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For over 150 years, migratory fish were unable to reach their breeding grounds upstream due to this structure. However, thanks to the efforts of the Buzzards Bay Coalition and its project partners, the dam was successfully removed between December 2019 and February 2021. As early as April 2021, migratory fish were seen swimming unimpeded from Buzzards Bay to lay their eggs in freshwater upstream. A true success story! This blog explores the Horseshoe Mill Dam removal project and celebrates the significant milestone in the recovery of fish populations and the restoration of ecological processes in the Weweantic River. A Brief History The Weweantic River winds its way through the picturesque landscapes of southeastern Massachusetts, spanning a length of 17.0 miles. This land is the traditional territory of the Wampanoag/Wôpanâak tribes. Derived from the Wampanoag language, Weweantic means "crooked" or "wandering stream." Originating from the wetlands in Carver, the river flows in a southerly direction meandering through swampy birch and maple forests in Middleborough and Rochester. Eventually, it empties into a Buzzards Bay estuary near the mouth of the Sippican River in Wareham. The river's watershed covers approximately 18,000 acres, with numerous cranberry bogs situated in its upper sections. Although the Weweantic River historically teemed with fish, the presence of the Horseshoe Mill Dam posed an obstacle to fish passage. The dam, spanning the Weweantic River at the head-of-tide, was built in 1827 to support a metal forge mill. Although it was once part of the infrastructure that supported Wareham’s economy, it had been decommissioned and left crumbling for decades. The defunct dam restricted to tidal inundation, hindered the migration of important fish species, and impacted riverine ecological processes. Ecological Importance of the Weweantic River The Weweantic River is the largest tributary to Buzzards Bay and provides 20 percent of all freshwater flow into Buzzards Bay. The meeting of salinity and nutrients through the tidal flow creates a vibrant ecosystem. It supports diverse communities of wetland species and a variety of non-migratory and migratory fish species, including river herring, white perch, and American eel. It is also home to the southernmost population of rainbow smelt in the United States, marking a significant change from a century ago when rainbow smelt were found as far south as the Chesapeake Bay. In the 1960s, smelt populations were even present in the Hudson River in New York. Further highlighting the ecological significance of the Weweantic River and its surrounding watershed are the unique tidal freshwater wetland plant communities. The wetland areas surrounding the Horseshoe Mill Dam site contained two rare wetland plants, Parker's Pipewort (Eriocaulon parkeri) and Pygmyweed (Crassula aquatica), both of which are designated as priority habitats for rare species. [gallery columns="2" size="medium" link="none" ids="14279,14281"] Additionally, situated along the shore of Buzzards Bay and the Weweantic River is the Cromeset Neck & Mark's Cove Marsh Wildlife Sanctuary. The 47-acre wildlife sanctuary consists of three separate parcels within one mile of each other. Salt marsh comprises most of the wildlife sanctuary, and the property also contains approximately six contiguous acres of coastal woodland. Restoration Efforts and Project Phases The Horseshoe Mill Dam removal project involved several phases to achieve its restoration goals. An inspection of the dam, conducted in 2009, rated its condition as unsatisfactory and noted significant concrete deterioration and erosion. The dam also included a former concrete-walled mill race that was in a state of disrepair, with collapsed walls and obstructed channels. The Buzzards Bay Coalition acquired the 10-acre Horseshoe Mill Dam property in 2012 to preserve it, provide public access, and pursue river restoration. In 2016, the Buzzards Bay Coalition contracted Princeton Hydro to provide an Alternatives Analysis for the Weweantic River restoration project and a Fish Passage Feasibility Study for the dam. The analysis included a thorough site investigation, historical data review, sediment evaluation, hydrologic and hydraulic analysis, and ecological assessment. The five options considered in the analysis were: No action; Structural dam repair with a fish ladder; Dam lowering with a nature-like fishway; Partial dam removal with an extended riffle; or Complete dam removal. The analysis ultimately helped the Buzzards Bay Coalition determine that a complete dam removal offered the most favorable ecological and economic outcomes. [caption id="attachment_12821" align="aligncenter" width="789"] The removal of Horseshoe Mill Dam commences on a snowy day in December 2019.[/caption] Princeton Hydro, contracted by the Buzzards Bay Coalition, provided site investigation, engineering design, permitting, and construction oversight services for the dam removal. With funding from the Bouchard 120 Natural Resource Damage Trustee Council and collaboration with various agencies, including the U.S. Fish and Wildlife Service and NOAA, the dam removal commenced in December 2019 and was successfully completed in early 2021. Just months later in April 2021, for the first time in 150+ years, migratory fish were once again spotted swimming unimpeded from Buzzards Bay to lay their eggs in freshwater upstream. Since the completion of the dam removal, Buzzards Bay Coalition Restoration Ecologist Sara da Silva Quintal has been consistently visiting the site and monitoring the positive changes taking place. Her observations include vegetation changes, signs of migratory fish spawning, and the geomorphic evolution of the landscape. She shared a series of Nearmap images that demonstrate how the landscape is positively adjusting to the barrier removal: Celebrating Conservation Success The completion of the Horseshoe Mill Dam removal project marks a significant achievement in the restoration of fish passage and the preservation of ecological function in the Weweantic River. Through the collaborative efforts of the Buzzards Bay Coalition, government agencies, and project partners, migratory fish can now freely swim upstream to their breeding grounds. The restoration effort rejuvenated more than three miles of the Weweantic River and restored migratory fish passage. The dam removal enhanced riverine, wetland, and tidal habitat critical to a diverse group of aquatic, wildlife and plant species. It allowed for the natural extension of upriver habitat for two rare tidal plant species, ensuring their long-term survival. The restoration work also enhanced public access to the area by increasing walking trails and constructing canoe/kayak launches, promoting recreational opportunities, and fostering a deeper connection between people and the river. [caption id="attachment_12824" align="aligncenter" width="710"] Photo taken on November 2022[/caption] In an article written by Kasey Silvia in November 2021, the Vice President for Watershed Protection at Buzzards Bay Coalition, Brendan Annett, was quoted as saying, “Removing this dam has immediately improved the natural functions of the Weweantic, undoing many years of environmental damage and it has already begun to bring the river back to life.” The success of this project serves as a testament to the importance of collaborative conservation efforts in safeguarding and restoring our natural resources. Princeton Hydro is a leader in dam removal in the Northeast, having designed and removed 80 dams. To view additional dam removal projects that we have completed, click here. For more information on our dam removal services, contact us here. [post_title] => Restoring Fish Passage and Ecological Function: The Horseshoe Mill Dam Removal Project [post_excerpt] => [post_status] => publish [comment_status] => open [ping_status] => open [post_password] => [post_name] => horseshoe-mill-dam-removal-project [to_ping] => [pinged] => [post_modified] => 2024-01-18 03:08:36 [post_modified_gmt] => 2024-01-18 03:08:36 [post_content_filtered] => [post_parent] => 0 [guid] => https://princetonhydro.com/?p=12814 [menu_order] => 0 [post_type] => post [post_mime_type] => [comment_count] => 0 [filter] => raw ) [1] => WP_Post Object ( [ID] => 2334 [post_author] => 3 [post_date] => 2018-08-15 12:07:45 [post_date_gmt] => 2018-08-15 12:07:45 [post_content] => Freshwater mussels are among the oldest living and second most diverse organisms on Earth with over 1,000 recognized species. Here in the eastern part of the U.S., we have more species of freshwater mussels than anywhere in the world. Unfortunately, freshwater mussels are one of the most rapidly declining animal groups in North America. Out of the 300 species and subspecies found on the continent, 70 (23%) have been federally listed as "Threatened" or "Endangered" under the Endangered Species Act. And, in the last century, over 30 species have become permanently extinct. So, why are populations declining so fast? Freshwater mussels are filter feeders and process large volumes of the water they live in to obtain food. This means of survival also makes them highly susceptible to industrial and agricultural water pollution. Because they are constantly filtering water, the contaminants and pathogens that are present are absorbed into the mussel’s tissues. As such, mussels are good indicators of water quality and can greatly contribute to improving water quality by filtering algae, bacteria and organic matter from the water column. Not only do freshwater mussels rely on water quality, they are dependent on fish and other aquatic organisms for reproductive success. In order for a freshwater mussel to complete the reproduction process, it must “infect” a host fish with its larvae. The method depends on the specie of mussel. Some species lure fish using highly modified and evolved appendages that mimic prey. When a fish goes into investigate the lures, the female mussel releases fertilized eggs that attach to the fish, becoming temporarily parasitic. Once the host fish is infected, it can transfer the mussel larvae upstream and into new areas of the river. Both habitat loss from dam construction and the introduction of pesticides into the water supply has contributed to the decline of freshwater mussels. With approximately 300 mussel species in the U.S. alone, a critical component of restoring and revitalizing mussel populations is truly understanding their biology, which begins with the ability to properly differentiate each species and properly identify and catalog them. Princeton Hydro’s Senior Scientist Evan Kwityn, CLP and Aquatic Ecologist Jesse Smith recently completed the U.S. Fish and Wildlife Service's Fresh Water Mussel Identification Training at the National Conservation Training Center in West Virginia. Through hands-on laboratory training, Evan and Jesse developed their freshwater mussel identification skills and their knowledge of freshwater mussel species biology. Course participants were tasked with mastering approximately 100 of the most common freshwater mussel species in the United States. They also learned about proper freshwater mussel collection labeling, the internal and external anatomy and meristics of a freshwater mussel, and distributional maps as an aid to freshwater mussel identification. In a recently published press release, Tierra Curry, a senior scientist with the Center for Biological Diversity was quoted as saying, “The health of freshwater mussels directly reflects river health, so protecting the places where these mussels live will help all of us who rely on clean water. This is especially important now, when we see growing threats to clean water from climate change, agriculture and other sources.” Princeton Hydro is committed to protecting water quality, restoring habitats, and managing natural resources. Read about some of our recent projects and contact us to discuss how we can help you. To learn more about freshwater mussels, check out this video from U.S. Fish and Wildlife Service: [embed]https://youtu.be/OWjlwfx67eY?si=YLCmgt2Ry0GiQ6BQ[/embed] [visual-link-preview encoded="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"] … [post_title] => Restoring and Revitalizing Freshwater Mussels [post_excerpt] => [post_status] => publish [comment_status] => open [ping_status] => open [post_password] => [post_name] => freshwater-mussels [to_ping] => [pinged] => [post_modified] => 2025-11-04 02:21:08 [post_modified_gmt] => 2025-11-04 02:21:08 [post_content_filtered] => [post_parent] => 0 [guid] => http://www.princetonhydro.com/blog/?p=2334 [menu_order] => 0 [post_type] => post [post_mime_type] => [comment_count] => 0 [filter] => raw ) ) [post_count] => 2 [current_post] => -1 [before_loop] => 1 [in_the_loop] => [post] => WP_Post Object ( [ID] => 12814 [post_author] => 1 [post_date] => 2023-06-12 17:15:54 [post_date_gmt] => 2023-06-12 17:15:54 [post_content] => The Horseshoe Mill Dam, built in 1827, served as the first barrier to fish passage on the Weweantic River in Wareham, Massachusetts. For over 150 years, migratory fish were unable to reach their breeding grounds upstream due to this structure. However, thanks to the efforts of the Buzzards Bay Coalition and its project partners, the dam was successfully removed between December 2019 and February 2021. As early as April 2021, migratory fish were seen swimming unimpeded from Buzzards Bay to lay their eggs in freshwater upstream. A true success story! This blog explores the Horseshoe Mill Dam removal project and celebrates the significant milestone in the recovery of fish populations and the restoration of ecological processes in the Weweantic River. A Brief History The Weweantic River winds its way through the picturesque landscapes of southeastern Massachusetts, spanning a length of 17.0 miles. This land is the traditional territory of the Wampanoag/Wôpanâak tribes. Derived from the Wampanoag language, Weweantic means "crooked" or "wandering stream." Originating from the wetlands in Carver, the river flows in a southerly direction meandering through swampy birch and maple forests in Middleborough and Rochester. Eventually, it empties into a Buzzards Bay estuary near the mouth of the Sippican River in Wareham. The river's watershed covers approximately 18,000 acres, with numerous cranberry bogs situated in its upper sections. Although the Weweantic River historically teemed with fish, the presence of the Horseshoe Mill Dam posed an obstacle to fish passage. The dam, spanning the Weweantic River at the head-of-tide, was built in 1827 to support a metal forge mill. Although it was once part of the infrastructure that supported Wareham’s economy, it had been decommissioned and left crumbling for decades. The defunct dam restricted to tidal inundation, hindered the migration of important fish species, and impacted riverine ecological processes. Ecological Importance of the Weweantic River The Weweantic River is the largest tributary to Buzzards Bay and provides 20 percent of all freshwater flow into Buzzards Bay. The meeting of salinity and nutrients through the tidal flow creates a vibrant ecosystem. It supports diverse communities of wetland species and a variety of non-migratory and migratory fish species, including river herring, white perch, and American eel. It is also home to the southernmost population of rainbow smelt in the United States, marking a significant change from a century ago when rainbow smelt were found as far south as the Chesapeake Bay. In the 1960s, smelt populations were even present in the Hudson River in New York. Further highlighting the ecological significance of the Weweantic River and its surrounding watershed are the unique tidal freshwater wetland plant communities. The wetland areas surrounding the Horseshoe Mill Dam site contained two rare wetland plants, Parker's Pipewort (Eriocaulon parkeri) and Pygmyweed (Crassula aquatica), both of which are designated as priority habitats for rare species. [gallery columns="2" size="medium" link="none" ids="14279,14281"] Additionally, situated along the shore of Buzzards Bay and the Weweantic River is the Cromeset Neck & Mark's Cove Marsh Wildlife Sanctuary. The 47-acre wildlife sanctuary consists of three separate parcels within one mile of each other. Salt marsh comprises most of the wildlife sanctuary, and the property also contains approximately six contiguous acres of coastal woodland. Restoration Efforts and Project Phases The Horseshoe Mill Dam removal project involved several phases to achieve its restoration goals. An inspection of the dam, conducted in 2009, rated its condition as unsatisfactory and noted significant concrete deterioration and erosion. The dam also included a former concrete-walled mill race that was in a state of disrepair, with collapsed walls and obstructed channels. The Buzzards Bay Coalition acquired the 10-acre Horseshoe Mill Dam property in 2012 to preserve it, provide public access, and pursue river restoration. In 2016, the Buzzards Bay Coalition contracted Princeton Hydro to provide an Alternatives Analysis for the Weweantic River restoration project and a Fish Passage Feasibility Study for the dam. The analysis included a thorough site investigation, historical data review, sediment evaluation, hydrologic and hydraulic analysis, and ecological assessment. The five options considered in the analysis were: No action; Structural dam repair with a fish ladder; Dam lowering with a nature-like fishway; Partial dam removal with an extended riffle; or Complete dam removal. The analysis ultimately helped the Buzzards Bay Coalition determine that a complete dam removal offered the most favorable ecological and economic outcomes. [caption id="attachment_12821" align="aligncenter" width="789"] The removal of Horseshoe Mill Dam commences on a snowy day in December 2019.[/caption] Princeton Hydro, contracted by the Buzzards Bay Coalition, provided site investigation, engineering design, permitting, and construction oversight services for the dam removal. With funding from the Bouchard 120 Natural Resource Damage Trustee Council and collaboration with various agencies, including the U.S. Fish and Wildlife Service and NOAA, the dam removal commenced in December 2019 and was successfully completed in early 2021. Just months later in April 2021, for the first time in 150+ years, migratory fish were once again spotted swimming unimpeded from Buzzards Bay to lay their eggs in freshwater upstream. Since the completion of the dam removal, Buzzards Bay Coalition Restoration Ecologist Sara da Silva Quintal has been consistently visiting the site and monitoring the positive changes taking place. Her observations include vegetation changes, signs of migratory fish spawning, and the geomorphic evolution of the landscape. She shared a series of Nearmap images that demonstrate how the landscape is positively adjusting to the barrier removal: Celebrating Conservation Success The completion of the Horseshoe Mill Dam removal project marks a significant achievement in the restoration of fish passage and the preservation of ecological function in the Weweantic River. Through the collaborative efforts of the Buzzards Bay Coalition, government agencies, and project partners, migratory fish can now freely swim upstream to their breeding grounds. The restoration effort rejuvenated more than three miles of the Weweantic River and restored migratory fish passage. The dam removal enhanced riverine, wetland, and tidal habitat critical to a diverse group of aquatic, wildlife and plant species. It allowed for the natural extension of upriver habitat for two rare tidal plant species, ensuring their long-term survival. The restoration work also enhanced public access to the area by increasing walking trails and constructing canoe/kayak launches, promoting recreational opportunities, and fostering a deeper connection between people and the river. [caption id="attachment_12824" align="aligncenter" width="710"] Photo taken on November 2022[/caption] In an article written by Kasey Silvia in November 2021, the Vice President for Watershed Protection at Buzzards Bay Coalition, Brendan Annett, was quoted as saying, “Removing this dam has immediately improved the natural functions of the Weweantic, undoing many years of environmental damage and it has already begun to bring the river back to life.” The success of this project serves as a testament to the importance of collaborative conservation efforts in safeguarding and restoring our natural resources. Princeton Hydro is a leader in dam removal in the Northeast, having designed and removed 80 dams. To view additional dam removal projects that we have completed, click here. For more information on our dam removal services, contact us here. 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The Horseshoe Mill Dam, built in 1827, served as the first barrier to fish passage on the Weweantic River in Wareham, Massachusetts. For over 150 years, migratory fish were unable to reach their breeding grounds upstream due to this structure. However, thanks to the efforts of the Buzzards Bay Coalition and its project partners, the dam was successfully removed between December 2019 and February 2021. As early as April 2021, migratory fish were seen swimming unimpeded from Buzzards Bay to lay their eggs in freshwater upstream. A true success story!
This blog explores the Horseshoe Mill Dam removal project and celebrates the significant milestone in the recovery of fish populations and the restoration of ecological processes in the Weweantic River.
The Weweantic River winds its way through the picturesque landscapes of southeastern Massachusetts, spanning a length of 17.0 miles. This land is the traditional territory of the Wampanoag/Wôpanâak tribes. Derived from the Wampanoag language, Weweantic means "crooked" or "wandering stream."
Originating from the wetlands in Carver, the river flows in a southerly direction meandering through swampy birch and maple forests in Middleborough and Rochester. Eventually, it empties into a Buzzards Bay estuary near the mouth of the Sippican River in Wareham. The river's watershed covers approximately 18,000 acres, with numerous cranberry bogs situated in its upper sections.
Although the Weweantic River historically teemed with fish, the presence of the Horseshoe Mill Dam posed an obstacle to fish passage. The dam, spanning the Weweantic River at the head-of-tide, was built in 1827 to support a metal forge mill. Although it was once part of the infrastructure that supported Wareham’s economy, it had been decommissioned and left crumbling for decades. The defunct dam restricted to tidal inundation, hindered the migration of important fish species, and impacted riverine ecological processes.
The Weweantic River is the largest tributary to Buzzards Bay and provides 20 percent of all freshwater flow into Buzzards Bay. The meeting of salinity and nutrients through the tidal flow creates a vibrant ecosystem. It supports diverse communities of wetland species and a variety of non-migratory and migratory fish species, including river herring, white perch, and American eel. It is also home to the southernmost population of rainbow smelt in the United States, marking a significant change from a century ago when rainbow smelt were found as far south as the Chesapeake Bay. In the 1960s, smelt populations were even present in the Hudson River in New York.
Further highlighting the ecological significance of the Weweantic River and its surrounding watershed are the unique tidal freshwater wetland plant communities. The wetland areas surrounding the Horseshoe Mill Dam site contained two rare wetland plants, Parker's Pipewort (Eriocaulon parkeri) and Pygmyweed (Crassula aquatica), both of which are designated as priority habitats for rare species.
Additionally, situated along the shore of Buzzards Bay and the Weweantic River is the Cromeset Neck & Mark's Cove Marsh Wildlife Sanctuary. The 47-acre wildlife sanctuary consists of three separate parcels within one mile of each other. Salt marsh comprises most of the wildlife sanctuary, and the property also contains approximately six contiguous acres of coastal woodland.
The Horseshoe Mill Dam removal project involved several phases to achieve its restoration goals.
An inspection of the dam, conducted in 2009, rated its condition as unsatisfactory and noted significant concrete deterioration and erosion. The dam also included a former concrete-walled mill race that was in a state of disrepair, with collapsed walls and obstructed channels. The Buzzards Bay Coalition acquired the 10-acre Horseshoe Mill Dam property in 2012 to preserve it, provide public access, and pursue river restoration.
In 2016, the Buzzards Bay Coalition contracted Princeton Hydro to provide an Alternatives Analysis for the Weweantic River restoration project and a Fish Passage Feasibility Study for the dam. The analysis included a thorough site investigation, historical data review, sediment evaluation, hydrologic and hydraulic analysis, and ecological assessment. The five options considered in the analysis were:
The analysis ultimately helped the Buzzards Bay Coalition determine that a complete dam removal offered the most favorable ecological and economic outcomes.
Princeton Hydro, contracted by the Buzzards Bay Coalition, provided site investigation, engineering design, permitting, and construction oversight services for the dam removal. With funding from the Bouchard 120 Natural Resource Damage Trustee Council and collaboration with various agencies, including the U.S. Fish and Wildlife Service and NOAA, the dam removal commenced in December 2019 and was successfully completed in early 2021. Just months later in April 2021, for the first time in 150+ years, migratory fish were once again spotted swimming unimpeded from Buzzards Bay to lay their eggs in freshwater upstream.
Since the completion of the dam removal, Buzzards Bay Coalition Restoration Ecologist Sara da Silva Quintal has been consistently visiting the site and monitoring the positive changes taking place. Her observations include vegetation changes, signs of migratory fish spawning, and the geomorphic evolution of the landscape. She shared a series of Nearmap images that demonstrate how the landscape is positively adjusting to the barrier removal:
The completion of the Horseshoe Mill Dam removal project marks a significant achievement in the restoration of fish passage and the preservation of ecological function in the Weweantic River. Through the collaborative efforts of the Buzzards Bay Coalition, government agencies, and project partners, migratory fish can now freely swim upstream to their breeding grounds.
The restoration effort rejuvenated more than three miles of the Weweantic River and restored migratory fish passage. The dam removal enhanced riverine, wetland, and tidal habitat critical to a diverse group of aquatic, wildlife and plant species. It allowed for the natural extension of upriver habitat for two rare tidal plant species, ensuring their long-term survival. The restoration work also enhanced public access to the area by increasing walking trails and constructing canoe/kayak launches, promoting recreational opportunities, and fostering a deeper connection between people and the river.
In an article written by Kasey Silvia in November 2021, the Vice President for Watershed Protection at Buzzards Bay Coalition, Brendan Annett, was quoted as saying, “Removing this dam has immediately improved the natural functions of the Weweantic, undoing many years of environmental damage and it has already begun to bring the river back to life.”
The success of this project serves as a testament to the importance of collaborative conservation efforts in safeguarding and restoring our natural resources.
Freshwater mussels are among the oldest living and second most diverse organisms on Earth with over 1,000 recognized species. Here in the eastern part of the U.S., we have more species of freshwater mussels than anywhere in the world. Unfortunately, freshwater mussels are one of the most rapidly declining animal groups in North America. Out of the 300 species and subspecies found on the continent, 70 (23%) have been federally listed as "Threatened" or "Endangered" under the Endangered Species Act. And, in the last century, over 30 species have become permanently extinct. So, why are populations declining so fast?
Freshwater mussels are filter feeders and process large volumes of the water they live in to obtain food. This means of survival also makes them highly susceptible to industrial and agricultural water pollution. Because they are constantly filtering water, the contaminants and pathogens that are present are absorbed into the mussel’s tissues. As such, mussels are good indicators of water quality and can greatly contribute to improving water quality by filtering algae, bacteria and organic matter from the water column.
Not only do freshwater mussels rely on water quality, they are dependent on fish and other aquatic organisms for reproductive success. In order for a freshwater mussel to complete the reproduction process, it must “infect” a host fish with its larvae. The method depends on the specie of mussel. Some species lure fish using highly modified and evolved appendages that mimic prey. When a fish goes into investigate the lures, the female mussel releases fertilized eggs that attach to the fish, becoming temporarily parasitic. Once the host fish is infected, it can transfer the mussel larvae upstream and into new areas of the river.
Both habitat loss from dam construction and the introduction of pesticides into the water supply has contributed to the decline of freshwater mussels. With approximately 300 mussel species in the U.S. alone, a critical component of restoring and revitalizing mussel populations is truly understanding their biology, which begins with the ability to properly differentiate each species and properly identify and catalog them. Princeton Hydro’s Senior Scientist Evan Kwityn, CLP and Aquatic Ecologist Jesse Smith recently completed the U.S. Fish and Wildlife Service's Fresh Water Mussel Identification Training at the National Conservation Training Center in West Virginia.
Through hands-on laboratory training, Evan and Jesse developed their freshwater mussel identification skills and their knowledge of freshwater mussel species biology. Course participants were tasked with mastering approximately 100 of the most common freshwater mussel species in the United States. They also learned about proper freshwater mussel collection labeling, the internal and external anatomy and meristics of a freshwater mussel, and distributional maps as an aid to freshwater mussel identification.
In a recently published press release, Tierra Curry, a senior scientist with the Center for Biological Diversity was quoted as saying, “The health of freshwater mussels directly reflects river health, so protecting the places where these mussels live will help all of us who rely on clean water. This is especially important now, when we see growing threats to clean water from climate change, agriculture and other sources.”
Princeton Hydro is committed to protecting water quality, restoring habitats, and managing natural resources. Read about some of our recent projects and contact us to discuss how we can help you.
To learn more about freshwater mussels, check out this video from U.S. Fish and Wildlife Service:
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