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Posted on May 9, 2019

Waterborne’s published research is now available online.



Waterborne, Nutrients and Soil Health

Posted on May 9, 2019

Waterborne is leading the development of integrated investigations advancing grower and commodity groups’ knowledge of crop inputs and their movement through the environment following application. Now, these groups and their grower members can more effectively adapt their nutrient management practices for improved soil health, increased yield and better environmental outcomes.

Our services in nutrient management and soil health include, but are not limited to:

Access to diverse expertise/Specialized methods in sampling and application/Web-based data & modeling/Quality technical writing/Geospatial solutions/Regulatory support services/Crop protection research & solutions/Stewardship & sustainability metrics

For more conversations with our experts in nutrients and soil health, please contact Greg Goodwin


Going Mobile

Posted on January 25, 2018

Halfway around the world from me scientists use smartphones to take photos and collect specific information on crops, management practices and land use. I, on the other hand, am comfortable in my office watching their progress on a web-based map, drinking a warm cup of coffee and writing this article.

With the arrival of the smartphone, technology became increasingly more accessible and commonplace in our everyday lives. The sheer fact we can collect information remotely using smartphones is an amazing advancement in technology. The number of mobile applications has skyrocketed and now reaches upwards of 100,000 within a few years of the release of the first-generation Apple® iPhone in 2007. Waterborne utilizes mobile applications and now creates them with very little effort and custom programming on our end.

Several years ago, ESRI released a new mobile platform, Survey123. This application allows users to setup a survey, associated maps, and use mobile platforms (e.g., iOS®, Android®, Windows®) to collect information in the field. There are several advantages to this technology. Surveys can be created using a spreadsheet for data collection. The application also contains standardized menus, support for various media (e.g., photos or drone videos), and support for multiple languages. All information can then be streamed to a central location. Others can then view the information, live, on a web-map or dashboard and follow the progress in the field.

The use of smartphones and other commonly used mobile devices has the advantage of a small learning curve for software and usability. Furthermore, since smartphones are used ubiquitously, you can tap into the local users base to collect the information you need. This provides significant cost savings on any project and reduces the amount of time spent collecting information.

Gerco Hoogeweg, PhD.
Chief Operations Officer, Geospatial Scientist



How Much Degradation Occurs in Sewer Systems?

Posted on January 25, 2018

Exposure modeling plays an important role in national-scale risk assessment of chemicals that are disposed of down-the-drain (for example, home and personal care product ingredients). Exposure models commonly account for chemical removal that occurs during wastewater treatment processes at treatment facilities. However, for many chemicals, a significant amount of removal (biodegradation) can also occur in the sewer system. Combining chemical-specific biodegradation data from laboratory studies with estimates of typical “sewer residence times” provides a way for exposure modeling to represent this aspect of environmental fate and transport. However, given the thousands of municipal sewer systems across the U.S., how can we estimate the typical range for sewer residence time?

Waterborne scientists collaborated with scientists from Procter & Gamble to address this question in a recent study by developing a geographic information systems (GIS) approach to estimate the distribution of sewer residence times for the U.S. using road networks as a spatial proxy for sewer networks. While available data for sewer networks is limited, we evaluated the similar spatial distributions of case study sewer networks and road networks. Building upon that analysis, our experts analyzed the spatial distribution of population density and over 3,400 facility locations across the U.S. to estimate sewer residence times using existing national datasets and sewer system design standards.

Our analysis estimated a median sewer residence time of 3.3 hours for the U.S, which is comparable to values reported in literature. The distribution of residence time values generated from our analysis enables this parameter to be represented probabilistically (instead of just as a single point value) which adds robustness to risk assessments. Using our analysis results, we estimated in-sewer removal across a range of hypothetical, but realistic, chemical biodegradation rates to illustrate that a significant amount of removal is likely to occur in the sewer for many chemicals. We also specifically evaluated a group of readily biodegradable surfactants used in home and personal care products for which biodegradation data was available, and estimated removals of 62% to 99% during sewer transit (based on a median residence time of 3.3 hours). Significant in-sewer removal estimated for many down-the-drain chemicals has implications for estimation of influent concentrations at wastewater treatment facilities, and ultimately for predicted environmental concentrations in receiving waters.

This study is an example of how best-available data resources can be paired with advanced GIS capabilities to address important data gaps in exposure modeling and add value to the environmental risk assessment process. The work was recently published in Science of the Total Environment.

Kapo, KE, Paschka, M, Vamshi, R, Sebasky, M, McDonough, K. 2017. Estimation of U.S. sewer residence time distributions for national-scale risk assessment of down-the-drain chemicals. Science of the Total Environment 603-604:445-452. https://doi.org/10.1016/j.scitotenv.2017.06.075

Contact Raghu Vamshi at vamshir@waterborne-env.com with questions about our down-the-drain expertise.


The Growing Popularity of Subsurface Tile Drains

Posted on January 25, 2018

Agricultural subsurface tile drainage is a practice that has been around for many decades but has recently become increasingly popular among growers throughout the Midwest, given improvements in technology and increases in commodity prices. This practice allows growers to effectively change the drainage properties of their land to remove excess water and recover some of the most fertile soils that could otherwise not be farmed. Subsurface tile drainage has become so prominent in some agricultural regions that drainage districts have been formed, leading to excavated man-made drainage ditches providing landowners a place for the water to go in order to make land arable.

Paired field, subsurface tile and rainfall monitoring stations

While this practice has been extremely effective in achieving its primary goal, it has not come without a cost. Just as it allows water to circumvent natural drainage pathways and associated soil retention times, it also allows any constituents in that water to do the same thing. This has led to an undeniable effect on the water systems that receive agricultural drainage tile discharge. However, given its vast benefits to growers who are constantly challenged with feeding an ever-growing population, the associated externalities of this practice must be weighed and carefully considered.

Agricultural subsurface tile drainage, automated water monitoring station installation

As a result, Waterborne Environmental has partnered with commodity groups in three states in the Midwest to complete six different monitoring and numerical simulation projects. These projects examined the issues related to agricultural tile drainage, putting them into perspective across the broader landscape, and evaluated the effectiveness of conservation best management practices to meet constituent loss reduction goals. As a company with locations throughout the corn belt and a team with families rooted in agriculture, we are very sensitive to the delicate balance that must be struck between protecting grower interest and shielding the environment and that optimal balance is exactly what we aim to achieve through projects such as this.


Population Modeling: A Valued Instrument for Ecological Risk Assessments

Posted on January 25, 2018

In recent years, across industries, there has been a significant amount of effort invested in the application of population modeling for ecological risk assessments (ERAs). Waterborne’s increasing expertise in applied population modeling has contributed to the strategy and direction of ERAs through the development of case studies and the introduction of a systematic approach for the development of population models. Population models and other ecological modeling approaches can combine data and knowledge about species, its habitat, and exposure-effects relationships. Temporal and spatial aspects of a species’ habitat use and potential exposures can be considered explicitly.

A critical challenge to address is how to effectively implement population modeling within the ERA framework. Waterborne ecological modeler, Dr. Amelie Schmolke, and her co-authors have introduced a systematic approach for effective implementation of population modeling for pesticide risk assessments (Schmolke et al. 2017a). The proposed decision guide increases the efficiency and transparency of population model development, making population models more readily applicable in pesticide risk assessments. The decision guide is organized in four phases illustrated in Figure 1 for an example of herbaceous plants.

Graphic overview of the decision guide for minimal conceptual model development, starting with the phase defining model objectives and systematically moving to subsequent phases. Reproduced from Schmolke et al. 2017a

In Phase I, the model objectives are compiled systematically. The purpose of the model is defined in detail and aspects of the model may be determined prior to its development.

During Phase II, available data regarding the species of interest are compiled, as well as the pesticide exposure and the toxic effects relevant to the species. The resulting tables contain the information relevant for the model development along with the uncertainties in the data. Data gaps are identified systematically, and inform the details and assumptions in the conceptual model.

Phase III (decision steps) is comprised of the step-wise decisions needed to develop a minimal conceptual model. In this case, ‘minimal’ does not imply simplicity, but rather the “lowest level of complexity necessary to meet a given study objective” (Schmolke et al. 2017a). First, a life-history graph is prepared for the species of interest based on available data from Phase II. A series of seven decision steps are then followed by the model developer, addressing organism-level processes, temporal representation, spatial representation, density dependence, population status and environmental conditions, and indirect effects. The decision steps represent an iterative process with refinements to previous phases and the life-history graph throughout the minimal conceptual model development.

In Phase IV (Summary of the Minimal Conceptual Model), summaries of each decision step are compiled into the minimal conceptual model. Uncertainties in the data used for the model development and model assumptions applied are characterized during this phase. The summary also specifies which output metrics will be collected with the implemented model. The minimal conceptual model can be used to assess and adapt existing models for the current purpose, or it can be applied as a blueprint for implementation of a new model. Additionally, the minimal conceptual model may identify and prioritize gaps in the available data which may need to be filled before the implementation and application of the conceptual model.

Waterborne developed a conceptual population model of the Mead’s milkweed (Asclepias meadii), an herbaceous plant listed as threatened under the Endangered Species Act (ESA), as a case example for the decision guide (Schmolke et al. 2017a). The implementation of the conceptual model made use of a published population model of the species and adapted and extended it for use in pesticide risk assessment. Dr. Amelie Schmolke and her colleagues analyzed a range of scenarios representing exposure-effects relationships for two herbicides and their effects on the populations simulated with the model. Using the Mead’s milkweed population model, they were able to estimate population-level effects of herbicides over extended time periods, which exemplifies an ecologically relevant endpoint for ERAs.

With a population model for another threatened herbaceous plant species, Boltonia decurrens (Schmolke et al. 2017b), Waterborne estimated the potential population-level impacts of different herbicides on this short-lived species. In this case, conservative in-habitat exposure scenarios were combined with dose-response relationships for growth and survival of standard test species, based on standard vegetative vigor and seedling emergence tests, and applied to the species-specific model. Exposures were distributed across the simulated habitat applying the RegDISP model for spray drift, and a combination of the Pesticide Root Zone Model (PRZM) and the Vegetative Filter Strip Model (VFSMOD) for runoff. This distributed exposure modeling approach made it possible to assess potential effects of herbicides on plant populations growing in habitats that border chemical use areas and was applied to assess the effectiveness of spray buffer zones as mitigation measures.

Population models can include indirect effects by linking food reduction to individual growth and fecundity

In another population model approach, Waterborne addressed potential indirect effects of pesticides on fish populations. The listed slackwater darter (Etheostoma boschungi) was used as an example species. The darter species’ diet is comprised of aquatic insects and small crustaceans. Some pesticides could potentially affect the food availability of the species for limited time periods even if fish are not affected by the compound. With the model, such indirect effects to the simulated populations can be evaluated over extended time periods as well as assessment of different assumptions. Through a combination of species-specific life histories and direct and indirect effects, population models can play a significant role in determining the potential risks of a chemical to populations of listed and other non-target species.

Amelie Schmolke

Amelie Schmolke, Ph.D.

Waterborne’s expanding depth and expertise in population modeling is continuing to provide a higher-level approach in ecological risk assessment. Contact Amelie Schmolke at schmolkea@waterborne-env.com should you have questions or be interested in learning more about population modeling and how Waterborne is using it to support ecological risk assessment.



Posted on July 13, 2017

In this issue of The Current, we would like to celebrate Waterborne’s Co-Founder, Patrick (Pat) Holden, who retired May 1, 2017, the start of our 25th year.

Pat moved to a small farm in Loudoun County, Virginia, from Alexandria, Virginia, at the age of seven. Moving to a rural, predominantly agricultural county in the early 1960s had a profound impact on him. Then, at the prodding of his high school chemistry teacher, he read Rachel Carson’s Silent Spring, which also left a lasting impression on him. These two pivotal events in Pat’s life sparked a passion for mitigation of environmental impacts from modern agriculture.
Immediately after undergraduate school at the University of California, Santa Cruz, Pat spent a year studying agroecology at the University of California’s Center for Agroecology and Sustainable Food Systems. He attended graduate school at the University of Arizona, studying hydrology with a focus on agriculture’s impact on water quality.

While in graduate school, Pat worked with renowned hydrologist and mentor, Gray Wilson, to prepare a primer on water well sampling for volatile organic chemicals to be used by public health agencies in the U.S. Pat also prepared a contract report for the Board on Agriculture of the National Research Council on the status of pesticide occurrence in ground water in four states in the U.S. His responsibilities included identifying, contacting and conducting field interviews with relevant researchers working for state agencies or universities in California, Wisconsin, New York and Florida, as well as federal agencies and numerous agricultural chemical companies. This report was published by the National Academy Press in March 1986.

After graduate school, Pat worked with the Water Science and Technology Board to manage the National Research Council’s (NRC) Committee on Irrigation-Induced Water Quality Problems and related subcommittees to advise the state of California and the U.S. Department of the Interior on environmental problems associated with irrigated agriculture in California’s Central Valley. His responsibilities included providing technical and administrative support to the committee and its subcommittees, preparing written materials and coordinating report production, conducting research on behalf of the committee, serving as a liaison with state and federal agencies and the U.S. Congress for budget management. He also participated in project development activities in the areas of contaminant transport models and western water markets.

Pat’s NRC report on pesticides in groundwater caught the attention of the U.S. Environmental Protection Agency’s Office of Pesticides Programs (OPP) and he was subsequently hired to manage their groundwater section. The NRC report continues to be requested from the National Academy of Sciences, Engineering and Medicine (and on Amazon) and cited to this day.

While working for OPP, Pat served as one of the technical advisors to the Agency’s Ground-Water Task Force, headed by USEPA’s Deputy Administrator. Pat also served on various committees sponsored by the National Agricultural Chemicals Association (former name of CropLife America), U.S. Geological Survey (USGS), U.S. Department of Agriculture (USDA) and environmental groups addressing agriculture and water quality issues.

In 1987, Pat and Marty Williams, Co-Founder of Waterborne, met while both working for the USEPA. Pat and Marty founded Waterborne Environmental, Inc.in 1993, and quickly established relationships with clients that have continued to this day. Initial work led by Pat included several multi-state groundwater monitoring studies for pesticides in rural wells. His responsibilities included providing training to state personnel regarding rural well selection and proper sampling methodology under USEPA Good Laboratory Practice (GLP) Standards.
He also served as the principal investigator for ten small-scale prospective ground-water monitoring studies and one small-scale retrospective ground-water study in Florida, Indiana, Minnesota and North Dakota. He has helped author numerous protocols, site characterization reports, and progress reports related to these studies.

As Waterborne grew, Pat dedicated much of his time to running the business. He served as President from 1993 through 2007, and Chief Executive Officer until his retirement. He will continue to serve on the Board of Directors of the Company.
On Monday, May 1, Waterborne employees gathered in the Leesburg office to celebrate Pat and his retirement. Waterborne has had a profound impact in the area of environmental science and product registration around the globe. Marty said at Pat’s retirement gathering, “On behalf of everyone at Waterborne, I’d like to celebrate Pat Holden’s dedication to science, environmental stewardship and for helping to launch the careers of many scientists and engineers. Thank you, Pat!”.
While letting go is difficult, Pat is also looking forward to more free time. In retirement, Pat intends to pursue passions related to hiking, fly fishing, bee keeping and sustainable agriculture.


Waterborne’s Continued Focus on Pollinator Protection

Posted on December 19, 2016

Pollinator on Flower

Pollen collection

In the Spring 2015 edition of The Current, we updated our readers on our expanding expertise in pollinator protection. Since then, we have grown our pollinator risk assessment expertise and increased our involvement in this important area. Regulatory agencies and industry stakeholders maintain focus on this issue and Waterborne has enhanced its role in the efforts to address this complex ecological challenge.

As with many other ecological challenges, Waterborne is proud to stay on the pulse of regulatory and industry activity in the area of pollinator protection. Our ecotoxicology team has been busy with the strategy and management of acute and chronic laboratory testing for both larval and adult honey bee life stages. Our field studies team continues to conduct or manage pesticide residue studies for pollen and nectar on various crop types. In June 2014, the Office of Pesticide Programs (OPP) of the USEPA, along with the Canada Pest Management Regulatory Agency (PMRA) and California Department of Pesticide Regulation (CDPR) released a Guidance for Assessing Pesticide Risks to Bees. Waterborne’s risk assessment experts are well-informed on this guidance and are currently conducting hazard and risk assessments involving pollinator species. We are also applying honey bee colony modeling that can be used in higher-tier risk assessment. Within the context of endangered species risk assessments, Waterborne is investigating potential impacts on pollinators including bees and other pollinator species.

Waterborne will continue to develop expertise in order to address the multifaceted problem of pollinator protection. For more details on Waterborne’s expertise in pollinator protection, please visit https://www.waterborne-env.com/expertise/pollinator-protection/.

Contact Jenn Collins, Lead Ecotoxicologist, with questions at collinsj@waterborne-env.com.


8th European Modelling Workshop

Posted on December 19, 2016


In early October, Amy Ritter attended the EU Modeling Workshop held in Athens, Greece, along with 51 other attendees comprised of industry, regulatory agencies (EU and Member State), academia and consultants. Waterborne experts, Gerco Hoogeweg and Isha Khanijo, were acknowledged in the presentation, “The difficulty of understanding leaching drivers from EU wide modelling assessments”, given by Paul Sweeney (Syngenta). A presentation on registration in China mentioned Waterborne for developing the PRAESS model and scenarios for predicting exposure in surface water, ground water and soil from pesticide use on cotton, corn and rice. For more information, contact Amy Ritter at rittera@waterborne-env.com.


Pesticides in Flooded Application Model – PFAM 2.0

Posted on December 19, 2016

Pesticides in Flooded Applications Model (PFAM) is an aquatic model used to estimate surface water exposure from the use of pesticides in flooded fields, such as rice paddies and cranberry bogs. PFAM was recently updated and scenarios in AR, CA, LA, MO, MS and TX were developed based on regional rice growing practices. Highlights of the improved model include the following:

Waterborne is familiar with the model upgrade. Contact Amy Ritter regarding our PFAM 2.0 capabilities at rittera@waterborne-env.com.

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