Decision time is quickly approaching for the future of the leaking, aging Mitchell Park Domes

The Mitchell Park Domes continue to deteriorate — old window glazings leak water in storms while concrete support pillars crumble — and the popular horticultural conservatory will close within a few years unless $30 million is found to do just basic repairs, a citizen task force says.

Or Milwaukee County could upgrade the domes at an estimated cost of $95 million with canopy walks, zip lines, butterfly exhibits, an outdoor children's garden, and other adventure or ecological science features to pull in more visitors and more revenue.

Each investment would buy only 25 more years of life for the three domes, home to the county's horticultural conservatory.

Those options are among several possible choices for the future of the domes to be discussed Tuesday at a public hearing beginning at 6 p.m. in the conservatory's lobby entrance, 524 South Layton Boulevard.

No one disputes that money is needed to keep the domes open.

In heavy downpours on June 18 and 19, "it was raining in all three domes," said Sally Sullivan, executive director of the Friends of the Domes, a support group.

Sullivan has reminded the task force that an analysis of the concrete pillars to be done this year could conclude the support structures cannot be repaired.

For that reason, replacing all three domes with a new structure — such as the cylindrical Crystal Bridge Conservatory in Oklahoma City or Amazon Spheres in Seattle — should be considered by the task force, even though that is not among their selected options for public comment, Sullivan said.

Milwaukee's unique conoidal domes —  described as a beehive or half an egg — were constructed between 1959 and 1967 and each dome is more than 50 years old.

After stainless steel wire mesh was wrapped around the pillars of each dome in 2016 to prevent concrete chunks from falling on visitors or employees, the task force was named to recommend a future for the three domes sitting atop the south edge of the Menomonee Valley. No work was done on the windows at that time.

The 2016 mesh fix was expected to last no more than five years, said county engineers, before more work would be needed to keep the domes open. Time runs out in three years.

Doing nothing more than replacing the wire mesh might buy five more years for the aging domes but the support structure and windows would continue to deteriorate and the task force acknowledged this option would end in demolition, said chairman Bill Lynch, a retired attorney.

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There is little support in the community for that "do nothing" option, Lynch said.

After hearing public comments at Tuesday's meeting, the task force will meet July 10 to pare down the list of options to two or three.

After results are in this year from the analysis of concrete support columns and a separate analysis of windows and glazing, detailed cost estimates will be done on the remaining two or three options.

Then the task force might study the feasibility of raising tens of millions of dollars for the project before recommending one option to County Executive Chris Abele and the County Board.

Limited dollars

A discussion of what can be done with the domes, or even the possible construction of a new conservatory to house its tropical and desert plant collections, comes at a time when planning is well underway for other costly public and private facilities in the county.

"There will be a lot of competition," Lynch said.

Among the highest priced individual projects are relocating the Milwaukee Public Museum at a cost of more than $100 million and building a $262 million county criminal courthouse. Total criminal courthouse project costs climb up to $367 million if you include demolition of the current Safety Building and relocation of criminal court services during construction.

And the county is facing in excess of $246 million in deferred maintenance at its parks and parkways, officials said.

Apart from doing nothing for the domes, the task force will provide information on the following options at the Tuesday meeting:

Demolish the domes. But have the county keep greenhouses and the annex. Apart from losing 200,000 or so visitors each year, the county would spend up to $15 million to landscape the west end of the park, transfer plants to other suitable homes and develop new uses for the greenhouses and annex.

Deferred maintenance. The county would spend up to $30 million on basic repairs to glass panes and concrete pillars and bring domes into compliance with current building codes and accessibility requirements.

Limited repairs and investments. It would cost up to $50 million for deferred maintenance and classrooms, meeting spaces, a new visitors entrance, upgrades to retail space and food service, adding a catering kitchen to annex and expanding parking.

EcoDome. The county would spend up to $95 million on basic repairs, change the Show Dome to an Ecological Habitat Zone with canopy walks and aquariums, add a butterfly exhibit, outdoor children's garden and a full-size restaurant.   

Adventure Dome. Up to $95 million would be spent on basic repairs and changing the Show Dome to a themed Adventure Experience with canopy walk. This option would include a zip line, climbing structures, a butterfly exhibit, outdoor children's garden and full-size restaurant.  

Demolish Show Dome. The plan includes repairing the other two domes. The county would spend up to $95 million on repairs to the Tropical and Desert domes and build a replacement structure for an EcoDome or Adventure Dome.

The Friends of the Domes added another option of replacing all three domes with a new structure.

"We don't know for sure that preservation is an option and it might be more expensive than building new," Sullivan said. "We're trying to stay neutral in this and present all options to the public."