Clarke County Soil & Water Conservation District

West Lake (320 surface acres) is the water supply for the city of Osceola (pop. 4,659) and the surrounding region. It has a drainage area of 6,400 acres and is listed on the EPA’s Section 303(d) list with low levels of dissolved oxygen and organic enrichment identified as the impairments. A monitoring effort was initiated in 2012 to associate trends of the low levels of dissolved oxygen and possible causes. A Total Maximum Daily Load (TMDL) has been written for the corn herbicide atrazine. Springtime runoff spikes of atrazine that exceed the drinking water standards still occur, indicating that atrazine continues to be a concern.  West Lake has been identified through a series of public meetings as being the highest priority for EQIP funding.

 

Approximately 15,000 acres of Clarke County farm ground drain into Rathbun Lake. Water from this reservoir is used by the Rathbun Rural Water Association to supply one of the nation’s largest rural distribution systems. Sediment delivery to the lake caused by sheet and rill erosion is the primary resource concern in this watershed.

 

The City of Osceola is anticipating that it will experience water quantity problems in the future. The planning process to identify a potential lake site on Squaw Creek in the northwest part of the county was initiated in 2004 and is nearly complete. This lake will be used along with West Lake to provide an additional water supply to the city of Osceola as well as the surrounding area.  Sediment delivery from sheet, rill and gully erosion are expected to be the primary resource concerns for this proposed lake.

 

The Whitebreast Creek Watershed in Clarke County (60,400 acres) is the upper portion of a 276,000 acre watershed that drains into Lake Red Rock. Whitebreast is thought to be one of the major contributors of sediment to Lake Red Rock therefore; soil conserving practices that prevent sediment delivery to the stream will be the primary emphasis in this watershed. A portion of the main channel is on the Iowa 303(d) Impaired Waters Listing with aquatic life identified as being impaired. Habitat alterations, sedimentation and low dissolved oxygen levels are thought to be the likely causes/stressors.

 

East Lake (320 acre drainage area), a small county owned lake located near Osceola is also in the Whitebreast Watershed. East Lake is included on the Iowa Section 303(d) Impaired Waters listing with primary contact (recreation) identified as impaired. Turbidity and aesthetically objectionable conditions contribute to this impairment.