Katherine Mueller began her career in nonprofit development in 2006 in the Twin Cities. After gaining experience at organizations like Dress for Success Twin Cities and Tree Trust, she moved to Duluth in 2015 to fill the Development Director role at the Damiano Center. She launched Flourish Nonprofit Development LLC in 2020 primarily to meet the needs of small and start-up organizations that could not support full-time development staff.

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​Katherine has a BA in English and Philosophy from Albion College and nearly 20 years of experience in nonprofit resource development, communications, and financial management. She has worked with nonprofits that provide children's and youth services, employment training, housing, education, basic needs, environmental programs, and more. These include established nonprofits as well as start-ups, private foundations, and intermediary organizations. She has also served as a grant reviewer for various entities, including the MN State Arts Board and St. Louis County Family Homeless Prevention and Assistance Program.

 

Katherine believes that whole communities can flourish when they have a highly functioning and interconnected system of nonprofits, government agencies, businesses, foundations, and community members. Learn more about Katherine's experience by visiting her LinkedIn profile.

Tammy Sundbom, CFRE, is an accomplished Development, Marketing, and Communications professional with over 25 years of experience across nonprofits, marketing, publishing, and healthcare. She currently serves as a Public Policy Advisor for MN Power/Allete, and joined Flourish part-time as a consultant in 2024.

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Previously, Tammy spent over six years as Chief Development Officer for the Boys & Girls Clubs of the Northland, where she significantly increased fundraising revenue, launched a nationally recognized mental health program, and enhanced the organization's community profile. Passionate about youth development and education, Tammy actively contributes to several community organizations. She chairs the Program Committee for the Rotary Club of Duluth #25 and has held leadership roles such as Fundraising Director for the Twig Amateur Hockey Association and Board Member for Proctor Youth Softball Association. An enthusiastic coach, Tammy has had the joy of coaching youth in golf, baseball, softball, soccer, and basketball.

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Tammy holds a Bachelor of Arts in Journalism and Advertising with a minor in Business Administration from the University of St. Thomas in St. Paul, MN. She is also a Certified Fundraising Executive (CFRE), demonstrating her commitment to the highest standards of ethics and professionalism in fundraising. In her free time, Tammy enjoys biking, golfing, boating and just getting outside in our beautiful area with her four children, family, and friends. Learn more about Tammy's experience by visiting her LinkedIn profile.

Sarah Mueller-Johnson has more than 15 years of experience in a variety of administrative, customer service, and financial roles. She provided member services at Embers Credit Union for more than ten years after attending Northern Michigan University. In this role she developed strong customer service, administrative, and financial management skills. 

 

She has worked part-time as a property manager since 2020, managing all elements of the business including scheduling, maintenance, customer service, and bookkeeping. Sarah is process-oriented, organized, and has strong attention to detail. These skills serve her well as she coordinates and supports clients' projects, and she joined Flourish part-time in 2025.

 

Sarah values her part-time schedule and flexibility to spend time with her family. She lives with her husband and two children in Marquette, MI, where she enjoys outdoor activities like running, swimming, biking, and hiking. ​