Addressing Water Quality Concerns
As of 2014, the Iowa Department of Natural Resources (DNR) listed 572 bodies of water as impaired, which has garnered strong publicity with Iowans becoming increasingly concerned about water quality. Common pollutants include nutrients, sediment, and chemicals. While the majority of Iowa waters are only impaired on a minor to moderate level, now is the time to act before the issue grows in severity.
One area of concern is the Des Moines River because it serves as a primary water source for numerous communities within the Des Moines River watershed. It’s also a popular recreation destination for anglers, water sports enthusiasts, and people who enjoy the beauty of rivers. At approximately 525 miles long, it’s also the largest river in Iowa and a tributary of the Mississippi River.
Due to bacteria levels, it was identified as impaired in Iowa’s 2012 Integrated Report: Category 5: EPA-Approved Section 303(d) Impaired Waters. Recognizing opportunities to restore the original beauty and function of the Des Moines River, the City of Fort Dodge has dedicated a large part of its comprehensive plan to improvement efforts.
Restoring River Beauty & Function
Water quality improvement objectives include:
- Improving the integrity of the river by preventing future degradation
- Restoring natural in-stream habitat conditions
- Meeting the designated uses for the river
Central to the project is the removal of the Fort Dodge Hydroelectric Dam and a smaller dam, known as Little Dam, which lies two miles south. Constructed in 1916, the Fort Dodge Hydroelectric Dam generated electricity for downtown street lights until 1971 when it was decommissioned. It has since been abandoned, with subsequent gate failures contributing significantly to the decline in water quality.
Studies completed in 2006 and 2010 both concluded that redevelopment of the dam for hydroelectric power was not economically feasible. In the summer of 2016, the deteriorating power plant building next to the Hydroelectric Dam and its gates were removed.
As part of the Des Moines River and Lizard Creek Water Trails and Corridor Plan, both the Hydroelectric Dam and Little Dam were recommended for removal in order to restore the natural flow of the river while improving water quality and safety for kayaking and other recreational uses.
Dam removal is only part of the overall plan to improve water quality, restore in-stream habitat, and meet the river’s designated use. Since the project began, we’ve completed several tasks as part of a fluvial geomorphological assessment:
- Bathymetric survey to determine river geometry and provide insight on the depth and shape of underwater terrain
- Depth of refusal probing to quantify the volume of silty material located upstream from each dam
- Cross-sectional survey to develop a profile of the river
- Wetland and stream delineation as required by the U.S. Army Corps of Engineers (USACE) and Iowa DNR
- Threatened and endangered species reviews
- Preliminary deconstruction plans and cost estimates
- Coordination with the USACE, U.S. Environmental Protection Agency, and Iowa DNR
- City Council workshops and presentations
During a recent City Council workshop, Snyder staff unveiled options for in-stream structures that will provide water quality and ecological benefits as well as regional recreational benefits. Options include the construction of a j-hook with benefits to streambank stabilization and a fishing structure near the current location of the Hydroelectric Dam, or rock crest weirs that support whitewater recreation in locations to be determined.
Noteworthy items from recent fieldwork include:
- Sediment probing completed above both the Hydroelectric and Little Dam to determine sediment loading quantities in the river showed a maximum sediment depth of 9.5-feet for the Hydroelectric Dam and no sediment for the Little Dam.
- Bedrock outcroppings, or locations where bedrock is visibly exposed, were observed along the length of the studied segment. The area above the dam had the most outcroppings.
- Logjams were found to be quite common below the Little Dam, with none noted elsewhere within the studied segment.
Future work includes:
- Permitting with the Iowa DNR and USACE
- Final design to include final stream mitigation amenities and dam removals
- Destruction and removal of both dams and a concrete wall on the western riverbank near the Hydroelectric Dam
“It’s going to take time, but we’re confident this plan will improve water quality of the Des Moines River and improve water recreation for the region.” — Jeff Walters, Environmental Scientist, Snyder & Associates.
”I think this is going to be a great improvement in the condition of the river.” – Terry Moehnke, Fort Dodge City Councilman.
“This project is going to make significant environmental and recreational improvements to the river. The community and river users are going to enjoy new fishing and boating along this stretch of the Des Moines River.” – Nichoel Church, Environmental Scientist, PWS, Snyder & Associates.