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The Aquetong Creek Restoration Project is situated within the former basin of Aquetong Lake, which was a 15- acre impoundment formed in 1870 by the construction of an earthen dam on Aquetong Creek. The cold-water limestone spring, which flows at a rate of about 2,000 gallons per minute at approximately 53ºf, is known to be the largest of its kind in the 5-county Philadelphia region, and one of the largest in the state of Pennsylvania.
In 2015, the Township of Solebury commenced the restoration of Aquetong Spring Park, first with a dam breach followed by a large stream restoration, reforestation, and invasive species removal. In September, the park was officially reopened to the public following a ribbon cutting ceremony. The event featured a blessing from the Lenni-Lenape Turtle Clan, the original inhabitants of the land.
Prior to European settlement, the Lenni-Lenape Tribe inhabited a village close to the spring and designated the spring “Aquetong”, meaning “at the spring among the bushes.” After an outbreak of smallpox, however, the tribe abandoned the village. William Penn acquired Aquetong Spring in the early 1680’s as part of his peaceful treaty with Lenni-Lenape. The park land transferred hands many times before it was owned by Aquetong Township.
The dependability of the water flow made the Aquetong Creek an ideal location for mills. As of the early 1800’s, Aquetong Spring is known to have supplied enough water to turn two grist mills regularly throughout the year, and to have concurrently powered numerous mills including a paper mill, a fulling mill, two merchant mills, four sawmills, and an oil mill.
Around 1870, the 15-acre Aquetong Lake was created by constructing a dam at the east end of the property. This provided additional power for the local mills and a recreation area for the public. A fish hatchery was constructed at the base of the spring outfall, portions of which can still be viewed today. Shad, brook trout, and terrapin turtles were raised in the hatchery, which was available for public viewing at a cost of 25 cents per person.
Then, in 1993, the Pennsylvania Fish and Boat Commission acquired the property. A few years later, with the support of Bucks County Trout Unlimited, Solebury Township began negotiating to obtain ownership of the site. Around 1996, the State performed emergency repairs on the dam; a six-foot section of the outlet structure was removed in order to take pressure off the aging barrier. This lowered the level of the lake and added about 80 feet of wetlands to the western shoreline. However, it was recognized that a complete repair of the dam could cost over $1 million and might not be the best choice for the environment.
In 2009, after almost 15 years of negotiations, Solebury Township gained control of the property, with the goal of preserving this important natural resource. It purchased the lake and surrounding properties from the state and obtained a 25-year lease. The Township’s total costs were substantially reduced because it received a large credit in exchange for its commitment to repair the dam in the future, as well as funding from the Bucks County Natural Areas Program toward the purchase.
Following the purchase, the Township engaged in a five-year process of community outreach and consultation with environmental experts in which it considered alternatives for the Aquetong Lake dam. Choices included rebuilding the dam in its then-current form, creating a smaller lake with a cold-water bypass into Aquetong Creek, or breaching the dam and restoring a free-flowing stream. Ultimately, recognizing that the lake was a thermal reservoir which introduced warm water into Aquetong Creek and eventually into the streams and river, the Township decided to breach rather than restore the dam, and return the site to its natural state.
The Aquetong Restoration Project got underway in 2015, and Solebury Township breached the historic mill dam in Aquetong Spring Park to convert the former lake into a natural area with a free-flowing, cold water stream capable of supporting native brook trout.
After the dam breach, areas of active erosion were observed along the mainstem and a major tributary of Aquetong Creek. The steep, eroding banks, increased the sediment load to the Creek’s sensitive aquatic habitat.
As with most dam removal projects, a degree of stewardship is necessary to enhance the establishment of desirable, beneficial vegetation. Additionally, Solebury Township wanted to control invasive species in Aquetong Spring Park and replant the project area with native species.
The Township secured funding to construct riparian buffers, implement streambank stabilization measures, establish trout habitat structures within the mainstem and its tributary, control invasive species, and implement a woodland restoration plan. The project was funded by a $250,000 grant from the PA Department of Conservation and Natural Resources, with an equal match from the Township. Additional grants for the project were provided by the PA Department of Community and Economic Development and the National Fish and Wildlife Foundation.
Solebury Township contracted Princeton Hydro to design the stabilization of the stream channel and floodplains within the former impoundment, monitor the stream and wetlands before and after implementation, and obtain the permits for the restoration of the former impoundment. Princeton Hydro team members designed the restoration of the main channel and tributary to reduce channel and bank erosion while supporting the brook trout habitat.
After gathering and reviewing the existing data for the site, Princeton Hydro conducted field investigations to inform and guide the final design including surveying cross sections and performing fluvial geomorphological assessments of the existing channel. Pebble counts were performed, cross sections were analyzed, and existing hydrological data was reviewed to inform the design. Simultaneously, an invasive species control and woodland restoration plan was developed for the park.
Data collected from the site was used to develop a geomorphically-appropriate, dynamically-stable design. The proposed channel design included excavation of impounded sediment to create stable channel dimensions, the addition of gravel, cobble, and boulder substrate where original/existing channel substrates were absent or insufficient, and the installation of large wood features to create aquatic habitat and enhance stability of channel bed and banks.
The banks and riparian corridor were vegetated with native seed, shrubs and trees to ultimately create a wooded, shaded riparian buffer. The design ultimately stabilized the streambanks with features that double as trout habitat and replanted the surrounding park with native vegetation.
The project was replanted with an incredibly diverse set of native species that included:
In addition to restoring the stream in the former impoundment, as a part of its Strategic Master Plan for Aquetong Spring Park, Solebury Township expanded its focus of the restoration project to include another 20 acres of forested land.
For this, Solebury developed a Woodland Restoration Plan which identified over 1,000 diseased forest trees, composed mostly of ash (Fraxinus sp.) and black walnut (Juglans nigra). It was the Township’s objective to remove the hazardous trees, re-establish a native woodland community, and establish an invasive species management program.
The trees removed as a part of this effort were repurposed for the stream restoration project and used for habitat features, stream stabilization measures, and park features (i.e. benches).
Princeton Hydro also provided stormwater design support for adjacent areas in Aquetong Spring Park, including multiple stormwater connections to the main tributary. After completion, Princeton Hydro provided bid assistance, developed a probable cost, drafted technical specifications, and produced a bid package to assist Aquetong Township in bringing the project to construction.
This restoration success could not have been possible without the hard work of so many dedicated project partners: Aquetong Spring Advisory Council, Bucks County Trout Unlimited, Solebury Township, Aquetong Township, Simone Collins Landscape Architects, PA Department of Conservation and Natural Resources, PA Department of Community and Economic Development, the National Fish and Wildlife Foundation, Lenni-Lenape Turtle Clan, and Princeton Hydro.
Princeton Hydro specializes in the planning, design, permitting, implementing, and maintenance of ecological rehabilitation projects. To learn more about our watershed restoration services, click here. To learn about some of our award-winning restoration projects check out our blogs about the Pin Oak Forest Conservation Area freshwater wetland restoration project:
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