I copied this from SculptureWalk’s sponsor page:
Sponsors
SculptureWalk is a volunteer organization that raises approximately $70,000 in private funds from site sponsorships, memberships, and sales commissions.  All expenses are paid from the private funds. SculptureWalk is a program of the Sioux Empire Arts Council a 501(c)3 non-profit organization, and all contributions are tax-deductible as allowed by law. The City of Sioux Falls contributes $25,000 annually to purchase the People’s Choice Award sculpture and quartzite and concrete pedestals for the sculptures.
http://www.sculpturewalksiouxfalls.com/sponsors/
Most of this information is true, but some information has been conveniently left out.
1) SW has a city representative. I would assume if they are attending SW meetings during their regular work schedule they are on the clock. So that would make SW not entirely volunteer.
2) (I think) The city also contributes liability insurance (which is good) this is how it was originally done because it is cheaper for the city to cover it as a blanket policy then for SW to buy it individually and since the sculptures are placed on city owned property they are liable for any accidents involving the sculptures.
3) SEAC also receives a subsidy from the city, so any contribution from SEAC to SW, has public money intertwined in it. In the SW brochure it mentions grants from The Community Foundation and The SD Arts Council, both organizations that receive public money also.
SculptureWalk’s biggest argument for keeping the public out of the loop on decisions is because of the private funds. But as you can tell, by their own admission, the public gives quite a bit, and should be allowed to participate.
I’ve dubbed this year’s SW, “The Revenge of the Animal Crackers”