams’ normal water flow, which today is chronically low. Much of the natural ground water that once fed the streams throughout the watershed has been tapped by wells. Ground water withdrawals have increased 300 percent from 1965 to 1985. Once pumped out of the ground and used, that water goes down the drain and to a waste water treatment plant outside the watershed.

The U.S. Geological Survey estimated the base flow in Sawmill Creek — attributable to ground water sources — at 7.4 cubic feet per second in the late 1940s, but that rate fell to less than 1 cfs in the late 1980s. That reduction has nearly eliminated all fish and insect habitat in one of the stream’s tributaries.

Ironically, Sawmill Creek once had one of the highest baseflows per square mile of any watershed in the region. “That was one reason why there was so much ground water development there,” Lubbers said. “It looked like an unlimited resource.”

After the multi-year monitoring program in Sawmill Creek, it became obvious that the most important problems in the watershed were related to hydrology. There was either too much water immediately after storms, or too little at other times.

Looking at the watershed as a whole shed new light on these issues, particularly the impact of water withdrawals. The cumulative biological impact from the wells had never been examined before, and officials were not aware that base flows through the watershed had fallen so far below historic levels.

Anne Arundel County had been looking into rebuilding some of the well fields which had been drilled in the 1940s and 50s. Lubbers said the DNR is now working with the county to get water from outside — Baltimore, for example, has a surplus.

One of the challenges of the Sawmill Creek project is trying to restore the watershed’s water quality and habitat with little new money. To do that, officials have worked to best use tools provided by existing programs.

The ongoing development in the watershed has provided some benefits to the restoration effort. Owners of about 17 percent of the property in the watershed were seeking building permits in a recent year. County officials now routinely work with state biologists to make sure the changes will not adversely impact the watershed and — in some cases — projects can be modified to benefit the system.

By working with the State Highway Administration, which is overseeing a flurry of road construction and reconstruction in the watershed, five fish blockages will be removed at highway crossings as the roads are rebuilt.

When the extension of Route 100 destroyed 5 acres of forested wetlands — which under state law requires 10 acres of wetland creation or “mitigation” — highway planners had originally considered placing the new acreage several miles away on the main stem Patapsco River.

But with detailed information about the Sawmill Creek watershed in hand, the restoration team was able to have the mitigation kept within the watershed. The mitigation project will now involve a major restoration along Muddy Bridge Branch which will include projects that will help control runoff, stabilize the rapidly eroding stream bank, and provide flood control. “We know so much about the problems here, we could recommend a lot of remedial work that would help this watershed,” Lubbers said.

The airport’s discharge permit was up for renewal, and officials there are working closely with the Maryland Department of the Environment to design a storm water system that will keep deicers and other chemicals from reaching the water. In addition, BWI has developed a comprehensive forest and wetland management plan that will help filter the runoff from the airport’s runways and buildings.

MDE is also working with the oil storage facility to fix the leaking pipe problem.

Because of its small size, officials hope to see results from their actions within a few years. The objective is not to restore pre-settlement conditions — officials acknowledge that is impossible — but to see quantifiable improvements in habitat conditions, water quality, and possibly species diversity.

“What we’re looking for is a stable, viable ecosystem — not pristine conditions,” Lubbers said. For example, he said, the goal for restoring ground water flow is not historical levels, but about 4 cfs — roughly half the pre-development flow. Likewise, he does not expect to see all the native fish species return, but he would like to see a more stable population rather than the widely fluctuating numbers now monitored.

As recently as World War II, Lubbers said, Sawmill Creek was healthy enough that the state had stocked extra game fish in it so people from Baltimore could ride there on the trolley lines and fish without running down fuel supplies by driving into the country.

Now, the state’s new light rail system extends into the watershed. Lubbers hopes that through the targeted watershed program, there will be a return of healthy fish stocks to Sawmill Creek to coincide with the return of mass transit.