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Our Board Of Directors

The Ones Who Started It All

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Gretta Reischauer

Owner, Naturalist, & Executive Director

Gretta Reischauer has been a naturalist for over 30 years.


Starting at the Iowa 4H Education Center and Pilgrim Heights Camp, she then became the Director of Kiwanis Riverview Nature Center in Des Moines, IA.  


At TLC, she has developed several environmental education programs for our summer camps, adult continuing education classes, elder hostels, Field Schools, and in the classroom; plans and leads trips around the country for Jr. High and High School students; and has established an After-school program for middle school students. 

Gretta delivers most of our programs.

Gretta & Mark

Mark Reischauer

Director of Maintenance 

Mark Reischauer is the proud husband of Gretta Reischauer and father of Cameron, Hannah, and Jacobus Reischauer.


Mark is a master carpenter of 30 years and worked much of that time with Rich Lepper Construction.  In charge of bidding/purchasing and supervising construction sites, he has had to deal with customer relations and crew management.


He was raised on a farm and is very good at running and fixing heavy machinery, general maintenance, landscaping and hard labor.


Mark enjoys creating new construction projects for Threshold where he is given free range to plan, create, and build in any way he would like. Many of our unique and individual structures on the property came from these projects like the recycled silo home, the challenge course obstacles for team building, and the beautiful stage for our annual concert and for the use of weddings and other events. 


Anything we dream up, Mark can miraculously build and make it a reality. He is the reason that Threshold has the comforts and facilities that we do to offer to the public for events and even just for some people who need a place to stay. 

The Reischauer Children

The children of Gretta and Mark Reischauer have been taught an environmental ethic since birth.


They have done everything over the years, from setting tables to mowing and yard care, and helping on hikes or at our festivals for the public.


They have a great love for the outdoors and are always willing to share their experiences with others. All are very personable and can easily befriend the campers, especially those who seem apprehensive or out of the main group.


Hannah and Jacobus are proud members of our board of directors and Hannah has even recently been voted in as the President of the Board of Directors. Jacobus has recently joined the board after graduating from high school and helps where he can while attending college to pursue a Conservation Tech degree. Hannah and Jacobus's partners are also involved in helping where they can. Hannah's partner Alexander helps on the weekends during work days where he can when he is not working. Jacobus's partner Savanna has recently joined the board of directors and has now been voted in as the Vice President of the Board of Directors. Cameron, although not a member of the board, has, alongside his partner Caitlyn, continued to aid Threshold by helping set things up when they can and performing the past few years in the annual outdoor Fresh Air Concert.

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Hannah Marie Reischauer

President of the Board of Directors, Website Manager & TESL MA Student At ISU

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Jacobus Ellsbury-Reischauer

Board Member, Site Supervisor, & Conservationist

Jacobus has been involved with Threshold Learning Center his entire life. He was born the year that the land for Threshold was acquired and has enjoyed spending time and working to maintain the nature center from a very young age. 

Jacobus graduated from Colo-NESCO High School in May of 2021 and was voted onto the Board of Directors in March of 2021. After graduating from high school, Bus decided he wanted to continue his education in conservation.

Jacobus is now attending Ellsworth Community College in pursuit of his Conservation Technician degree. This degree has been very enjoyable so far for him and he is excited to continue learning more about the natural world within Iowa to contribute to the care and biodiversification of our property and restoration Prairie remnant.

"Bus" and his classmates and friends have played in the creek, meadows, and forest since they were 3 years old. They built a treehouse during the middle school after-school program. Today, as graduated individuals, Jacobus and his friends return to Threshold for epic airsoft and LARP battles as well as band practices before they perform in our outdoor Fresh Air Concert.


When it comes to what Bus does for Threshold, he helps whenever and wherever he is needed by mowing, weeding, aiding in minor and major maintenance and construction projects, caring for our seasonal garden, caring for, control burning, and keeping an eye on our prairie restoration remnant project. He also aids in the upkeep and care of our Prairie Putt-Putt mini-golf course during the summer months.

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Savanna Ellsbury-Reischauer

Vice President, Site Supervisor, & Vet Tech Student

Savanna Ellsbury graduated from Colo-NESCO High School alongside Jacobus and Kaleb in May of 2021. She was also voted onto the Board of Directors in March of 2021 and has recently been voted into the position of the Vice President of the Board of Directors in February of 2022.


Savanna is currently also attending Ellsworth Community College, but in pursuit of a Veterinarian Technician degree. Savanna is a site supervisor alongside Jacobus and helps in general upkeep, helping with the planning and cleaning the barn for events. 


Jacob & Savanna

Hannah graduated in December 2020 from Iowa State University with a Bachelor of Arts degree in Linguistics (the study of language) along with minors in Environmental Studies and Teaching English as a Second Language (TESL).  Graduating Magna Cum Laude but into a COVID job market, Hannah worked for one year at Center Grove Orchard as a warehouse manager, where she led a high school and college-age crew of helpers along with a crew of Hispanic workers that she interpreted and translated for. 

After a year of working for an income, Hannah was finally offered a job in her field of study that would begin her path to becoming an ESL instructor like she wanted to. After a year of working as the Interpretation & Translation Services Coordinator at Iowa International Center, Hannah received a job opportunity as an Adjunct ESL Instructor at DMACC. While loving her job at DMACC, she discovered that she was in need of a Master's degree in order to continue this job sustainably. 

Hannah is now attending graduate school at Iowa State University for the TESL/Applied Linguistics master's degree program in the hopes of collaborating in her time there and creating a curriculum and assessments surrounding teaching English as a second language with a focus on environmental language.


Through this program, she hopes to not only break down language barriers but also create a much-needed curriculum to teach students, adults, and all other ESL individuals that conversation and language surrounding environmental education and issues are much needed to ensure that, worldwide, we are having connecting conversations with our fellow humans about our world and its health. 

As the President of the Board of Directors, Hannah leads board meetings, aids in fundraisers, recruits new board members, and aids in coordinating events and future planning. She also helps wherever she is needed: Chaperoning our outbound trips, teaching our camps, programs, and classes, cleaning, helping cater for weddings, reunions, and graduation parties, working on the website and social media pages, and working hard on many of our manual labor jobs in keeping our nature center clean, cared for, and ready for visitors to have fun and bond with the natural world around them. 

Those Who Planted The Seed: The Universal Educators

Sharron Arnstedt Slinger and William (Bill) Slinger are retired educators with at least 60 years of teaching experience and experimentation between the two of them. Sharron taught English, Drama, and Spanish while Bill taught multiple Earth Science subjects. They traveled the United States teaching at multiple different schools, colleges, and outdoor education facilities. 

Bill and Sharron raised their children, Gretta, Jayson, and Karina,  with a focus on environmental ethics, the importance of a sense of adventure, and the great importance of a connection with nature and its benefits in education. As the parents of Owner and Executive Director, Gretta Reischauer, and grandparents of the Reischauer children, their influence on Threshold has been ever present from the day the organization was founded to the expansive natural escape and educational facility it is today. 

Now retired, they live on property as site supervisors, in the home that Mark Reischauer built for them out of a recycled grain bin (silo). They wanted to live close to their children and grandchildren while also being somewhere they could walk outside and enjoy a beautiful natural scenery for a morning coffee, afternoon reading break, or casual conversations with family and friends. The silo was a challenging but fun project for Mark and Sharron and Bill love to share it with many who come to visit and may even invite you in for a cup of coffee or an afternoon snack and chat.


With many years of wisdom and adventures from their life together, sitting down for a conversation with Sharron and Bill is always educational and entertaining. They are the universal educators and parents/grandparents to all that come visit and they are very much the reason Threshold Learning Center came to be and still continues today. 

Sharron & Bill
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Sharron Arnstedt Slinger

Board Secretary, Treasurer, & Site Supervisor.

Sharron Arnstedt Slinger is the mother of Gretta Reischauer and was a classroom English, Drama and Spanish teacher for nearly 25 years.


Many of the locals that attended and graduated from NESCO High School had Sharron as their English and/or Spanish teacher. These past students often praise her for her strict but loving way of teaching as it challenged them while also supporting and understanding them through their struggles.

She has been an administrative assistant at three outdoor education sites and has also been the Administrative Assistant to the Chaplain at Gustavus Adolphus College in Minnesota, much of the time following where her husband (Bill) was an educator at different times.


Sharron is the "glue" that keeps our organization together She can be found taking care of finances, schedules, publicity, dropping off camp and after school sign up sheets at schools, putting up flyers in post offices, general stores, gas stations, and anywhere they may be seen, and, finally, enjoying a good book in her chair just outside of her and Bill's silo home.


She also currently manages the Threshold Learning Center Facebook page where she keeps parents and locals updated with great pictures of camp kids having fun and outreaching posts for fundraising needs and events that are open to the public. 

Sharron is the board Treasurer and Secretary and, alongside her husband, encouraged and supported Threshold Learning Center and Gretta Reischauer from its initial stages to the wonderful connection it has become today. 

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William (Bill) Slinger

Board Member, Earth Science Educator, & Site Supervisor.

Bill is the father of Gretta Reischauer and has served as a longtime board member of the board of directors, spending much of his time on the board serving as either the president or vice president.


Bill Slinger was a classroom Earth Science teacher for over 20 years at several different schools and colleges. He has been in Outdoor Education for over 30 years and was a major component or ran at least 3 different major outdoor education facilities.  While at these facilities/organizations, Bill developed curriculum for middle school level students in Astronomy, Geology, and Archaeology.

At each of these camps, he also offered continuing credit education courses for teachers in Astronomy and Geology that were very well received. These courses encouraged educators to teach with more of a hands-on philosophy to help those students who may not be "Textbook" or "Standard Testing" learners.


Bill has supervised student teachers for Gustavus Adolphus College and Minnesota State University at Mankato and extended his influence and message of the importance of a hands-on or practical application of education.


Bill can be found tending our seasonal garden, planting new and caring for existing trees on the property, aiding in general maintenance and new projects, and overall offering an educated and experienced opinion on minor and major decisions for Threshold. 

Bill helps to develop our curriculum and teaches some of our programs including Geology, Astronomy, and other Earth Science camps and lessons.

Bill is cherished by his family and the many students and individuals who have come out to meet and learn from him. He is always ready to teach, talk casually, or listen and learn from  those who come out to visit at Threshold Learning Center.

The Others Who Have Helped Make Threshold Learning Center What It Is Today

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David Obrecht

Longtime Board Member

David Obrecht has been a long time board member and supporter of Threshold Learning Center. He has served as the President, Vice President, and Treasurer at multiple points in his time serving on the board of directors. 

David is very involved in the local community and whenever he has the time, outside of his own farming, he also serves on the local telephone company board of directors and has served with the Story County Soil and Water Conservation District. David has always been a forward thinking Iowan farmer that has been open to environmentally friendly practices for his farmland alongside his father Raymond Obrecht. 

Coming from a longstanding family of Iowa farmers, David has often supported Threshold by loaning large machinery that has been needed from time to time for new construction projects, basic maintenance, and clean up after major storms and natural disasters that we have faced. 

He has also helped with many maintenance and building projects over the years including the construction of the dormitory barn, the maintenance and laying of our rock driveway, the demolition of our old program center building, and the construction of our current program center. 

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Kaleb Ruffcorn

Board Member & Conservation Student

Biography To Be Added Soon!!!

David & Peggy
Other Board Members

Peggy Obrecht

Longtime Board Member

Biography To Be Added Soon!!!

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Carolyn Walker

Board Member & School Outreach

Biography To Be Added Soon!!!

Our Helpers Outside of the Board

Trip Crew

Our Loyal Trip Crew: Lilah Skaar, Ellie Shepherd, Jacobus Reischauer, Ryan Wonders, Trevor Burg, Benjamin Larsen, Kaleb Ruffcorn, Aydin Borden, and Lucas Olson. (Also Pictured Hannah Reischauer, Savanna Ellsbury and Megan Hulshizer)

Cameron Reischauer

Cameron Reischauer


Ava Haynes


Harrison Haynes


Allison Hulshizer


Kate Hulshizer

Bus and Megan

Jacobus Reischauer and Megan Hulshizer


Rachel and Sarah Phelan

Join Our Board Of Directors

     19 years.  That’s how long TLC has been offering outdoor experiences for people of all ages.  That’s how long it has taken for us to convert the site from an empty hayfield to a natural get-away with prairie, trees, a mini-golf course, a Memorial Arboretum, trails, a classroom, driveway, and barn dormitory.  That’s how long some of our Board Directors have been serving TLC and the community. 

     Our Board members have worked tirelessly trying to raise funds, trying to increase awareness and usage, cleaning, planting, building, mowing, and supporting me as we move forward in our mission.  Some were with us a short time, did great things, and moved on.  Some put in several years of support, hard work, and insight and left knowing that TLC was a better organization because of their service.  Some left TLC and this world much too early.  We NEVER would have been able to get as far as we are without each and every one of them.  They have also paved the way to make being a Board Member easier and less demanding.  The big projects are done.  The demands of showing up every weekend ready to work are over. 

     This year at our Annual Meeting a few more of our Board members are opting to leave and pass the torch on to others.  We are in need of at least 4 more members.  If you are interested in helping TLC reach its next set of goals, or you think it is a great organization and feel you have a lot to offer, please consider joining us.  There is not that much involved with being on the Board of Directors.  We have around 6 meetings each year that usually coincide with a work day where we accomplish some of the site needs or tend to our gardens or trails.  Help at big events, like our annual Fall Festival in October, is appreciated as well.  Finally, we ask that you take on one thing that’s “your baby”, whether it’s a fundraiser, a project that needs to be completed, grant writing, cleaning, whatever you decide that will fit into your schedule or abilities.

     We would LOVE to have you join our Board!  We seriously need more help and could always use a new look at what we do.  If you are interested, you can contact us at with any questions.  

Join The Board
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