2012 Lake Dredging Project
DMACC LAKE DREDGING PROJECT
This project is removing 52,000 cubic yards of sediment that has accumulated in the DMACC lake over the last 30 years. Deepening the DMACC Lake by an average depth of overfive feet will improve water quality, improve angling opportunities, and create a more aesthetically pleasing water resource. This project will remove sediment that has degraded DMACC Lake by creating shallow water conditions. Shallow lakes are prone to internal nutrient loading and contribute to large algae blooms in the lake each summer. Removing the sediment will decrease the concentration of phosphorous, nutrients, and suspended solids; and improve water clarity and oxygen levels.
Previously completed upstream watershed improvements are treating storm water runoff. The upstream has been stabilized and reduced bank erosion caused by runoff from urbanized land north of campus and east of Highway 69 that drains into the DMACC Lake. DMACC is treating this runoff with several best management practices that include, rime dams, stream bank protection, a forebay to trap sediment, bioswales, vegetative filters, wetlands, vortech device, and native prairie grasses and wild flower filter strips.
DMACC Lake Watershed
DMACC LAKE WATERSHED
Rain water falling on this watershed drains into the DMACC lake. People who live or work within the DMACC lake watershed area can decrease the sediment and pollutants that reach DMACC lake by using storm water management and erosion control practices. For more information on how you can reduce runoff and sediment reaching DMACC lake, please contact the Polk Soil and Water Conservation District in Ankeny or on the web at www.polk-swcd.org.
Rainfall often runs off roofs, sidewalks, driveways, streets, and compacted lawns; and flows into the street, through the storm sewer to the nearest stream, river, or lake. Along the way it picks up pollutants, such as fertilizer, grass clippings, sediment, pet waste, oil, bacteria, and more. You can help prevent these pollutants from reaching storm drains and streams by incorporating beautiful rainscaping practices into your landscape. Rainscaping practices include rain gardens, soil quality restoration, permeable pavements, native landscaping, rainwater harvesting, and the watershed practices that DMACC incorporated in to the campus in 2011. So don't just landscape, rainscape. More information on how to 'rainscape' your property is available on the web at www.rainscapingiowa.org.
Watershed Improvements Completed in 2011
COMPLETED PROJECTS SHOWN ABOVE:
Bioswales convey surface runoff while helping to filter and absorb the water. The soils and rock under the bioswale promote infiltration of the water into the ground. Native Iowa plants in the boiswale with deep roots increase the filtering and in filtration of bioswales, and reduce the amount of runoff that flows through directly to the lake.
Creek Improvements were installed to stabilize slopes and reduce erosion that caused sedimentation in DMACC lake. This work included grading, armoring, riffle dams, and native plantings.
The Forebay was constructed to provide a place for sediment to drop out of the water coming from the stream. The concrete wall slows the flowing water, reducing the sediment entering DMACC lake.
Native Plantings slow and filter runoff water that drains into DMACC lake. Native plantings soak up more water than turf grass lawns and attract desirable wildlife.
Structure Changes include updates to storm water intakes to better handle water runoff during rain events.
The Vortech is an underground structure that is a hydrodynamic separator that removes sediment and debris from runoff.
The Wetland intercepts surface water runoff reducing sediment and pollutants that enter DMACC lake.
DMACC would like to thank the following partners who are assisting the college with this project:
- Iowa Department of Natural Resources Fisheries Bureau
- Polk Soil and Water Conservation District
- Polk County
- USDA Natural Resources Conservation Service
- Iowa Department of Agriculture and Land Stewardship