Cooperative Lakes Area Monitoring Project-East Okoboji Lake, 2007

Water fact sheet for Iowa Department of Natural Resources and the Geological Bureau.

Pilot Knob State Park, Merrick State Park, Eagle Lake State Park, Rice Lake State Park and Crystal, East and West Twin, and Duck Lakes,1925.

Provides information on Pilot Knob State Park, Merrick State Park, Eagle Lake State Park, Rice Lake State Park and Crystal, East and West Twin, and Duck Lakes including history, maps, location, terrain, photos, vegetation and wildlife.

Flood of June 15-17, 1998, Nishnabotna and East Nishnabotna Rivers, Southwest Iowa, HR-140

Record flooding occurred June 15-17, 1998, in the Nishnabotna and East Nishnabotna River basins following severe thunderstorm activity over southwest Iowa. More than 8 inches of rain fell over a large part of Cass County. The rain gage at Atlantic, Iowa recorded a 24-hour total rainfall of 13.18 inches, which established a new official State record for the greatest amount of rainfall in a 24-hour period. The peak discharge was 41,400 cubic feet per second in the East Nishnabotna River near Atlantic, 60,500 cubic feet per second in the East Nishnabotna River at Red Oak, and 65,100 cubic feet per second in the Nishnabotna River above Hamburg. The peak discharge at Atlantic was greater than the theoretical 200-year flood and the peak discharges at Red Oak and Hamburg were greater than the respective theoretical 500-year floods. Information about the basin, the rain storms, the flooding, and a profile of high water marks at selected intervals along the Nishnabotna and East Nishnabotna Rivers are presented in this report.

08006-003 East Okoboji Beach Final Report

East Okoboji Beach was platted on April 20, 1961 and includes over 90.4 acres with 489 lots. The East Okoboji Beach project includes a complete storm water discharge system, which includes low impact development and reconstruction of the roadways in East Okoboji Beach. The East Okoboji Beach Project is an enormous project that is the first Dickinson County project to retrofit LID practices, lake-friendly storm-water drainage systems and roadway reconstruction throughout an existing sub- division. This cooperative project between DNR, Dickinson County, and EOB landowners includes engineering retention ponds, rain gardens, bio-swales and other LID practices to reduce nutrient and sediment pollutants flowing directly into East Okoboji. The nature of the problem stems back to that original plat where small lots were platted and developed without planning for storm water discharge. There was no consideration of the effects of filling in and developing over the many wetland areas existing in EOB. The scope of the problem covers the entire 90.4 acres in East Okoboji Beach, the DNR owned land and the farmed land to the east. The nature of the problem stems from storm water runoff flowing throughout the watershed and into East Okoboji Beach where it flows down self-made paths and then into East Lake Okoboji. That storm water runoff dumps nutrient and sediment pollutions directly into East Lake Okoboji. The expected result of this project is a new roadway and drainage system constructed with engineering that is intended to protect East Lake Okoboji and the land and homes in East Okoboji Beach. The benefit will be the improvement in the waters and the reduction of the siltation in the East Lake Okoboji.

East 1 St Street Interchange and I-35 Widening, From MP 94.3 to Oralabor Road, Polk County, Iowa, Project # IM-035-4(140)92--13-77, Environmental Assessment and Section 4(f) De Minimis Impact Finding, 2015

From Proposed Action: "The proposed action consists of reconstructing the East 1st Street/I-35 interchange with a Diverging Diamond interchange, widening I-35 from four (4) lanes to six (6) lanes, and widening East 1st Street from four (4) lanes to five (5) lanes from Delaware Avenue to Frisk Drive. The project also proposes to reconstruct the intersections of East 1st Street/Creekview Drive and East 1st Street/Frisk Drive."

Road Safety Audit for County Road X-37, from the Intersection of G-62 to the East Corporate Limits of Columbus City in Louisa County, Iowa, 2009

A road safety audit was conducted for a 7.75 mile section of County Road X-37 in Louisa County, Iowa. In 2006, the average annual daily traffic on this roadway was found to be 680 vehicles per day. Using crash data from 2001 to 2007, the Iowa Department of Transportation (Iowa DOT) has identified this roadway as being in the highest 5% of local rural roads in Iowa for single-vehicle runoff- road crashes. Considering these safety data, the Louisa County Engineer requested that a road safety audit be conducted to identify areas of safety concerns and recommend low-cost mitigation to address those concerns. Staff and officials from the Iowa DOT, Governor’s Traffic Safety Bureau, Federal Highway Administration, Institute for Transportation, and local law enforcement and transportation agencies met to review crash data and discuss potential safety improvements to this segment of X-37. This report outlines the findings and recommendations of the road safety audit team to address the safety concerns on this X-37 corridor and explain several selected mitigation strategies.