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WP_Query Object ( [query] => Array ( [category_name] => engineering ) [query_vars] => Array ( [category_name] => engineering [error] => [m] => [p] => 0 [post_parent] => [subpost] => [subpost_id] => [attachment] => [attachment_id] => 0 [name] => [pagename] => [page_id] => 0 [second] => [minute] => [hour] => [day] => 0 [monthnum] => 0 [year] => 0 [w] => 0 [tag] => [cat] => 31 [tag_id] => [author] => [author_name] => [feed] => [tb] => [paged] => 1 [meta_key] => [meta_value] => [preview] => [s] => [sentence] => [title] => [fields] => all [menu_order] => [embed] => [category__in] => Array ( [0] => 36 ) [category__not_in] => Array ( ) [category__and] => Array ( ) [post__in] => Array ( ) [post__not_in] => Array ( ) [post_name__in] => Array ( ) [tag__in] => Array ( ) [tag__not_in] => Array ( ) [tag__and] => Array ( ) [tag_slug__in] => Array ( ) [tag_slug__and] => Array ( ) [post_parent__in] => Array ( ) [post_parent__not_in] => Array ( ) [author__in] => Array ( ) [author__not_in] => Array ( ) [search_columns] => Array ( ) [ignore_sticky_posts] => [suppress_filters] => [cache_results] => 1 [update_post_term_cache] => 1 [update_menu_item_cache] => [lazy_load_term_meta] => 1 [update_post_meta_cache] => 1 [post_type] => [posts_per_page] => 10 [nopaging] => [comments_per_page] => 5 [no_found_rows] => [order] => DESC ) [tax_query] => WP_Tax_Query Object ( [queries] => Array ( [0] => Array ( [taxonomy] => category [terms] => Array ( [0] => engineering ) [field] => slug [operator] => IN [include_children] => 1 ) [1] => Array ( [taxonomy] => category [terms] => Array ( [0] => 36 ) [field] => term_id [operator] => IN [include_children] => ) ) [relation] => AND [table_aliases:protected] => Array ( [0] => ph_term_relationships [1] => tt1 ) [queried_terms] => Array ( [category] => Array ( [terms] => Array ( [0] => engineering ) [field] => slug ) ) [primary_table] => ph_posts [primary_id_column] => ID ) [meta_query] => WP_Meta_Query Object ( [queries] => Array ( ) [relation] => [meta_table] => [meta_id_column] => [primary_table] => [primary_id_column] => [table_aliases:protected] => Array ( ) [clauses:protected] => Array ( ) [has_or_relation:protected] => ) [date_query] => [queried_object] => WP_Term Object ( [term_id] => 31 [name] => Engineering [slug] => engineering [term_group] => 0 [term_taxonomy_id] => 31 [taxonomy] => category [description] => [parent] => 0 [count] => 93 [filter] => raw [term_order] => 4 [cat_ID] => 31 [category_count] => 93 [category_description] => [cat_name] => Engineering [category_nicename] => engineering [category_parent] => 0 ) [queried_object_id] => 31 [request] => SELECT SQL_CALC_FOUND_ROWS ph_posts.ID FROM ph_posts LEFT JOIN ph_term_relationships ON (ph_posts.ID = ph_term_relationships.object_id) LEFT JOIN ph_term_relationships AS tt1 ON (ph_posts.ID = tt1.object_id) WHERE 1=1 AND ( ph_term_relationships.term_taxonomy_id IN (31) AND tt1.term_taxonomy_id IN (36) ) AND ((ph_posts.post_type = 'post' AND (ph_posts.post_status = 'publish' OR ph_posts.post_status = 'acf-disabled'))) GROUP BY ph_posts.ID ORDER BY ph_posts.menu_order, ph_posts.post_date DESC LIMIT 0, 10 [posts] => Array ( [0] => WP_Post Object ( [ID] => 12550 [post_author] => 1 [post_date] => 2023-05-16 14:22:25 [post_date_gmt] => 2023-05-16 14:22:25 [post_content] => In the late 1920s, the U.S. government began allocating funds for road construction in U.S. national forests. This led to hundreds of thousands of culverts being built and installed across the country for the purpose of moving water quickly and efficiently underneath the roadways to prevent flooding, minimize erosion, and provide pathways for stormwater. However, culverts have had an unintended and significant consequence: they block the migration routes of some fish and aquatic organisms. Culverts that are undersized, improperly placed, or designed with smooth featureless surfaces can impede or totally block fish and aquatic species from passing. Culverts with extremely high velocity flows make it incredibly difficult for aquatic organisms to navigate upstream, and extremely low velocity flows make it hard for fish to pass in either direction. The high-velocity flows can erode the stream channel immediately downstream of the culvert, which can leave the culvert pipe perched. This elevation above the water channel makes it impossible for organisms to pass through. Debris can also collect in the culvert, not only blocking fish passage, but water as well. In addition to blocking the upstream passage of fish and other aquatic species, some culverts disrupt the normal stream movements of some macroinvertebrates, which are key components of these stream ecosystems, an important food source to countless species, and play a critical role in the cycling of energy and nutrients throughout stream ecosystems. Disruptions to the movement and dispersal of stream macroinvertebrates can reduce available habitat, lead to genetic isolation of some populations, and cause extirpation of critical species. When populations splinter, it causes a reduction in genetic diversity, which can lead to the spread of more invasive species and many other ecological issues. [caption id="attachment_12565" align="aligncenter" width="651"] Diagram created by NOAA Fisheries[/caption] While culverts serve an important function in road construction and flood prevention, their impact on aquatic organisms must be taken into consideration. Finding solutions that both allow for efficient water flow and enable safe aquatic migration is crucial in preserving the health of our waterways and their ecosystems. Addressing Outdated, Unsafe, and Obsolete Culverts A shift in the 1980s recognized the importance of redesigning road-stream crossings for several reasons, including restoring aquatic organism passage and maintaining flood resilience. Between 2008 and 2015, U.S. Forest Service (USFS) partnered with more than 200 organizations in the Legacy Roads and Trails Program to replace 1,000+ culverts across the country. The aim of the program was to upgrade culverts to emulate natural streams and to allow fish and wildlife to pass more naturally both upstream and downstream. Replacing culverts with structures that better facilitate the movement of both water and aquatic organisms has benefits beyond restoring critical ecosystems and improving biodiversity. Ecological restoration creates jobs, stimulates outdoor recreation and local economic activity, and generates long-term economic value. Princeton Hydro has a strong history in designing connectivity-friendly road-stream crossings and restoring/replacing outdated culverts. Our team of engineers and scientists has been directly involved with hundreds of stream and ecosystem restoration projects throughout the Northeast. For several years, Princeton Hydro has partnered with NY-NJ Harbor & Estuary Program (HEP) to plan and design for aquatic connectivity through climate-ready infrastructure. Created by the U.S. Environmental Protection Agency (USEPA) at the request of the governors of New York and New Jersey, HEP develops and implements plans that protect, conserve and restore the estuary, and aquatic connectivity is a key focus area for HEP and its partners. Most recently, HEP partnered with Princeton Hydro to address hydraulic capacity issues at priority road-stream crossings in New Jersey’s South River and Lower Raritan River watersheds. The Princeton Hydro team developed a 30% engineering plan for a priority road-stream crossing – the Birch Street crossing over the Iresick Brook in Old Bridge, NJ. Iresick Brook Culvert Restoration Iresick Brook is upstream from Duhernal Lake, located at the end of the free-flowing South River, which feeds into the Raritan River, and ultimately flows into Raritan Bay. Duhernal Lake is dammed at the outlet so there is little to no connectivity downstream from the Iresick Brook sub-watershed. The watershed is highly dendritic (meaning the drainage pattern follows a tree-like shape) with many small streams running through it, some of them ephemeral. The Iresick Brook 5 (IB5) culvert, located in Old Bridge Township, New Jersey, is an undersized double culvert in poor condition with an eroding streambank. This culvert was chosen as a restoration priority primarily due its inadequate sizing (both pipes are only 3-feet in diameter). The outdated infrastructure blocks the passage of fish and other aquatic organisms, and it can only accommodate a 50-year storm event. Once the IB5 culvert was identified as the priority site, Princeton Hydro completed a site investigation, which included a geomorphic assessment, site observations, and simplified site survey of the channel alignment, profile, and cross sections both upstream and downstream of the culvert. At the time of the survey, flow was only a couple inches deep in the channel and incredibly slow-moving, especially in the upstream reach. Despite the low flow at the time of the survey, during storm events, the stream experiences extremely high velocities. The undersized culvert creates hydraulic constriction and subsequently a velocity barrier that prevents passage. Additionally, when the high-flow stream water is forced through the small pipes, it creates a firehose effect, which has led to the formation of a 60-foot-long scour hole at the culvert outlet. Substrate from the scour hole has been washed downstream, forming an island of large sand and small gravel. Approximately 155 feet upstream of the culvert is a channel-spanning v-notch weir comprised of a combination of sheet pile and timber. The weir appears to be a historical stream gauge that is highly degraded and creates an artificially perched channel. The upstream channel also contains woody debris, which gets caught at the culvert, blocking water flow and organism passage. For the design process, Princeton Hydro used the USFS Stream Simulation Design, an gold-standard ecosystem-based approach for designing and constructing road-stream crossings that provide unimpeded fish and other aquatic organism passage through the structure. The Stream Simulation, a required standard on USFS road projects, integrates fluvial geomorphology concepts and methods with engineering principles to design a road-stream crossing that contains a natural and dynamic channel through the structure so that fish and other aquatic organisms will experience no greater difficulty moving through the structure than if the crossing did not exist. The design also incorporated utility constraints (gas line, sewer line, drinking water main, and stormwater outlet), a longitudinal profile assessment, channel capacity and slope analysis, and a simplified hydrologic & hydraulic assessment. Ultimately, Princeton Hydro recommended that HEP replace the existing culvert with a Contech Precast O-321 culvert, or similar alternative. The proposed design increases the culvert opening area and allows for significant increases in flow capacity. This culvert replacement project has the potential to reduce local flood risk and restore aquatic organism passage to the reach of Iresick Brook. To get a more detailed look at the IB5 culvert project and learn more about HEP and its partnership with Princeton Hydro, click below for a full presentation from Isabelle Stinnette of HEP and Jake Dittes, PE of Princeton Hydro: [embed]https://www.youtube.com/watch?v=d-qbV9EG9Ss[/embed] Prioritizing Culvert Restoration Aquatic connectivity is crucial for improving healthy aquatic ecosystems and managing severe storms and flooding. Increases in rainfall due to climate change makes investing in these improvements even more of a growing priority. With so many culverts in place, it can be difficult to know which culvert restoration projects to prioritize. We worked with HEP to create a toolkit for addressing problematic road-stream crossings. The easy-to-use matrix helps to prioritize potential projects and identify solutions for problem culverts and relative cost solutions. The toolkit was just recently released to the public with the hope that it will be used as a template to promote the development of more resilient and environmentally-friendly infrastructure. Click here to get more info and download. [post_title] => Restoring Road-Stream Crossings to Support Fish Passage [post_excerpt] => [post_status] => publish [comment_status] => open [ping_status] => open [post_password] => [post_name] => restoring-road-stream-crossings-to-support-fish-passage [to_ping] => [pinged] => [post_modified] => 2025-07-29 00:00:34 [post_modified_gmt] => 2025-07-29 00:00:34 [post_content_filtered] => [post_parent] => 0 [guid] => https://princetonhydro.com/?p=12550 [menu_order] => 0 [post_type] => post [post_mime_type] => [comment_count] => 0 [filter] => raw ) [1] => WP_Post Object ( [ID] => 10290 [post_author] => 1 [post_date] => 2022-02-17 19:39:19 [post_date_gmt] => 2022-02-17 19:39:19 [post_content] => 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. SITE HISTORY 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. [caption id="attachment_10303" align="aligncenter" width="832"] The Aquetong Creek restoration site is located in Solebury Township, Bucks County, PA, and encompasses the boundaries of the former Aquetong Lake. The Lake was a 15-acre impoundment formed in 1870 by the construction of an earthen dam on Aquetong Creek. The Creek flows approximately 2.5 miles from Ingham Spring to join with the Delaware River in New Hope, PA.[/caption] RESTORATION WORK 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 the late 1920s, the U.S. government began allocating funds for road construction in U.S. national forests. This led to hundreds of thousands of culverts being built and installed across the country for the purpose of moving water quickly and efficiently underneath the roadways to prevent flooding, minimize erosion, and provide pathways for stormwater.
However, culverts have had an unintended and significant consequence: they block the migration routes of some fish and aquatic organisms.
Culverts that are undersized, improperly placed, or designed with smooth featureless surfaces can impede or totally block fish and aquatic species from passing. Culverts with extremely high velocity flows make it incredibly difficult for aquatic organisms to navigate upstream, and extremely low velocity flows make it hard for fish to pass in either direction. The high-velocity flows can erode the stream channel immediately downstream of the culvert, which can leave the culvert pipe perched. This elevation above the water channel makes it impossible for organisms to pass through. Debris can also collect in the culvert, not only blocking fish passage, but water as well.
In addition to blocking the upstream passage of fish and other aquatic species, some culverts disrupt the normal stream movements of some macroinvertebrates, which are key components of these stream ecosystems, an important food source to countless species, and play a critical role in the cycling of energy and nutrients throughout stream ecosystems. Disruptions to the movement and dispersal of stream macroinvertebrates can reduce available habitat, lead to genetic isolation of some populations, and cause extirpation of critical species. When populations splinter, it causes a reduction in genetic diversity, which can lead to the spread of more invasive species and many other ecological issues.
While culverts serve an important function in road construction and flood prevention, their impact on aquatic organisms must be taken into consideration. Finding solutions that both allow for efficient water flow and enable safe aquatic migration is crucial in preserving the health of our waterways and their ecosystems.
A shift in the 1980s recognized the importance of redesigning road-stream crossings for several reasons, including restoring aquatic organism passage and maintaining flood resilience. Between 2008 and 2015, U.S. Forest Service (USFS) partnered with more than 200 organizations in the Legacy Roads and Trails Program to replace 1,000+ culverts across the country. The aim of the program was to upgrade culverts to emulate natural streams and to allow fish and wildlife to pass more naturally both upstream and downstream.
Replacing culverts with structures that better facilitate the movement of both water and aquatic organisms has benefits beyond restoring critical ecosystems and improving biodiversity. Ecological restoration creates jobs, stimulates outdoor recreation and local economic activity, and generates long-term economic value.
Princeton Hydro has a strong history in designing connectivity-friendly road-stream crossings and restoring/replacing outdated culverts. Our team of engineers and scientists has been directly involved with hundreds of stream and ecosystem restoration projects throughout the Northeast.
For several years, Princeton Hydro has partnered with NY-NJ Harbor & Estuary Program (HEP) to plan and design for aquatic connectivity through climate-ready infrastructure. Created by the U.S. Environmental Protection Agency (USEPA) at the request of the governors of New York and New Jersey, HEP develops and implements plans that protect, conserve and restore the estuary, and aquatic connectivity is a key focus area for HEP and its partners.
Most recently, HEP partnered with Princeton Hydro to address hydraulic capacity issues at priority road-stream crossings in New Jersey’s South River and Lower Raritan River watersheds. The Princeton Hydro team developed a 30% engineering plan for a priority road-stream crossing – the Birch Street crossing over the Iresick Brook in Old Bridge, NJ.
Iresick Brook is upstream from Duhernal Lake, located at the end of the free-flowing South River, which feeds into the Raritan River, and ultimately flows into Raritan Bay. Duhernal Lake is dammed at the outlet so there is little to no connectivity downstream from the Iresick Brook sub-watershed. The watershed is highly dendritic (meaning the drainage pattern follows a tree-like shape) with many small streams running through it, some of them ephemeral.
The Iresick Brook 5 (IB5) culvert, located in Old Bridge Township, New Jersey, is an undersized double culvert in poor condition with an eroding streambank. This culvert was chosen as a restoration priority primarily due its inadequate sizing (both pipes are only 3-feet in diameter). The outdated infrastructure blocks the passage of fish and other aquatic organisms, and it can only accommodate a 50-year storm event.
Once the IB5 culvert was identified as the priority site, Princeton Hydro completed a site investigation, which included a geomorphic assessment, site observations, and simplified site survey of the channel alignment, profile, and cross sections both upstream and downstream of the culvert.
At the time of the survey, flow was only a couple inches deep in the channel and incredibly slow-moving, especially in the upstream reach. Despite the low flow at the time of the survey, during storm events, the stream experiences extremely high velocities. The undersized culvert creates hydraulic constriction and subsequently a velocity barrier that prevents passage. Additionally, when the high-flow stream water is forced through the small pipes, it creates a firehose effect, which has led to the formation of a 60-foot-long scour hole at the culvert outlet. Substrate from the scour hole has been washed downstream, forming an island of large sand and small gravel.
Approximately 155 feet upstream of the culvert is a channel-spanning v-notch weir comprised of a combination of sheet pile and timber. The weir appears to be a historical stream gauge that is highly degraded and creates an artificially perched channel. The upstream channel also contains woody debris, which gets caught at the culvert, blocking water flow and organism passage.
For the design process, Princeton Hydro used the USFS Stream Simulation Design, an gold-standard ecosystem-based approach for designing and constructing road-stream crossings that provide unimpeded fish and other aquatic organism passage through the structure. The Stream Simulation, a required standard on USFS road projects, integrates fluvial geomorphology concepts and methods with engineering principles to design a road-stream crossing that contains a natural and dynamic channel through the structure so that fish and other aquatic organisms will experience no greater difficulty moving through the structure than if the crossing did not exist.
The design also incorporated utility constraints (gas line, sewer line, drinking water main, and stormwater outlet), a longitudinal profile assessment, channel capacity and slope analysis, and a simplified hydrologic & hydraulic assessment.
Ultimately, Princeton Hydro recommended that HEP replace the existing culvert with a Contech Precast O-321 culvert, or similar alternative. The proposed design increases the culvert opening area and allows for significant increases in flow capacity. This culvert replacement project has the potential to reduce local flood risk and restore aquatic organism passage to the reach of Iresick Brook.
Aquatic connectivity is crucial for improving healthy aquatic ecosystems and managing severe storms and flooding. Increases in rainfall due to climate change makes investing in these improvements even more of a growing priority. With so many culverts in place, it can be difficult to know which culvert restoration projects to prioritize.
We worked with HEP to create a toolkit for addressing problematic road-stream crossings. The easy-to-use matrix helps to prioritize potential projects and identify solutions for problem culverts and relative cost solutions.
The toolkit was just recently released to the public with the hope that it will be used as a template to promote the development of more resilient and environmentally-friendly infrastructure.
Click here to get more info and download.
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.
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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:
Hurricane Sandy was the largest storm to ever originate in the Atlantic ocean. It badly damaged several countries in the Caribbean, caused over $50 billion in damages along the Eastern Seaboard, and left dozens dead. While hurricanes are a natural part of our climate system, research shows that intense hurricane activity has been on the rise in the North Atlantic since the 1970s. This trend is likely to be exacerbated by sea level rise and growing populations along coastlines. Natural coastal habitats — like wetlands and dunes — have proven to shield people from storms and sea-level rise, and have protected coastal communities from hundreds of millions of dollars in damage.
The Dunes at Shoal Harbor, a residential community in Monmouth County, New Jersey, is situated adjacent to both the Raritan Bay and the New York City Ferry channel. The site, previously utilized for industrial purposes, consisted of a partially demolished docking/berthing facility. A significantly undersized 6” diameter, 8-foot long stone revetment was also constructed on the property.
During Hurricane Sandy, the revetment failed and the community was subjected to direct wave attack and flooding. Homes were damaged, beach access was impaired, and the existing site-wide stormwater management basin and outfall was completely destroyed.
Princeton Hydro performed a wave attack analysis commensurate with a category three hurricane event, and used that data to complete a site design for shoreline protection. Consistent with the analysis, the site design includes the installation of a 15-foot rock revetment (one foot above the 100-year floodplain elevation) constructed with four-foot diameter boulders. The project also consists of replacing a failed elevated timber walkway with a concrete slab-on-grade walkway, restoring portions of the existing bulkhead, clearing invasive plants, and the complete restoration of the failed stormwater basin and outlet.
The plan incorporates natural barriers to reduce the impacts of storm surges and protect the coastal community, including planting stabilizing coastal vegetation to prevent erosion and installing fencing along the dune to facilitate natural dune growth.
These measures will discourage future erosion of the shoreline, protect the residential community from future wave attacks and flooding, and create a stable habitat for native and migratory species. The project is currently in the permitting phase, and will move to construction when all permits are obtained from local, state, and federal agencies.
This project is an great example of Princeton Hydro's ability to coordinate multi-disciplinary projects in-house. Our Water Resources Engineering, Geosciences Engineering, and Natural Resources teams have collaborated efficiently to analyze, design, and permit this shoreline protection project. For more information on our engineering services, go here.
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