Citizens asked at the first annexation meeting how they could try to protest or stay out if the city tried to forcibly annex them in.  A reader also asks this on your blog. Here is the answer Councilor Neitzert I was able to get.
If a landowner or group of them object to a FORCED annexation (city initiated) they have a few legal options (three specifically below).
1.  Put the resolution of annexation passed by the city council on the ballot.  This would be very similar to what happened with Walmart, Shape Places, and almost with the administration building.  The only difference is the 5% of registered voters who have to sign the petition are the sum of all of those in Sioux Falls plus all of those in the newly annexed area, so if there were 120,000 registered Sioux Falls voters, and 100 registered voters in a newly annexed area, there would need to be 5% of 120,100 registered voter signatures on a petition collected by 20 days after publication of the resolution.  That would put the question on the ballot and there would have to be an election.  That process is explained here:
SDCL 9-4-4.5.   Petition for submission of annexation resolution to voters. The required number of voters residing in the combined area of the municipality and special annexation precinct may file within twenty days after the publication of the annexation resolution a petition with the municipal finance officer, requiring the submission of the annexation resolution to a vote of the voters of the combined area of the municipality and special annexation precinct for its rejection or approval.
SDCL 9-4-4.6.   Contents of referendum petition–Signatures–Verification. The petition shall contain the title of the resolution or the subject of the resolution and the date of its passage. The petition shall be signed by at least five percent of the registered voters residing in the combined area of the municipality and the special annexation precinct established pursuant to § 9-4-4.8. The percentage shall be based on the number of voters in the municipality at the last preceding general election. Each voter shall add to the voter’s signature the voter’s place of residence, including street and house number, if any, and the date of signing. The referendum petition shall be verified in the same manner as a petition to initiate a law except that the person verifying shall state that each person signing the petition is a resident and registered voter of the municipality or special annexation precinct. No signature on the petition is valid if signed more than six months prior to the filing of the petition.
2.  After a resolution to annex goes into effect, and a group is now IN the city, they can attempt to petition OUT.  Note that this is NOT the same as a zoning protest petition where a group of landowners can force the council to revote on the same ordinance (like the Brett apartment rezone).  This is after the original resolution has passed and gone into effect.  If there were 75% of landowners of equity and registered voters of a block that was annexed, they can force the council to vote on a resolution to exclude (remove) them from the city.  That vote is a simple majority vote of the council.  If the council does not vote to remove them from the city, state law says they can bring that to circuit court (see SDCL 9-4-8 and 9-4-9 below).  Another way to take a group out of the city is by a two-thirds vote of the city council, which would be unlikely if they had just forcibly annexed the same group.
SDCL 9-4-6. Exclusion of territory from municipality on petition or by vote of governing body
Upon a two-thirds vote of the governing body, or on petition in writing signed by not less than three-fourths of the legal voters and by the owners of not less than three-fourths in value of the property in any territory within any municipality being upon the border thereof, the governing body may by resolution exclude the territory from the municipality. However, if all the land sought to be excluded is more than one-half mile from any platted portion of the municipality, the petition must be signed by the owner only.
SDCL 9-4-7. Publication of petition for exclusion of territory
No final action shall be taken by the governing body upon any petition presented in pursuance of the provisions of § 9-4-6 until notice of the presentation of such petition has been given by the petitioners by publication at least once each week for two successive weeks.
SDCL 9-4-8. Petition to circuit court for exclusion of territory after refusal by governing body
Upon the failure of the governing body to grant the request contained in a petition presented in accordance with the provisions of §§ 9-4-6 and 9-4-7, for thirty days after the last publication of the notice or upon a refusal to grant such request, the petitioners may present their petition to the circuit court of the county in which such municipality or the greater portion of it is situated, by filing such petition with the clerk of courts.
SDCL 9-4-9. Service of notice of petition to circuit court–Hearing at term or in vacation
Notice of filing pursuant to § 9-4-8 shall be served by the petitioners upon the mayor or president of the Board of Trustees, as the case may be, together with a notice of the time and place when and where a hearing will be had upon such petition, at least ten days before the date of such hearing.
The hearing on the petition may be had by the court at a regular or special term or in vacation.
SDCL 9-4-10. Court order for exclusion of territory–Dismissal of petition
If upon the hearing the court shall find that the request of the petitioners ought to be granted and can be granted without injustice to the inhabitants or persons interested, the court shall so order.  If the court finds against the petitioners, the petition shall be dismissed at the cost of the petitioners.
3.  Some other sort of action in circuit court objecting to some legal aspect of the forced annexation or the process in which it was done.

By l3wis