Executive Committee 2023-24


Landscape Architect, Smithsonian’s National Zoo and Conservation Biology Institute

Matthew Sellers is a 21-year resident of the DC area, moving here from Ohio for graduate school at Virginia Tech in Alexandria, VA. His education is in urban planning and landscape architecture. He is a landscape architect licensed in the state of Maryland, and member of ASLA. His professional history includes work with the landscape architecture firms Stephenson + Good (9 years) and Clinton & Associates (5 years). He also taught courses in the Landscape Design and Sustainable Landscapes program at George Washington University (12 years). Matthew’s experience includes the design and construction administration of residential gardens, public plazas, playgrounds, perimeter security master plans, multi-acre mixed-use neighborhood developments, and animal habitats. Currently he is the Landscape Architect at Smithsonian’s National Zoo and Conservation Biology Institute providing thoughtful and creative planning and design solutions for the Zoo’s visitors and inhabitants.


Landscape Architect, Rhodeside & Harwell

Jules Krinsky is a creative problem solver, landscape architect and urban designer who has worked in the Washington Metropolitan area since 2012.  Currently, Jules works as a Landscape Architect with the multi-disciplinary firm Rhodeside & Harwell in Alexandria, VA.  At Rhodeside & Harwell, Jules works on projects ranging from small local parks to US Embassy projects around the world and everything in between.

Jules received a bachelor’s degree in Landscape Architecture at the University of Georgia and a Master’s of Science in urban design at Georgia Tech.  He is a licensed Landscape Architect in the State of Maryland.

Immediate Past President

Landscape Architect, Lila Fendrick Landscape Architects

Carla Ellern, RLA, ASLA, LEED® AP BD+C is a registered landscape architect with Lila Fendrick Landscape Architects in Chevy Chase, MD. She received her Master’s in Landscape Architecture from the Graduate School of Design at Harvard and would like to spread the word about what landscape architects do through her involvement with Potomac ASLA. In the public sector, she worked for the Department of Environmental Protection (DEP), Montgomery County, Maryland in the RainScapes program where she worked with homeowners and communities to reduce stormwater runoff. She’s interested in improving the environment and people’s lives by expanding green infrastructure and sustainability in our landscapes.


Landscape Architect/PB

Rob Tilson, FASLA, PLA has held many positions for the Potomac Chapter. Most notably, he has served as a two-time President from 1993-1994, two-term Trustee from 1998-2003. While serving in these capacities, Rob represented the chapter on the Virginia Licensure Committee (1998-2001), 100 Parks/100 Years Program Committee (1998), and the Centennial Medallion Program Committee (1998). Rob also instituted and re-organized the Nominating Committee for the Chapter and served as Chairman from 2002 to 2003. He co-chaired the Host Committee for the 2010 ASLA National Meeting in Washington, DC.

Nationally, Rob has served in several capacities including ASLA Vice-President of Professional Practice from 2004-2005. During his tenure as Vice President, Rob helped launch the SITES initiative and revamped the Professional Practice Network program and led the Archive Committee to help establish the Fellows database. Rob also served as the Board of Trustees Representative on the Landscape Architecture Foundation Board (2003). In 2005, Rob was recognized as a Fellow for his service to the profession.

As Chapter Trustee, Rob will concentrate on increasing Chapter visibility with other allied professions and work to promote Landscape Architecture and continue to serve as a leader within the ASLA Board of Trustees.

Rob received his Landscape Architecture degree from Purdue University and has been practicing landscape architecture in the Washington, DC metro area for over 30 years. Rob is licensed in Virginia and Maryland.


Landscape Architect, STUDIO39 Landscape Architecture

Loren Helgason is a registered landscape architect at STUDIO39 Landscape Architecture in Alexandria, Virginia. With over 20 years of experience in the Mid-Atlantic and beyond, he has been involved in a broad range of projects including residential, hospitality, office, retail, and government.

Prior to putting roots down locally, Loren received a Master of Landscape Architecture from Kansas State University and a Bachelor of Science in Architecture Studies from the University of Nebraska-Lincoln. With this background, he looks at the interface between design, engineering, and natural systems to uncover engaging solutions that celebrate this overlap.



Dan is an accomplished Urban Planner and Professional (licensed) Landscape Architect with LEED accreditation and over thirty-five years of project experience in master planning, streetscape design and green infrastructure, urban design, and landscape architecture in both the public and private sectors. He concentrates on bridging the gap between large-scale planning/visioning efforts, or concept design, and the more detail-scale design solutions that can be implemented, are cost effective, and that meet sustainability criteria. He currently works with the National Park Service on special projects, including cultural landscape projects, and is also working on several other projects in the District of Columbia and Texas.  He has a special interest in urban waterfronts, urban streetscape design, green infrastructure, and historic preservation.

Dan currently serves on the Executive Committee as the Treasurer for the Potomac Chapter, and previously served as the Secretary for the Maryland Chapter. He is a member of the committee to Save River Farm which has received awards from the Virginia Garden Club and the Potomac Chapter of ASLA and is a contributing member of the Urban Design-Professional Practice Network.  He previously served as the professional representative to the Urban Design Advisory Committee in Alexandria (ten years), as a member of AIA/Cleveland-Regional  Urban Design Assistance Team, as a volunteer at the Alexandria Seaport Foundation, and as a volunteer at the American Horticulture Society. His previous urban design work with a colleague in Houston for the renovation and rehabilitation of the 9th Street Mall in Miami was awarded first place in a competition sponsored by the Miami Chapter of the AIA.


Landscape Architect, AECOM

I discovered landscape architecture when I was in graduate school and was fascinated by its ability to directly address the ecological concerns of the built environment.  I worked for my landscape architecture professor (Diana Balmori of Balmori Associates) while in architecture school. After graduating, I looked for opportunities where architects could work closely with landscape architects to develop integrated solutions for buildings and sites.  After obtaining my architecture license, I transitioned to the landscape architecture profession, becoming a licensed landscape architect in 2021.

I am a landscape architect, project manager, architect, and urban designer currently working at AECOM in the Buildings + Places group. My interests include landscapes over structures, the integration of landscape and architecture elements, and resilient landscapes in the urban environment. In the past several years, I have led landscape architecture and architecture design projects that range from re-envisioning urban streetscapes to creating design guidelines for federal campuses. I have worked within a variety of market sectors including commercial, health care, arts & cultural, government, and higher education projects. I am very much looking forward to serving as a Member-at-Large for the Potomac Chapter of the ASLA.

Landscape Architect, STUDIO39 Landscape Architecture

Amanda is a landscape designer whose experience has involved a wide array of projects over the years, ranging from multi-family to urban and zoological design. She started her career working for a local civil engineering firm in Pennsylvania after graduating from Penn State University in 2014. She eventually went on to join a zoological design firm, working for zoos across the country. From 2018 to 2020 Amanda served on the board for the Pennsylvania-Delaware Chapter of ASLA, and as Eastern Section Chair, she worked to advocate for licensure and help serve the local chapter. In 2021 she moved to Northern Virginia and is now working in the local Virginia and DC areas. Recently passing the LARE (she is very excited about that!), Amanda knows the importance of ASLA, and its local chapters, as a tool for community and to serve emerging and established Landscape Architects. Outside of work she enjoys everything from gardening, singing, painting, and keeping her hobbies as diverse as her interests in design.

Principal, Conroy Landscape Architecture

Lesley Conroy is a licensed landscape architect, certified arborist ,and LEED accredited professional. After nine years of working in the DC area on domestic and international projects, she founded Conroy Landscape Architecture in 2021to work on community driven projects closer to home. Lesley has designed and managed projects that span a diverse range of scales, including government agency campuses overseas, commercial roof terraces and green roofs, public parks, university master plans, urban open space planning, and residential gardens. She has practiced in the DC area for the entirety of her career and is leading the Potomac Chapter’s effort to eliminate the sales tax on landscape architectural services in the District of Columbia. Lesley majored in environmental studies at the State University of New York College of Environmental Science and Forestry and went on to earn a Master of Landscape Architecture degree from Virginia Tech’s Washington Alexandria Architecture Center. She strives to find collaborative approaches to design problems and excels at working in complex urban environments. Lesley is licensed in DC, MD, VA, and WV.

Landscape Architect

Connie is president of LSG Landscape Architecture, based in Tysons, Virginia, and leads sustainable design efforts for the company. Connie’s work ranges from commercial, institutional, and planning projects to public streetscape revitalization, and her most recent work has concentrated on sustainable site initiatives and smart growth. Connie was recently involved with a ULI Advisory Services Panel for intensive community outreach supporting reclamation of public spaces in the context of an urban highway repositioning project. This collaboration has led to Connie’s increasing work with the social impact of Landscape Architecture. She holds a certification in Healthcare Garden Design. She also actively pursues and researches green and sustainable initiatives.

Connie graduated from the College of Environmental Science and Forestry in Syracuse, NY with a Master’s in Landscape Architecture. Connie’s involvement with organizations in the region includes service on the Planning, Zoning, and related committees in Fairfax County. She has served the Tysons area with contributions to the Park System Master Plan Advisory Group and participation in the Tysons Partnership Urban Design Council and the Sustainability Council. Connie regularly participates in ULI’s Placemaking Council, as well as serving on ULI TAP (Technical Assistance Panel) programs. Among her regional affiliations, Ms. Fan has been influential in the growth of the Greater Washington Asian American Architects and Engineers Professionals organization.

Senior Landscape Architect, Michael Vergason Landscape Architect, Ltd

Lan has over twenty years of experience working as designer and project manager for a wide range of projects, in scope and scale and in both the private and public realm. She received her Master’s in Landscape Architecture from the University of Virginia and is a licensed Landscape Architect in Virginia. Her works at Michael Vergason Landscape Architects have received both local and national awards. Beyond design and project management, Lan continues to advocate for gender equity in the design of the built environment. She presented on this topic at the Association for Community Design conference, American Institute of Architects Design DC conference, and Women in Architecture lecture series. To promote awareness of design in the urban environment in her local community, she partnered with local organizations to lead Jane’s Walks through DC and Arlington neighborhoods.

Senior Landscape Product Specialist | Vectorworks, Inc.

Tony Kostreski, PLA, ASLA is a landscape technology enthusiast bringing municipal, institutional, mixed-use, and high-end residential site design proficiency to his role as senior landscape product specialist at Vectorworks, Inc. Kostreski has improved the efficiency of design-build and landscape architecture firms across the United States through best practice workflows in design, modeling, documentation, GIS, and BIM.

Committed to empowering the next generation, Kostreski delivers customized workshops at universities, equipping students with essential tools. With a Bachelor of Landscape Architecture from the University of Maryland, College Park, Kostreski brings a solid educational foundation.

An active member of professional associations, Kostreski has served as the secretary and program committee chair for the ASLA Maryland Chapter and is currently a member-at-large for the ASLA Potomac Chapter and serves on the ASLA Digital Technology PPN. His expertise and dedication position him to shape the future of our local landscape architecture community, driving innovation and sustainability.

Principal, Jennifer Horn Landscape Architecture

Kara is a licensed Landscape Architect with over 10 years of experience. As Principal at Jennifer Horn Landscape Architecture (JHLA), she oversees the commercial and public work inthe office as well as key residential projects. Prior to joining JHLA, she worked as a Senior Associate at Oehme van Sweden (OvS), where she designed and managed a diverse mix of residential, commercial, and institutional projects, including the recently completed Circle of Remembrance at the National WWII Memorial. Prior to her time at OvS, she worked at Landscape Architecture Bureau, where she focused on multi-family mixed-use projects, city parks, and playgrounds within the greater DC region.

Campus Landscape Architect, National Institutes of Health

Connor Price is a licensed landscape architect in Maryland and Washington DC. Connor has a wide range of professional experience in landscape architectural design, project management, planting design, and construction administration in both the public and private sectors. Currently, Connor serves as the campus landscape architect for NIH in Bethesda, MD. At NIH, Connor reviews all new site design projects on campus, oversees site construction, creates landscape policies for all of NIH’s campuses across the country, and serves on design review committees.

His previous experience working on college campuses for a multidisciplinary design firm has provided him with the tools to engage with large stakeholder groups, as well as tackle projects at multiple scales. Mr. Price holds a BLA in Landscape Architecture from West Virginia University. Connor lives in Baltimore, MD. and enjoys volunteering his time for The Neighborhood Design Center, which helps local Baltimore neighborhoods by providing design services and securing funding for parks and other community spaces.

Division Manager, CPJ

Amy is relatively new to the DMV area, having moved to Maryland two years ago from the New York City area to join Charles P. Johnson & Associates and is the Division Manager for the Silver Spring Planning Department. She is excited to get more involved locally after having been active in the NYASLA chapter for many years. At CPJ, Amy enjoys collaborating on projects with multiple disciplines and mentoring junior staff. She has over 20 years of experience in the industry, having worked on a wide range of complex projects from housing developments to green roofs, waterfronts, campus masterplans, transit stations, historic sites, schoolyards, and public parks throughout the East Coast. Amy currently holds licenses in Maryland and New York and is a LEED AP. Before moving, she served on the Hoboken (NJ) Shade Tree Commission for 6 years and was Chair for 3 years. As Chair, she lead the annual street tree planting program, approved tree planting and removals for new development, advised the Special Improvement District, and planned Arbor Day events with local schools.

Amy grew up on Long Island, NY and holds an undergraduate degree from Cornell University and an MLA from the Rhode Island School of Design. Outside of work, she is a huge history buff and has been enjoying working on her house in Kensington and exploring the DMV area with her husband and two daughters.

Project Manager, Landscape Architect, and Arborist | Kimley-Horn
Davis Walker serves as a Project Manager, Landscape Architect, and Arborist at Kimley-Horn, focused on landscape architecture/ land development projects. His work predominantly consists of commercial retail, multifamily residential, Parks and Recreation and Public Streetscapes. Davis has a passion for the built environment and all that it impacts. Davis graduated with a Bachelors of Landscape Architecture from the University of Georgia. Outside of work, he enjoys fly fishing, boating & golden retrievers. 

Executive Director

Christine Cotter

Before joining the Potomac Chapter of ASLA as Executive Director, Ms. Cotter was Vice President, Public Relations at American Professional Agency, Inc.  She brings more than 20 years experience in managing and working with membership organizations, as well, including the American Society of Psychoanalytic Physicians, American Psychiatric Association district branches, Maryland and District of Columbia Society of Clinical Oncology, and others.  Cris works with our boards and volunteers and is responsible for the administration of the association, as well as membership retention and services.