Jose DeJesus grew up fishing on the Monocacy Creek in Bethlehem.

After he moved and was away from the area for nearly 20 years, he made it a point to come home to visit family and to fish, even organizing his trips to coincide with certain insect hatches.

But in the past few decades, DeJesus said, he’s noticed changes in the creek and the Lehigh Valley.

“The character of the watershed in this area has changed - is changing - not for the better, not at all for the better,” said, DeJesus, vice president of the Monocacy Creek Watershed Association.

A recent water quality report by the Pennsylvania Department of Environmental Protection found that about half of the streams in Lehigh and Northampton Counties were considered “impaired.” That is, they did not meet at least one of four standards in the federal Clean Water Act because of contaminants or other substandard conditions.

In the Lehigh River watershed, nearly 550 miles of streams were considered impaired for aquatic life, according to the report. Nearly 280 miles were labeled impaired for recreation, and 20 miles for fish consumption. The mileage labeled as impaired can overlap. Overall, 22 percent of the streams in the Lehigh River basin were considered impaired.

Though the Monocacy Creek continues to rank among the top sites in Pennsylvania for wild trout per square acre of stream bed, there are worrying signs about its future, DeJesus said.

Development - particularly of massive distribution centers and warehouses - is contributing to pollution and runoff, which are changing the creek. For example, gone are thick beds of Elodea, an aquatic plant that was once abundant in the Monocacy, he said.

The plants helped slow the buildup of silt and gravel, which can choke out macroinvertebrates, such as insects. Sections of the stream are now “barren, wide and shallow,” he said.

“There is basically no aquatic growth anymore,” DeJesus said.

‘Ground zero’

The upper region of the Lehigh River basin is made up of headwaters, wetlands, boreal forests and specially designated waterways that are of high quality.

In the middle basin, pollution threats largely come from abandoned mines, which are sources of runoff with dangerous heavy metals.

And the lower reaches have large communities with aging wastewater infrastructure and “unmitigated increased industrial development,” such as warehouses and logistics centers, said Donna Kohut, campaign manager for the Delaware River Basin for PennFuture.

“This area is ground zero for warehouse development,” DeJesus said. “Acre after acre after acre is going under massive roofs and massive parking lots.”

Since the start of the pandemic, the number of warehouses to meet the needs of e-commerce has picked up, said Erik Broesicke, president of the Monocacy Chapter of Trout Unlimited.

He said the region’s proximity to an airport and major highways make it a natural transportation hub accessible within a few hours to millions of people in major metropolitan markets. The warehouses allow retail giants like Amazon to fulfill orders and make deliveries as quickly as possible.

“Logistically, this is a pretty important area for that kind of development,” he said.

Jake Terkanian, a senior vice president for CBRE Philadelphia, a firm specializing in commercial real estate, said on the company’s website that the pandemic “supercharged demand” for these kinds of warehouses and distribution centers.

Massive warehouses, with walls like medieval castles, dominate the streetscape of a section of Hanoverville Road, north of Bethlehem. That road, though, is merely a microcosm of the larger warehouse development trend in the region.

From 2017-21 in Lehigh and Northampton Counties, more than 27 million square feet of warehouse space - or the equivalent of 186 Costco stores - was approved for construction, according to the Lehigh Valley Planning Commission.

From the air, the buildings are featureless and virtually indistinguishable from one another. Drone footage reveals acre upon acre of smooth black roofing punctuated by heating and air-conditioning vents and mechanicals. On the sides of the buildings, long rows of trailers line up to loading platforms like piglets suckling at a gigantic sow.

Many warehouses and industrial buildings along the along I-78 corridor in Lehigh County have been built on land that was once used for farming, Kohut said.

“That convenience of shopping, consumption and delivery - that has a very real impact on our water quality,” she said.

Some companies built warehouses on spec in the hopes of enticing tenants, which then leads to more warehouses, which hatch like mosquitoes after a summer rain.

The rapacious rate of development shows no signs of letting up, either.

With 493 million square feet of total inventory, the Southern New Jersey/Eastern Pennsylvania region is the second-largest big-box market in North America, according to a March report by CBRE.

Last year in the Southern New Jersey/Eastern Pennsylvania market, more than 24 million square feet was built and twice that amount was under construction. Developers remained bullish as vacancy rates dropped and rents rose, the report said.

Dangers of development

Big-box warehouses can affect water quality in a number of ways: Expansive parking lots and building footprints contribute to acres of impervious surfaces, which can act as a sluiceway for contaminants, such as car oil and fluids, to get into streams.

Rather than allowing precipitation to be absorbed gradually into the soil, the paved surfaces can send volumes of water rushing into streams.

That kind of water volume and speed - especially in a time of climate change that will bring more frequent, intense storms - can change the contours of a stream and make it wider and shallower.

The Monocacy Creek, a tributary of the Lehigh, faces such challenges.

Aquifers naturally have lower-temperature water and feed the creek but as those underground water supplies have been tapped to meet the needs of more development, aquifer levels have lowered, meaning there is less cold water available for the creek.

And any surface waters that flow from asphalt and other impenetrable surfaces will have a higher temperature as they flow into the Monocacy. All of those changes can make the waterway less hospitable to cold-water fish, such as trout.

“Trout are somewhat the canary in the coal mine” because they don’t tolerate high temperatures, which can result from climate change and adverse impacts from development, Broesicke said.

Still, the tributaries to the Lehigh River are “pretty productive” in terms of fishing and water quality, he said.

In the face of growing development, Broesicke described himself as “moderately concerned” about the Lehigh River basin over the next five to 10 years.

“The Lehigh River was dead back in the day,” he said. Now, he said: “The fishing’s pretty good. A lot of people are surprised by that.”

Vicious circle

Streams that have less than the very highest state designations of protection can become degraded by less-restrictive rules for development.

That means the water quality can be stymied from improving. The better the quality, the higher protection status a stream can potentially gain, but without those protections, more development could be allowed, which, in turn, could allow a waterway to be further polluted.

“Unless the rate of development is reduced or safeguards are put into place, the health of local creeks and streams will continue to degrade,” Kohut said in written comments to the DEP about its water quality report. The Lehigh River watershed had not been reassessed in several years, Kohut added, with the numbers in the 2022 report rolled forward from previous years. She called on the DEP to prioritize reassessing the basin’s streams in its 2024 report.

“The health of this watershed directly impacts tens of thousands of residents and the economic vitality of the region,” she wrote. “The Lehigh River is the lifeblood of the outdoor recreation and tourist industries, and it also provides much-needed recreation opportunities for low-income communities of color in the densely populated Lehigh Valley.”

Kohut said visitors come to Pennsylvania to enjoy its natural beauty, hike, fish, raft or window shop in one of its river communities.

“We don’t have tourists visit the regions of Pennsylvania to tour the warehouse facilities,” she said.

Michael Mele contributed reporting.