SIOUX FALLS, S.D. (AP) — Officials say initial lab tests indicate that a wastewater spill into the Big Sioux River will not affect people or wildlife.

Sioux Falls Public Works officials say they're continuing to monitor the river and expect more test results later in the week.

The city in a statement says about 9,000 gallons of "treated biosolids" made it into the river Sunday before the spill at the water treatment plant was contained. Wastewater Superintendent Mary Perry classified the amount as "fairly minimal."

Perry did not immediately respond to a request for more information early Monday.

The contractor responsible for the spill — Veit of Rogers, Minnesota— is working to clean up the spill area. That's expected to take several days.

Copyright 2014 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.