DES MOINES, Iowa (AP) — Most of 30 protesters arrested last month at a central Iowa petroleum pipeline construction site have appeared in court on a trespassing charge.

All but one took responsibility and will pay just over $270 in fines and fees. One pleaded not guilty and faces trial.

The protesters are members of environmental and citizens actions groups. They rallied Thursday after court appearances. They’re calling on President Barack Obama to halt the Dakota Access pipeline claiming it will harm water supplies and disturb American Indian burial and cultural sites.

The Standing Rock Sioux Tribe in North Dakota and property owners in Iowa are suing to stop the project.

Pipeline supporters say half the pipeline is completed and stopping it now undermines the regulatory process and chills future infrastructure projects.