Enjoy Your Labor Day Adventures Responsibly

Princeton Hydro Offers
Seven Tips for Environmentally-Friendly Outdoor Fun


Labor Day is right around the corner! Many people will soon be packing up the car with fishing gear, and heading to their favorite lake for a fun-filled weekend.

As biologists, scientists and outdoor enthusiasts, all of us at Princeton Hydro fully enjoy getting outside and having fun in nature. We also take our responsibility to care for and respect our natural surroundings very seriously. We play hard and work hard to protect our natural resources for generations to come.

These seven tips will help you enjoy your Labor Day fishing, boating and outdoor adventures with minimal environmental impact:

  • Before you go, know your local fishing regulations. These laws protect fish and other aquatic species to ensure that the joys of fishing can be shared by everyone well into the future.
  • Reduce the spread of invasive species by thoroughly washing your gear and watercraft before and after your trip. Invasives come in many forms – plants, fungi and animals – and even those of microscopic size can cause major damage.
  • Stay on designated paths to avoid disrupting sensitive and protected areas, like wetlands, shorelines, stream banks and meadows. Disturbing and damaging these sensitive areas can jeopardize the health of the many important species living there.
  • Exercise catch and release best practices. Always keep the health of the fish at the forefront of your activities by using the right gear and employing proper techniques. Get that info by clicking here
  • Use artificial lures or bait that is native to the area you’re fishing in. Live bait that is non-native can introduce invasive species to water sources and cause serious damage to the surrounding environment.
  • Plan ahead and map your trip. Contact the office of land management to learn about permit requirements, area closures and other restrictions. Use this interactive map to find great fishing spots in your area, the fish species you can expect to find at each spot, nearby gear shops, and more!

Armed with these seven tips, you can now enjoy your weekend while feeling rest assured that you’re doing your part to protect the outdoor spaces and wild places we all love to recreate in! Go here to learn about some of the work Princeton Hydro does to restore and protect our natural resources.

120903 Dock
“Respect nature and it will provide you with abundance.”


Deal Lake Improves Water Quality on a Sustainable Basis

Success Spotlight: Deal Lake Watershed Protection Plan Implementation Project

Deal Lake Commission, Interlaken, New Jersey

Deal Lake is the largest of New Jersey’s coastal lakes, encompassing 155 acres and spanning over 27 miles of shoreline. The lake’s 4,400-acre watershed is highly developed, with the majority of development dating back to the 1940s-1960s. As a result, stormwater management, particularly with respect to water quality and volume management, is largely lacking.

Since 1980, the Deal Lake Commission (DLC) has served as the State-appointed steward of the lake.  Princeton Hydro secured the DLC $450,000 in 319(h) funding to implement the lake’s New Jersey Department of Environmental Protection-approved Watershed Protection Plan. The 319(h) funding was used by the DLC to conduct three projects designed to decrease stormwater-based pollutant loading, improve the lake’s water quality, and restore heavily eroded sections of the shoreline.

Asbury Park Comstock Street MTD

Screen Shot 2016-05-23 at 9.20.04 AMThis project involved the installation of a manufactured treatment device (MTD). MTDs are very effective “retrofit” solutions that can be used to address stormwater issues even in highly developed areas. The MTD installation was complicated by site constraints including sub-surface infrastructure. Post-installation field testing and STEPL modeling conducted by Princeton Hydro confirmed that the MTD significantly decreased the pollutant loading from one of the lake’s major stormwater outfalls.


Colonial Terrace Golf Course Bioretention BMPs
Screen Shot 2016-05-23 at 9.25.17 AM

Princeton Hydro conducted the field testing, engineering design, and permitting of three bio-infiltration basins constructed at the Colonial Terrace Golf Course (CTGC). Post-project-completion field testing showed each basin is capable of fully infiltrating the runoff generated by storms as great as 1.5 inches per hour. In addition, over 300 feet of eroded shoreline was stabilized with native plants. Doing so helped create a dense buffer that inhibits passage of Canada geese from the lake onto the golf course.


Asbury Park Boat Launch Shoreline Stabilization

Princeton Hydro developed a bio-engineering design for the stabilization of a badly eroded 250-foot segment section of shoreline adjacent to the Asbury Park boat launch. Coir fiber logs were used in conjunction with native plant material. As with the CTGC planting, help was provided by local volunteers and the DLC commissioners. The final element of the project involved the construction of a bioretention rain garden to control the runoff from the boat launch parking area. Signage was also installed to inform the public about the project and the benefits of shoreline naturalization.


The Deal Lake Watershed Protection Plan Implementation Project proved that despite Deal Lake being located in a highly urbanized watershed, it is possible to implement cost-effective green infrastructure and stormwater retrofit solutions capable of significantly decreasing pollutant loading to the lake.  These measures are part of the DLC’s continued efforts to utilize environmentally sustainable techniques to improve the lake’s water quality. This project won a North American Lake Management Society Technical Merit Award.

For more information about this and other Princeton Hydro projects, please contact us!

Pesticide-Free Lake Management Solutions

Blue Water Solutions for Green Water Problems

Managing your lakes and ponds without the use of pesticides


Proper lake and pond restoration is contingent with having a well prepared management plan. If you don’t start there, you’re just guessing as to which solutions will solve your problem. Successful, sustainable lake and pond management requires identifying and correcting the cause of eutrophication as opposed to simply reacting to the symptoms (algae and weed growth) of eutrophication. As such, Princeton Hydro collects and analyzes data to identify the problem causers and uses these scientific findings to develop a customized management plan for your specific lake or pond. A successful management plan should include a combination of biological, mechanical and source control solutions.  Here are some examples:

Biological Control:

Floating Wetland Islands (FWIs) are a great example of an effective biological control solution. They have the potential to provide multiple ecological benefits. Highly adaptable, FWIs can be sized, configured and planted to fit the needs of nearly any lake, pond or reservoir.


Often described as self-sustaining, Floating Wetland Islands:

  • Help assimilate and remove excess nutrients that could fuel algae growth
  • Provide habitat for fish and other aquatic organisms
  • Help mitigate wave and wind erosion impacts
  • Provide an aesthetic element
  • Can be part of a holistic lake/pond management strategy

Read an article on Floating Wetland Islands written by our Aquatics Director Fred Lubnow.

Mechanical Control:

Another way to combat algae and invasive weed growth is via mechanical removal. One of the mechanical controls Princeton Hydro employs is the TruxorDM5000, an eco-friendly, multi-purpose amphibious machine that provides an effective, non-pesticide approach to controlling invasive weeds and problematic algae growth.

The TruxorDM5000: TRUXOR

  • Is capable of operating in shallow ponds and lakes where the access and/or operation of conventional harvesting or hydroraking equipment is limited
  • Is highly portable and maneuverable, yet very powerful
  • Can cut and harvest weeds and collect mat algae in near-shore areas with water depths less than three feet
  • Includes various attachments that allow the machine to easily collect and remove a variety of debris
  • Can be outfitted for sediment removal/dredging

Check out the Truxor in action here! 

Source Control:

Because phosphorus is typically the nutrient that fuels algae and weed growth, excessive phosphorus loading leads to problematic algal blooms and can stimulate excessive weed growth. One of the most sustainable means of controlling nuisance weed and algae proliferation is to control phosphorus inputs or reduce the availability of phosphorus for biological uptake and assimilation. The measures that decrease the amount or availability of phosphorus in a lake or pond are defined as “source control” strategies.

Deerfield Lake, PA – PhosLockTM treatment Through data collection and analysis, we can properly identify the primary sources of phosphorus loading to a lake and pond, whether those sources are internal or external.  Our team of lake managers, aquatic ecologists and water resource engineers use those data to develop a management plan that quantifies, prioritizes and correctly addresses problem sources of phosphorus.

PhosLockTM and alum are often utilized as environmentally-safe and controlled means to limit phosphorus availably. Although PhosLockTM works similar to alum, it does not have some of the inherent secondary environmental limitations associated with alum. PhosLockTM is a patented product that has a high affinity to bind to and permanently remove from the water column both soluble reactive and particulate forms of phosphorus. This makes it a very effective pond and lake management tool.

Read more about controlling harmful algae blooms.

These are just a few of the examples of non-pesticide lake and pond management strategies that Princeton Hydro regularly utilizes. Properly managing your lakes and ponds starts with developing the right plan and involves a holistic approach to ensure continued success. For more ideas or for help putting together a customized, comprehensive management plan, please contact us! 

How to Improve Water Quality in Your Community

Simple steps lead to big leaps in protecting water quality!
Clean water is essential to the health of communities everywhere! Here are eight things you can do to protect water resources in your community and beyond:
  • Stop mowing near streams and pondsMowing near streams and ponds eliminates the natural protective buffer that tall grasses, shrubs and trees provide. Natural buffers protect against erosion, filter stormwater runoff, reduce harmful pollutant loads and provide habitat for mosquito-eating amphibians, fish, birds and beneficial insects.
  • Reduce lawn fertilizer usage: One of the best ways to support the health of local water resources is to reduce the use of pesticides and fertilizers. Not only are they costly, but, when over-applied or if applied right before a rainstorm, the chemicals runoff directly into our local waterways. Before applying, always remember to test your soil, read product labels and check the forecast. Also consider natural alternatives like composting!
  • Host a “Test Your Well” event: Well testing is a great way to promote groundwater protection, help people understand their role in safeguarding drinking water quality, and provide education around the proper disposal of oil, chemicals, pesticides and medicines. Learn how to host an event in your community!
  • Design and construct a rain garden: You’ve heard this one from us before, but, what can we say, we love rain gardens, and rightfully so! They’re cost effective, easy to build and do wonders in reducing erosion, promoting ground water recharge, minimizing flooding and removing pollutants from stormwater runoff. Read all about them!
  • Test and treat your ponds and lakes: Testing your pond/lake water is an important part of preventing problems like harmful weed and algae growth. Princeton Hydro professionals can provide a comprehensive analysis and an array of eco-friendly approaches to control nuisance species and promote the continual health of your pond/lake. Learn more!
  • Reduce erosion and exposed soil on your property: If you notice erosion occurring on your property, planting native plants can really help! Their roots stabilize the soil, reduce erosion and prevent sediment loading in your waterways, which has a huge impact on the water quality of downstream ponds, lakes and reservoirs!
  • Develop a stewardship plan for your community: Bring your community together to help preserve its natural resources. Princeton Hydro’s team of natural resource scientists can help you get the ball rolling by preparing stewardship plans focused on controlling invasive species and protecting the long-term health of open spaces, forests habitats, wetlands and water-quality in your community.
Contact us to discuss how Princeton Hydro can help you protect your local water resources and keep your community healthy for future generations! 
“Water is life, and clean water means health.”
Audrey Hepburn

7 Easy Water Conservation Tips

Spring is Here!

What better time to “spring” into water conservation?!

Here are a few simple ways to incorporate water conservation into your spring-cleaning routine:

  • Household leaks can waste more than 1 trillion gallons annually nationwide. Spring is a great time to check for leaks, some of which may have have been caused by winter freeze. Check garden hose spigots, sprinklers, faucets, showers and toilets for leaks, and replace valves, washers and other components as necessary.
  • Install a low-flow showerhead; doing so can save you up to 75 gallons of water per week.
  • While planning your spring/summer flower garden, be sure to incorporate water-wise garden techniques that include drought tolerant plants native to your area. Click here for more info!
  • Create a rain garden! Prepare for spring showers by constructing rain gardens into which runoff from downspouts, walkways, parking areas and even lawn surfaces can be directed. Rain gardens are an inexpensive, attractive and sustainable means to minimize runoff. Click here to learn more!
  • Install a rain barrel and use the captured rainfall to irrigate flower beds. This is another fun and inexpensive way to reduce runoff and save water.
  • To decrease irrigation demands, reduce the size of your lawn (see above tips) and switch to drought tolerant grass species. Also, delay regular lawn watering during cooler spring weather, and irrigate deep, but less frequently during the summer to encourage deep root growth. These measures ensure a healthier lawn throughout the summer. During the summer, keep your mower height high and don’t cut off more than one third of the grass blades; this promotes a healthy lawn that is more drought tolerant.
  • When cleaning your driveway, sidewalk and patio areas, remember to use a broom, not a hose. This not only helps conserve water, it also prevents the run-off of pollutants into our storm drains and ultimately our lakes, ponds, streams, rivers and oceans.
“Spring” into water conservation
and make it a part of every season!

Preventing Zika Virus & Other Mosquito-Borne Diseases

The start of mosquito season is right around the corner. Princeton Hydro offers simple solutions to reduce mosquito exposure and eliminate mosquito breeding.

Concerns about Zika virus (transmitted by the Aedes aegypti mosquito) arose in Brazil last May and have since quickly escalated. With cases confirmed in over 20 countries across Central and South America, the World Health Organization (WHO) recently declared the virus an international public health emergency. WHO reported that Zika could infect as many as 4 million people by the end of 2016. Additionally, West Nile virus remains a concern throughout the U.S. along with other mosquito-borne illnesses that affect humans, pets and livestock.

With spring rains and warmer temperatures on the horizon, mosquitos of all types will soon be buzzing. As predicted by the National Center for Atmospheric Research, by June we can expect mosquitos carrying the Zika virus to arrive in the Mid-Atlantic States. There are many simple measures that public and private pond and land owners can take in advance of mosquito season to reduce mosquito breeding and lessen the spread of mosquito-borne illnesses without resorting to the use of chemicals.

Here are three simple mosquito-prevention tips for ponds:

  • Eliminate stagnant water by installing a sub-surface aeration system. This will keep the pond thoroughly mixed and properly circulated. Subsurface aeration systems are the most cost-effective and energy-efficient way to maintain proper pond circulation and mixing. DSC02027Agitating the water’s surface interferes with the female mosquito’s ability to lay eggs and the success of mosquito larvae.
  • Along the shoreline of the pond, maintain or create an aquascaped edge dominated by native, non-invasive vegetation. As opposed to a sterile lawn edge, an aquascaped edge provides habitat for mosquito-eating amphibians, fish, birds, and beneficial insects.
  • Prevent grass clippings and lawn fertilizer from entering the pond. Doing so decreases the chance of an algae bloom which could create the still water conditions that favor mosquito breeding.

Additionally, you may want to consider hiring a certified professional to assess your pond and develop a customized management plan. Having your pond inspected by an expert helps you stay informed about your pond’s ecological status and implement measures to prevent/remedy conditions that could create mosquito breeding habitat and promote mosquito related problems.

But that’s not all!

Here are seven things you can do around your home or business property to prevent mosquito breeding:

  • Stagnant water is the perfect habitat for mosquito breeding. IMG_0695Check your property for areas where water easily collects: empty flower pots, buckets, old tires, tire ruts, low spots in lawns and trash cans.
  • Clear clogged rain gutters and storm drains, and keep them free of debris.
  • Regularly change the water in bird baths and pet dishes.
  • Store canoes and small boats upside-down.
  • Check tarps and grill covers for pooled water, and shake them out after a rain storm.
  • Repair leaky outside faucets, pipes and hoses to prevent puddles from forming.

Simply put, if you want to limit mosquito breeding in your pond or on your property, take the time to implement long-term management measures that integrate natural solutions, thereby creating an inhospitable environment for mosquitos. As noted above, this can be accomplished without resorting to chemicals! In addition to keeping your pond properly circulated, employ preventative practices that eliminate potential mosquito-breeding areas around your property, and regularly inspect areas to help quickly identify and resolve developing mosquito populations.

Princeton Hydro offers a full complement of services, including detailed water quality analysis, adaptive management plans and field services covering all areas of pond maintenance. Our team of certified lake and pond managers, wetland scientists, and water resource engineers can provide you with the expertise needed to diagnose the cause of pond problems and develop solutions that are environmentally sound and cost-effective. Contact Princeton Hydro to discuss how we can help you!

Read an interesting article about the origins of Zika here.

Visit Princeton Hydro at PALMS Conference: February 24 & 25

The Pennsylvania Lake Management Society (PALMS) is hosting its 26th annual conference on February 24 & 25 at the Ramada Hotel and Conference Center in State College, PA. Lake professionals, students, recreation enthusiasts, lakeside residents and community members are all invited to come together to explore a variety of topics related to managing lakes and reservoirs. 

The conference offers a collection of professional presentations, workshops and panel discussions. Attendees are also invited to the exhibit hall to discover the latest lake management tools and technologies, exchange information with a diverse group of vendors and network with peers. Be sure to visit the Princeton Hydro Booth to talk with them about the latest advancements in pond, lake and watershed management.

On February 24, Princeton Hydro President, Stephen Souza, invites you to attend his presentation on tracking and controlling cyanobacteria (blue-green algae) blooms using the firm’s unique PARE™ program. The presentation is at 11:10am followed by a panel discussion on cyanobacteria related lake and pond issues at 11:50am.

During the second day of the conference, Princeton Hydro Director of Aquatic Programs, Fred Lubnow, encourages you to join him for a lecture and discussion on the ecology and management of shallow lakes at 11:30am. 

Click here for the complete 2016 PALMS Conference Schedule. The Princeton Hydro team hopes to see you there! 

In advance of the conference, if you’d like to learn more about the problems associated with cyanobacteria (blue-green algae) blooms and how to implement PARE™, a comprehensive program for tracking and quantifying harmful algae blooms, you can read the “Emerging Issues” white paper by clicking here.

Natural Flow Regime and Ecological Integrity

In July 2013, the United States Geological Survey[1] (USGS) released CircularEcological Health in the Nation’s Streams, 1993—2005 1391 titled, “The Quality of our Nation’s Waters – Ecological Health in the Nation’s Streams, 1993-2005”.  Circular 1391 reported the approach and findings of multiple community assessments conducted in streams throughout the US.  Based on its application of integrated biological assessment (i.e., combined analysis of algae, macroinvertebrate, and fish communities), USGS concluded that at least one among these three biological communities was altered[2] in 83% of the assessed streams; while all three biological communities were altered in 22% of the streams considered.  The biological impairment USGS catalogued range from 79% in agricultural settings to 89% in urban settings.  A biological community was deemed unaltered in just 17% of the assessed streams.

By coincidence, in July 2013 Princeton Hydro, LLC completed, “The Monponsett Pond and Silver Lake Water Use Operations and Improvement Report”.  Princeton Hydro’s report, prepared on behalf of the Town of Halifax in Plymouth County, Massachusetts; was funded by a competitive grant program – the Massachusetts Sustainable Water Management Initiative (SWMI).  The overall principle of SWMI is stated as:SWMI Report cover

The Commonwealth’s water resources are public resources that require sustainable management practices for the well-being and safety of our citizens, protection of the natural environment, and for economic growth.

The central issue for us to consider was an archaic water management circumstance, established through an 1899 State legislative Act and further complicated by two crisis management episodes in the 1960s and 1980s, respectively; that authorized the City of Brockton, MA to source the majority of its municipal water supplies from three water bodies (Silver Lake, Monponsett Pond, and Furnace Pond) located near Halifax, MA.  Brockton is situated 20 miles northwest of its Silver Lake Water Treatment Plant (WTP).  Moreover, Silver Lake, Monponsett Pond, and Furnace Pond each lie in the headwaters of different watersheds.

Princeton Hydro’s Role: Review and Analysis of the Brockton Water Supply System

In December 2012, Princeton Hydro was asked by the Monponsett Watershed Association (MWA) and the Jones River Watershed Association (JRWA) to act as technical lead for a bid by the Town of Halifax seeking SWMI grant funding.  MPWA and JRWA viewed Princeton Hydro as an ideal partner for this project owing to our diverse skills and expertise in water resource management.  Moreover, although we work in a variety of settings throughout Massachusetts, as a geographic outsider, Princeton Hydro brought fresh perspective to a complex and controversial problem that has plagued southeastern Massachusetts for decades.  In late March 2013, our team was notified that our application would receive funding – our contract required that we complete all of our activities by June 2013 and issue our final report by mid-July.

Princeton Hydro examined an abundance of information regarding the macro-scale characteristics associated with Brockton’s water supply system.  Our review and analyses emphasized hydrologic and nutrient pollutant modeling of the individual water bodies that make up Brockton’s primary water sources.  Our objective was to evaluate the water supply system in the context of the overall natural resource regulatory framework as well as the impacts that current water management practices exert on the ecosystem, including the numerous ecosystem services that humans rely upon.Water Budget Chart

Overall, our evaluation of Brockton’s water sources demonstrated that existing water management practices are not sustainable – we showed that in an average year, Brockton uses the equivalent of every water drop that enters the Silver Lake watershed as precipitation.

Furthermore, Princeton Hydro demonstrated that the artificial movement of water across natural watersheds results in a suite of negative consequences for ecological and human communities that inhabit the setting.  The primary negative impacts of water management practice include deviation from natural stream flow regime in three watersheds: Jones River (Jones River watershed), Stump Brook (Taunton River watershed), and Herring Brook (North River watershed); accelerated cultural eutrophication of Monponsett Pond and Silver Lake; and, heightened concern for the long-term integrity of sensitive environmental settings such as the Stump Brook Wildlife Sanctuary and the Burrage Pond Wildlife Management Area.

Clean Flowing Water Defines Healthy Streams

As reported by USGS in Circular 1391, reduced stream health most frequently relates directly to manmade modifications of the physical and chemical properties of streams.  Maintenance of stream health in the face of land development requires that the physical and chemical properties of streams remain within the bounds of natural variation.  Land and water management practices lie at the heart of reduced aquatic ecological integrity.  The most common factors for reduced stream health include:

  • Stream Flow Fluctuation
  • Nutrient Enrichment
  • Changes in Temperature Regime
  • Changes in Light Availability
  • Contaminants
  • Exotic Taxa

Despite some of the bleak statistics reported by USGS about stream health in the US, Circular 1391 provides insight that can guide land and water managers toward better overall stewardship and even remediation of ecologically-damaged waters.  Moreover, although a distinct majority of streams exhibit altered biology, even in urban settings, USGS showed that more than 10% of assessed streams were not biologically altered and that statistic points to a silver lining; meaning that unaltered aquatic communities can be compatible with urban settings.

Possible Management Options for Brockton

The Brockton water system amounts to an unsustainable use of sources for water consumed well beyond the source setting.  The strain on waters in the source areas leads to cascading impacts on water quality, ecosystem functions, and property value – impacts that are consistent with diminished ecological integrity reported by USGS in Circular 1391.

As USGS demonstrated, there is widespread evidence that stream flow and nutrient status are the most critical variables for stream health, and by extension – aquatic health in general.  USGS also suggested that management strategies aimed at restoring aquatic health are best developed and applied at the local/ watershed scale, where there is an understanding of how land- and water-management activities modify the physical, chemical, and biological attributes of streams.

Princeton Hydro recommended that the most obvious alternative to existing water management practice is to apportion the Brockton water supply to more and/or different sources in order to alleviate strain on Silver Lake, Monponsett Pond, Furnace Pond and their respective individual watersheds – Brockton’s consolidation of three headwaters watersheds in order to export water to a distant region contradicts the basic tenets of modern watershed science.

Since 2008, a desalination plant (Aquaria located in Dighton, MA) has offered a seemingly sensible alternative source for Brockton to eventually offset as much as 50% of the approximately 9 million gallons of water currently sourced from Silver Lake daily, yet the City (despite a 20-year contract that requires multi-million dollar payments to Aquaria annually) declines to accept Aquaria’s desalinated water as an offset to its Silver Lake source.

Among conceptual alternatives for supply, we also suggested directly feeding stock water from Monponsett Pond (and/or Furnace Pond) into the Silver Lake WTP in lieu of diverting and diluting millions of gallons of nutrient-enriched water per year into the comparatively clean waters of Silver Lake.

Princeton Hydro also suggested that horizontal alignment of extraction wells placed into the highly transmissive Plymouth – Carver – Kingston – Duxbury (PCKD) aquifer system would represent a less ecologically-damaging water source that also could provide feedstock to the Silver Lake WTP.

Princeton Hydro readily acknowledges that development/utilization of any water source alternatives to the current Silver Lake system will require new capital investment or other additional costs by Brockton, but the long-term cost of unsustainable water supply management by Brockton is a costly endeavor right now.  And in the case of Brockton’s water supply system, Brockton and its customers are not bearing all of the current costs of its water management practice.

Even in a water-rich region like southeastern Massachusetts, deep conflicts over water management practices can and sometimes do erupt.  The magnitude of long-term water withdrawal that exceeds sustainability depends on the hydrologic effects that society is willing to tolerate, including the actual cost of infrastructure, labor, energy, and related items necessary to obtain, treat, distribute, and otherwise manage land and water resources responsibly.

Decision-makers today and in the future face increasing strains on natural as well as economic resources and particularly for water resource stewardship, sustainable management is becoming less an idealized notion and more an imperative.

[1] Carlisle, D.M., Meador, M.R., Short, T.M., Tate, C.M., Gurtz, M.E., Bryant, W.L., Falcone, J.A., and Woodside, M.D., 2013, The quality of our Nation’s waters—Ecological health in the Nation’s streams, 1993–2005: U.S. Geological Survey Circular 1391, 120 p., http://pubs.usgs.gov/circ/1391/.

[2] USGS defined altered as the numbers and types of organisms were substantially different when compared to a regional reference stream.

Habitat Fragmentation – Culvert Blockages and Solutions


Culvert that is “perched” due to scour by high velocity flows through the pipe. ©Princeton Hydro.

The Bucks County Chapter of Trout Unlimited (Pennsylvania) and the Cooks Creek Watershed Association were featured in the Summer 2013 edition of Trout magazine, TU’s national publication, for their culvert inventory work in the Cooks Creek watershed.  Princeton Hydro was glad to assist via directly investigating and training of volunteers to inspect and document potential culverts in need of retrofit.  Princeton Hydro also completed design concepts and opinion of costs for two example culverts.  Identified culverts in need of retrofit will help the creek’s wild brown and brook trout.  Princeton Hydro based the training on the Vermont guidelines for rating culverts for pass-ability.  In this small watershed a total of 97 culverts were identified with 32 of them as potential barriers, and 11 identified as “high priority” in need of retrofit.

Why worry about culverts, you say?

One of the most unforeseen danger to the biodiversity in our river networks is habitat fragmentation through un-passable culverts throughout the United States.  While blockages via dams number upward of 100,000 or so, the blockages created by ecologically and biologically inefficient culverts is likely to number in the millions.   The majority of these culverts are located in headwater areas of rivers, which entail greater than 50% of most river miles in a watershed; a large cumulative impact.  As a result, native key headwater species such as brook trout (Salvelinus fontinalis) in the East and cutthroat trout (Oncorhynchus clarkii) in the West have had their historic ranges reduced to a fraction of their former extent.

Historically, culverts were designed by civil engineers to maximize flow capacity and minimize pipe size in order to create the most economical structure for developers, transportation authorities, and municipalities.  The unfortunate by-product of such a design approach is that water velocity through culverts is extremely high, often running in supercritical flow, even during base flow conditions, and the smooth and featureless surfaces in the structure make it extremely difficult to navigate.  To add insult to injury, the high velocity flows also scour and erode the stream channel immediately downstream of the culvert, leaving the pipe too high out of the new channel (“perched pipes”) for organisms to pass.  Downstream water dependent organisms cannot pass upstream to new habitat, and those populations upstream become extirpated due to downstream migration and mortality, and the lack of an ability to return or be replaced.  A study of impacts of fragmentation on brook trout is ongoing by the USGS Conte Anadromous Fish Research Center (USGS CAFRC) and others, and a study recently completed documented the impacts of fragmentation of local populations provides an informative view of the blockage potential of culverted streams.

There is hope in the re-connection of stream habitat through new research and initiatives developed since 1999.  One such approach is through the Stream Simulation design originally developed in its present form at the Washington State Department of Fish & Wildlife and adopted by the US Forest Service, US Fish and Wildlife Service, as well as others, and was also adopted shortly thereafter and refined by the University of Massachusetts, Amherst Extension (Stream Continuity model) for use in Northeastern States (initially in the Massachusetts River and Stream Crossing Standards, and then adopted in similar form by surrounding states).  Through the Stream Simulation/Continuity method, a culvert is not simply measured in terms of hydraulic efficiency, but also in terms of ecological and biological efficiency.

In the most basic terms, Stream Simulation (Continuity) requires a crossing that has a minimum width of the bankfull flow of the natural channel upstream and downstream, plus more width to allow passage of terrestrial organism passage such as reptiles and amphibians (in the UMASS model the increase in width is 20% wider than bankfull, but in the current Washington State model they use 20% plus 2 feet).  The other part of the design requirement is an opening area to length ratio to allow the maximum amount of natural light penetration into the culvert (openess ratio), as many organisms, such as fish, are too intimidated to travel through dark culverts.  Other design requirements include the use of slopes and velocities that allow for fish passage, and roughness (i.e. placement of natural substrate) to also slow down the flow.

The key challenge for the retrofitting of culverts to be more passable is cost.  As with any civil engineering project, the larger it is, the more expensive.  To replace a 36 inch diameter culvert with a 10-14 foot wide structure could increase the cost by 10-fold.  However, there are ways in completing an economic analysis to justify the costs.  For example, most culverts were historically only designed to pass storms up to the 25-year event, but in even more cases, never were sized by engineers.  A larger culvert will increase its capacity and reduce overtopping events that would require road closings and worse, cause the roadway to collapse.  Road closings require emergency management and road crews to set up detours and slowing down commerce, or worse require repetitive reconstruction efforts that, over time, may exceed the cost of installing a Stream Simulation designed culvert.


Same culvert as in photograph above, after the retrofit using Culvert Simulation. ©Princeton Hydro.

Other ways of encouraging installation of these larger and passable culverts is through the permitting process.  In New England, the US Army Corps of Engineers, allows for a by-pass of a formal review for their approval if the Stream Simulation guidelines are followed. This approach can save a significant amount of time to fast-track a retrofit.  To complement the Corps’ permit facilitation process, the states of Connecticut, Massachusetts, New Hampshire, and Vermont, have developed stream crossing guidelines to meet the Corps’ permit by rule compliance.  These states have even instituted state level regulations requiring aquatic organism passage via the Stream Simulation model.

Princeton Hydro was contracted to design a culvert retrofit to replace a 36 inch diameter culvert with a 12 foot wide arch culvert on a tributary of West Brook which is being monitored as part of the USGS CAFRC research project in Massachusetts.  This retrofit will be used to assess the increase in efficiency of headwater stream accessibility by local brook trout populations.

It would appear that the Stream Simulation or Continuity model is catching on, however, there needs to be more outreach and changes to existing rules in other regions of the US.  Further studies, such as that being conducted by USGS and their partners, will determine the true benefits of increasing culvert fish passage efficiency and bolster the economics of protecting fish populations for future generations.
Geoffrey M. Goll, P.E.
Vice President and Founding Partner

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Dam removals in New Jersey – how did we get here?

In the aftermath of Hurricane Floyd in 1999, it became painfully evident that the many dams in and around the state were woefully obsolete. Obsolescence occurs on a dam when it, either through climactic changes or antiquated designs, is unable to safely pass those infrequent yet highly destructive floods. Obsolescence can also occur when earthen embankments or concrete structures have deteriorated to the point of no longer providing safe resistance to seepage and impounding water behind the dam. The threat to the public living in the path of a potential flood wave that results when a dam suddenly bursts is varied but can have serious consequences and liabilities for dam owners.

Following the hurricane, the NJDEP Bureau of Dam Safety sent letters to all the dam owners in their records reminding them of their obligation to maintain their regulated structures in compliance with the Dam Safety Regulations. It was serendipitous that, at the same time, American Rivers and the National Oceanic and Atmospheric Administration (NOAA) started a program called the “Community-Based Restoration Program River Grants,” whereby grants were made available to remove obsolete dams to allow for migratory fish passage. The Natural Resource Conservation Service (NRCS) and the US Fish and Wildlife Service (USFWS) at the same time started looking to dam removals as meeting the restoration criteria for their funding programs.

These sources of funding were serendipitous as “dam safety compliance” not only means the renovation of a dam to meet current standards, but the elimination of the structure altogether is a means of compliance: no dam, no regulatory requirements. This grant opportunity opened up a whole new set of funding sources for dam owners that did not have the wherewithal or desire to maintain a highly regulated and risky structure.

The first dam to fall in the state for the benefits of dam safety compliance and migratory fish passage was the Harry Pursel Dam on the Lopatcong Creek in Phillipsburg in 2001. The next dams were the Gruendyke Mill Dam and Seber Dam on the Musconetcong River in Hackettstown under the leadership of the Musconetcong Watershed Association in the mid-2000s. Princeton Hydro was proud to be a part of each of those removals, and so many others – from North Carolina to Vermont.

Momentum for the removal of the thousands of obsolete dams across the country has increased; New Jersey has no dearth of them. There are plenty. However, as the recent economic recession has hit the private sector, so too has it impacted the availability of government funds to restore natural resources for the public good. Fortunately, other vehicles have been developed to fund dam removals.

In the past several years, Princeton Hydro completed the first dam removals used for the purpose of offsetting wetlands impacts, through projects in Hunterdon and Ocean County. Now, others are following in the path cleared by these projects to boldly use dam removal for the mitigation of wetlands impacts and other types of natural resource damages.  NJDEP is formally in favor of removing dams in the name of restoration, and is even encouraging the removal of obsolete dams as such projects achieve many positive public safety and environmental goals.

It will be vitally important to maintain creativity for funding opportunities and promote public awareness of the importance of dam removal as a cost effective restoration tool.  As a result, the removal of obsolete dams can continue well into the future. If you are interested in further understanding the regulations in NJ, benefits of removal, and examples illustrating dam removals, please visit the following sites:

American Rivers – Dam Removals in NJ
Other dam removal resources from American Rivers
Clearing House for Dam Removal Information

Geoffrey M. Goll, P.E.
Vice President and Founding Partner

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