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Home / Projects / Oasis Pond Iron-Enhanced Sand Filter

Oasis Pond Iron-Enhanced Sand Filter


Roseville, Minnesota

Completion Date






Water Body

Little Lake Johanna, Ramsey County Ditch 4 (RCD 4)

Funding Sources

Clean Water Fund Grant, Rice Creek Watershed District



RCWD was awarded a $280,000 Clean Water Fund grant from the Clean Water, Land, and Legacy Amendment to design and install a pump-operated iron-enhanced sand filter (IESF) in Roseville’s Oasis Park. These innovative filters utilize a combination of iron and sand to effectively remove pollutants from water sources. By targeting contaminants such as phosphorus, sediment, and other harmful substances, these filters play a crucial role in reducing water pollution. 

The system diverts runoff from the Ramsey County Ditch 4 (RCD 4) drainage system and removes phosphorus, sediment, and other pollutants before discharging the cleaner water back to RCD 4. 

The project is expected to reduce phosphorus loading to downstream Little Lake Johanna by 34 lbs. annually. Roseville has been an active partner on this project and provided the land necessary for RCWD to construct the new IESF. Roseville is also volunteering to provide ongoing operation and maintenance of the system.

RCD 4 carries stormwater runoff from a large urbanized area – including the Rosedale Mall complex – to Little Lake Johanna and Lake Johanna downstream. The location of this project was ideal because RCWD already owned and operated a sediment basin and outlet weir on Oasis Pond.

The cost of this project was $322,520. Funded by a Clean Water Fund grant of $258,016, $54,504 from RCWD, and $10,000 from the City of Roseville.

To Learn More Contact:

Matt Kocian

Lake & Stream Manager