Floods of 2008: How Did Aquatic Life in Streams Fare?

Summary of biological water quality data collected during the Floods of 2008.

Biological Assessment of Iowa's Wadeable Streams, October 2004

The TMDL and Water Quality Assessment Section of the Iowa DNR Environmental Services Division have released the report entitled, “Biological Assessment of Iowa’s Wadeable Streams.” The report describes a framework for conducting stream bioassessments and how it is used to evaluate the biological condition of Iowa’s wadeable rivers and streams. The document also serves as a foundation for developing biological water quality standards for the protection of designated aquatic life uses and measuring progress toward the achievement of Federal Clean Water Act goals.

Muchakinock Creek: Improving Water Quality for the Future, 2005

History has taken its toll on Muchakinock Creek. A number of problems over the years have led to the stream’s current state, one that’s landed it on Iowa’s list of impaired waters. However, the stream is also full of opportunity. The opportunity to improve water quality not only for the aquatic life and wildlife that live there, but also to pass along clean water to future generations of Iowans. But to act on this opportunity, we need your help.

Repairing the Impaired: Two Iowa Success Stories, 2005

More than 200 lakes, streams and rivers are on Iowa’s impaired waters list. Pollutants prevent these waters from supporting aquatic life, or from being used for drinking water or for full body recreational contact, like swimming. While improving Iowa’s water quality may seem a daunting task, two southern Iowa lakes show that it can be done.

Brushy Creek Lake: Improving Our Lake for the Future, 2006

While the quality of water in Brushy Creek Lake is currently adequate, a number of factors in the watershed (the surrounding area that drains into the lake) could put that water quality at risk. Sediment from the large watershed could fill in the lake and affect water clarity. Nutrients, like nitrogen and phosphorus, could cause algae blooms and other problems. Without preventative measures, potential manure and chemical spills could harm aquatic life in the lake. Using conservation farming practices and building structures like wetlands will work to maintain and even improve the lake’s water quality. Taking steps now to implement these critical practices will help prevent water quality problems, preserving water quality for future generations.

Design Procedures and Field Monitoring of Submerged Barbs for Streambank Protection, June 2007

The main objective of this study was to evaluate the hydraulic performance of riprap spurs and weirs in controlling bank erosion at the Southern part of the Raccoon River upstream U.S. Highway 169 Bridge utilizing the commercially available model FESWMS and field monitoring. It was found based on a 2 year monitoring and numerical modeling that the design of structures was overall successful, including their spacing and stability. The riprap material incorporated into the structures was directly and favorably correlated to the flow transmission through the structure, or in other words, dictated the permeable nature of the structure. It was found that the permeable dikes and weirs chosen in this study created less volume of scour in the vicinity of the structure toes and thus have less risk comparatively to other impermeable structures to collapse. The fact that the structures permitted the transmission of flow through them it allowed fine sand particles to fill in the gaps of the rock interstices and thus cement and better stabilize the structures. During bank-full flows the maximum scour hole was recorded away from the structures toe and the scourhole size was directly related to the protrusion angle of the structure to the flow. It was concluded that the proposed structure inclination with respect to the main flow direction was appropriate since it provides maximum bank protection while creating the largest volume of local scour away from the structure and towards the center of the channel. Furthermore, the lowest potential for bank erosion also occurs with the present set-up design chosen by the IDOT. About 2 ft of new material was deposited in the area located between the structures for the period extending from the construction day to May 2007. Surveys obtained by sonar and the presence of vegetation indicate that new material has been added at the bank toes. Finally, the structures provided higher variability in bed topography forming resting pools, creating flow shade on the leeward side of the structure, and separation of bed substrate due to different flow conditions. Another notable environmental benefit to rock riprap weirs and dikes is the creation of resting pools, especially in year 2007 (2nd year of the project). The magnitude of these benefits to aquatic habitat has been found in the literature that is directly related to the induced scour-hole volume.