Impact of Dam-Reservoir Systems on Wetlands with an emphasis on John Redmond Reservoir

Elizabeth Hagenmaier, Sophia Mingoia, and Nicholas Worthen

Spring 2016 ES341/767 Wetland Environments
Dr. James S. Aber, Instructor

Table of Contents
Impact on biodiversity
Altered carbon cycle
Alteration of plant life
Dam Operation and Maintenance
Comparison to Melvern Lake

Wetland Survey for John Redmond Reservoir USFWS

National Wetlands Inventory of John Redmond Reservoir on aerial map provided by ESRI. Map created by author Mingoia on April 22, 2016 from the

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Over 48,000 large dams are in operation worldwide while several tens of thousand more operate on a smaller scale. They are built for hydroelectric power, drinking water sources, irrigation, flood prevention, etc. A WWF report identified that over 60% of the world's 227 largest rivers have been impacted by dams. This fragmentation of the rivers have led to a decline in freshwater species, displacement of human populations, and the destruction of wetlands. (WWF, 2016) Dams have been used extensively throughout the United States with several in the state of Kansas.

The John Redmond Dam and Reservoir is located on the Neosho River, approximately two miles northwest of Burlington, Kansas and about 22 miles southeast of Emporia, Kansas. Construction began in 1959 and was completed in December 1965. It is used for flood control, water supply, water quality control and recreation. John Redmond Dam is an earthfill embankment and a gated ogee weir, concrete spillway that rises to a maximum height of 86.5 feet above the streambed. The dam is 21,790 feet long including all components. John Redmond Dam and Reservoir was constructed in response to the frequent flooding of the Neosho River valley, 57 times in 34 years (USACE, n.d.). The benefits of dam-reservoir systems, like John Redmond, may no longer outweigh the negative environmental impacts, specifically the impacts to wetlands.

Spillway of John Redmond Reservoir USACE

Spillway at John Redmond Dam and Reservoir. Image from USACE. (USACE, n.d.)

Wetland Survey on Topo for John Redmond Reservoir USFWS

National Wetlands Inventory of John Redmond Reservoir on topographic map provided by ESRI.
Map created by author Mingoia on April 22, 2016 from the

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Impact on biodiversity

Natural rivers, including their riparian zones, belong to the most dynamic, diverse and complex ecosystems in the world (Dynesius and Nilsson 1994). Altering the flow of rivers has significant effects on biodiversity changing the types of plants that can grow in them and subsequently the types of life that can inhabit them (Silvertown 2010). The alteration of hydrology is considered to be one of the three major causes of damage to aquatic life. The list of negative impacts from the creation of dams includes damage to migratory fish species, release of greenhouse gases (CH4, CO2), mercury contamination, and destruction by flooding. An almost universal effect of dams is the reduction in wetland area in the remaining floodplain along with the conversion of wet meadows to swamps (Keddy 2010). Damming and diverting have greatly impacted the conditions for aquatic and riparian organisms in standing along with flowing waters (Dynesius and Nilsson 1994).

There are three major ways that dams affect the ecosystem, (1) the ability of each river to serve as a corridor is reduced, (2) the habitats for organisms adapted to the normal water-levels and discharge regimens are impoverished, (3) and the function of the riparian one as a filter between upland and aquatic systems is altered greatly (Keddy 2010).

Fluctuations in water level are imperative for sustaining the abundance and diversity of wildlife species in wetlands. Species compositions and functions of wetlands are dictated greatly by the amplitude and frequency of flooding. This variation in the water levels occurs year to year. Wet meadows, swamps, marshes, and aquatic ecosystems represent a sequence of vegetation types associated with increasing the frequency of flooding (Dynesius and Nilsson 1994). High water periods drown woody vegetation and allow for wet meadow and marsh expansion. Low water periods are important for species that persevere as seeds buried in the sediment. In peatlands, water levels must be reasonably stable in order for peat to accumulate. Stabilization of water levels for uses for power generation, recreation, transportation or flood control results in lower species diversity and reduced wetland area.

Over the period of 1973-1987, Wolf Creek Nuclear Operating Corporation (WCNOC) surveyed biodiversity of the Neosho River from John Redmond Reservoir tailwaters below Wolf Creek. The results yield 52 fish species, with 13 species occurring in samples each year of the study. Changes in relative abundance were seen between years, however, were influenced by weather and appeared to influence fish populations in the Neosho River downstream of John Redmond Reservoir. Rainfall upstream in the basin determined the volume moving into John Redmond Reservoir, which then determined the volume of water released downstream into the Neosho River. The timing and amount of water released downstream effects the macroinvertebrate communities’ abundance and distribution. It also affects the reproductive rates of fish that spawn in the river, growth and survival of the adolescent fish, and prey/predator relationships (NRC 2006).

The USGS and USFWS researchers compared densities of numerous catfish species up and down stream of John Redmond Reservoir from 1991 to 1998 to determine if habitat, flow, and water quality alteration associated with the operation and creation of the flood control reservoir and dam had direct effects on downstream ictalurid populations, in particular the threatened Neosho madtom Noturus placidus (Wildhaber et al. 2000). The study found that Neosho madtom densities were significantly greater above John Redmond Reservoir than below John Redmond Dam. The determination that was made was higher upstream densities were associated with smaller sized gravel in the substrate and greater levels of turbidity. The up and down stream differences in substrate composition and turbidity were attributed to the operation of the dam and flood control reservoir. Water quality characteristics and physical habitat differ below John Redmond Dam and above John Redmond Reservoir. Higher minimum flows are the study’s recommendation to improve the densities of Neosho madtoms and other ictalurds (Wildhaber et al. 2000).

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Altered carbon cycle

Wetlands play a pivotal role in regulating exchanges of greenhouse gases from and to the atmosphere, including carbon dioxide (CO2), methane (CH4), nitrous oxide (N20), water vapor (H2O) and sulfur dioxide (SO2). Wetlands tend to be sinks for both nitrogen and carbon and sources for sulfur and methane compounds (Chawla 2008). All wetlands are capable of storing and sequestering carbon through photosynthesis and accumulation of organic matter in sediments, soils, and plant biomass. Wetland microbes mediate many of the essential biogeochemical processes that are needed in the environment. The carbon, phosphorus, sulfur, nitrogen and iron cycles all have some role in wetland communities and the bacteria present in the anoxic hydric soils are generally responsible for the various reductions and oxidations that occur (Faulwetter et al. 2008).

Many photoautotrophs are responsible for the initial fixing of CO2 into sugars that are utilized for energy. Besides primary production, decomposition is a function of microbial communities in wetland soils. Because of anaerobic conditions, the rate of decomposition is slow but the general soil organic matter is relatively high. Microbial communities in hypoxic conditions have the function of transforming the organic matter to usable forms of mineralized dissolved organic carbon (DOC) (Chawla 2008). This allows for plants, among other organisms, to utilize these substrates again for energy. Mineralization is a key component in this process, if mineralization did not occur, then carbon would stay in organic form and would not be able to be processed for plants.

Under conditions that are extremely reduced, where there is no satisfactory terminal electron acceptors available, microbes can utilize CO2. These methanogenic bacteria utilize the CO2 as a terminal electron acceptor, which results in the production of CH4. Methanotrophs utilize methane as their energy source and oxidize it to CO2. Of the two carbon green house gases, methane has a much larger rate of thermal effect, around 20 times stronger than CO2; however methane has a dramatically shorter lifespan in the atmosphere (Aber et al 2012). Methanotrophs in hydric soils will be active right above the anaerobic/aerobic separating line. Due to this placement, up to 90% of the CH4 in hydric soils can be consumed before it enters the atmosphere (Chawla 2008).

While understanding the complex processes that takes place in wetland environments, generally, wetland plants grow quicker than they decompose which contributes to a net annual carbon sink. Heavy saturation of wetland soils limits the oxygen diffusion into sediment profiles producing anaerobic conditions. These conditions slow the rate of decomposition, which leads to the storage, and build up of large amounts of organic carbon within the wetland sediments. Anaerobic conditions however, are conducive to the production of N2O and CH4. In periodically inundated systems, methane emissions can be greatly variable. When the wetlands are inundated, and anaerobic conditions are met, CH4 can be produced. When these wetlands are dry, they may act as sinks for CH4 (Keller 2011).

Wetlands are also complexly involved in horizontal transport of carbon between different ecosystems (Mitra et al. 2003). Wetlands are inclined to trap carbon-rich sediments from watershed sources but also release dissolved carbon through water flow into adjoining ecosystems. These horizontal transport pathways could potential affect both emission rates and sequestration of carbon.

Wetlands are able to contain carbon-rich sediments from catchments but potentially can disperse carbon through water flow into floodplains. Carbon can accumulate on floodplains and is redistributed by natural flood events and then concentrated to adjoining river channels, floodplains, and wetlands as floodwaters recede. This promotes the biomass growth and productivity in these areas.

The hydrological connections between waterways and their associated floodplains are important for the exchange of nutrients and carbon. The connections are essential for the functioning and integrity of floodplain river systems. Drainage and oxidation of wetland soils can decrease CH4 and production and lead to huge net losses of sediment organic carbon. Decreases in CH4 production can occur from drained wetland sediments; therefore, drained channels can be net emitters of CH4 (Mitra et al. 2003). This means that wetlands may either be sources of carbon or sinks for carbon depending on their type and can switch between becoming net sources and being carbon sinks. This switching can be a natural process due to seasonal variations or other factors or human management, such as the controlling of waterways via dams, can affect it. Stabilization of water levels for uses, such as flood control, has the potential to reduce wetland area and lower species diversity. By utilizing dams to reduce spring floods dams eliminate immense areas of wetlands in a watershed. Almost every watershed in the world has been altered by the construction of dams (Keddy 2010). If the wetland starts to dissipate due to the reduction of stream flow then the aforementioned carbon process is diminished causing an unnatural alteration to wetlands as natural carbon sinks.

John Redmond Dam, however, does not have significant evidence that there has been a direct effect from the dam to the dissipation of wetland environments leading to a significant change in carbon storage or sequestration. This could be due to various reasons, namely the age at which the dam was constructed and the attention attributed to the measure of carbon storage in the particular area before and after the dam was operational.

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Alteration of plant life

Upstream Impacts:

Inundation of habitats

The most general upstream effect of dams on plant life is the inundation of the habitats (Nilsson and Berggren 2000). Upstream from the dam, the free-flowing stream habitat transforms to a steady-water reservoir ecosystem. Changes to the upstream ecosystem include change in temperature, chemical composition, dissolved oxygen levels and physical characteristics (International Rivers 2016), The impoundment of water from dams changes the flow regime of some floodplains from intermittent inundation to permanent (New South Wales 2013). Both wetland and terrestrial plants must adapt to their shift in environment. When completely inundated, some species will immediately cease growth and die. Others will respond with structural and biochemical adaptations that restores the plant’s growth ability. Structural adaptations may include the development of enlarged air spaces in their leaves, stems, roots, or bark. A structural adaptation includes the development of aerenchyma, porous tissue that have large air-filled spaces that allow for rapid gas diffusion. Common wetland plants that have aerenchyma include cattail (Typha), green ash (Fraxinus pennsylvanica), northern white-cedar (Thuja occidentalis), and water hemlock (Cicuta maculate). Lenticels, another structural adaptation, are enlarged pores on bark that allow for oxygen diffusion to submerged roots. Green ash and red mangrove (Rhizophora mangle) are common wetland trees that have lenticels. Biochemical adaptations may be a plant’s ability to switch to respiration without oxygen. The anaerobic respiration converts food into energy but has toxic byproducts that plants may excrete, immobilize, or convert (Aber et al. 2012). The loss of plant life with inundation may cause environmental problems with the release of carbon dioxide and methane during decomposition. Flooded soils and vegetation may also release methylmercury, that accumulates in predatory fish, and nutrients, such as nitrogen and phosphorous that increase aquatic productivity (Nilsson and Berggren 2000).

Creation of new habitat

New shorelines are created with the creation of the reservoir upstream of the dam. Evolution of new wetland habitats are dependent on the duration, timing, and frequency of water levels. Generally, the new shoreline of a reservoir begins with low biodiversity and species density. Even after a recovery phase, the species density may never reach the pre-dam values. Nilsson et al. found that species density declined in older dam reservoir systems to levels similar to young reservoirs. The erosion of the fine-grained substrate and the constraint on dispersal attributed to the reduction of available species and ultimately, the decline in species density in older reservoirs. Based on the management of the reservoir, there may be large fluctuations in water levels that cause interruptions in the development of new habitat. Low water level fluctuations were found to have more persistent shoreline vegetation similar to lakes (Nilsson and Berggren 2000). Overall there is a reduction of habitat due to factors includes frequency and duration of flooding of terminal wetlands and floodplains and the change in area of these ecosystems (New South Wales 2013).

Downstream Impacts: Hydrology, Geomorphology, and Riparian Communities

The formation of a reservoir commonly impacts the frequency of downstream flooding and sediment cycling. The downstream flooding frequency is typically reduced and may be displaced in time. Reducing the flooding frequency of a river changes the species composition of the riparian areas. This change in hydrology starts a new evolution of riparian communities. The species that were unable to tolerate the characteristic properties of riparian areas surrounding a free-flowing river channel may now survive the drier and more stable environment. The frequently flooded areas may change from wetland species to an upland riparian forest over time. A more permanently flooded habitat may also permit the establishment and dispersal of exotic species that become invasive to the environment (New South Wales 2013). But as the connectivity of the river channel to its downstream component is reduced, the surrounding plant life populations become disjointed and disturbed and may lead to extinction of riparian species. (See Figure 1. Taken from Nilsson and Berggren 2000) Geomorphologic processes such as sediment cycling are altered with the construction of a dam. Dams may impound large masses of sediment that had previously traveled downstream. Impoundment may cause slow build-up of deltas and coastline erosion as seen in the coastal marshes of the Mississippi River in Louisiana. Erosion downstream from a dam may lead to channel simplification and reduced morphological activity in the downstream channel (Nilsson and Berggren 2000). With the changes to the hydrology and geomorphology, the riparian communities are affected by both the changes to the flooding frequency and erosion deposition cycles.

Nilsson Figure on Succession of Plant Species

Overview of riparian succession following a reduced flooding frequency downstream from dams. (Recreated by author from Nilsson and Berggren 2000)

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Dam Operation and Maintenance

Another factor to consider is the cost of maintaining the reservoir. Maintenance on Dam equipment and man hours to pay employees to maintain equipment can take a large financial toll on the owner of the dam and can also have a direct link to the local economy. In the case of John Redmond Reservoir, its intent was not primarily to be recreational, instead it was intended to allow for a steady supply of water and mitigate flooding in the region. Recently the US Army Corps of Engineers approved a request from Kansas to increase the water storage capacity of John Redmond by about two feet. (John Redmond Reservoir Reallocation Approved, n.d.) This will be done via a dredging process that is currently underway. As with any piece of equipment that humans have engineered and frequently use, routine maintenance is required for safe operation. Over time, changes in technology and procedure or simple neglect have left many dams in disrepair. Often times, the original purpose the dam was created is no longer valid or needed. This results in an excess of dams that are unjustified in their existence. According to the US Army Corps of Engineers there are at least 80,000 dams greater than 6 feet along the waterways of the United States – and at least tens of thousands of smaller dams pepper our rivers and streams. Secretary of the Interior Bruce Babbitt has pointed out that, “on average, we have constructed one dam every day since the signing of the Declaration of Independence.” (Rivers, Dam Effects on Rivers)

From an industrial standpoint John Redmond Reservoir has significance to the Wolf Creek Nuclear Power Plant (Wolf Creek Nuclear Operation Corporation- WCNOC). WCNOC is Kansas' first and only nuclear power generating station, for three utility owners (Westar Energy, Great Plains Energy and KCP&L, Kansas Electric Power Cooperative, Inc.) in Kansas and Missouri. The plant provides energy to the citizens of Kansas and Missouri and has been since 1985. The plant generates about 1,200 megawatts of electricity, which is enough energy to power more than 800,000 homes in the aforementioned states. JRR serves as the backup cooling Reservoir to the Coffee County Lake (also another manmade lake) which is the primary cooling method for the Wolf Creek reactor. The water at John Redmond can be manually pumped from the primary Reservoir to Coffee County Lake through a series of piping to supplement water in storage for cooling at Coffey County Lake. It is important to note that the lake water in either of the reservoirs does not directly come in contact with any radiological aspect of the power plant both the cooling system for the reactor in the cooling system that controls condensation of steam are two separate systems. Water that is located in the reactor portion of the cooling system has been in the pipe work since the initial creation the power plant.

Hydro power is another popular power option. The Federal Energy Regulatory Commission (FERC) regulates over 2,300 hydroelectric dams. In addition, there are over 240 federal dams that produce hydroelectric power. As of 2013, there were over 1,672 hydroelectric producing plants in operation in the U.S. With Hydroelectric power, energy is created from flowing water spinning turbines. The mechanical apparatus is typically housed inside of a dam with a water source (reservoir) supplied from rivers or from man-made basins. Such is the case of JRR. Water flows from a higher level to a lower level through a tunnel towards a turbine to create power. Hydropower represents about 16% (International Energy Agency) of total electricity production. Unfortunately, the small stature of the JRR dam site makes the option less feasible than larger dams such as The Grand Coulee dam on the Columbia River in Washington State with a capacity of more than 6,750 megawatts (MW).The overall cost of maintaining power producing equipment at JRR would be prohibitive when considering financial gains and losses.

Removal of the dam structure

When it is determined that a dam no longer serves a purpose or would more difficult to repair, removal of the structure is an option. Though this can still be a costly feat. It is important to note that, in the majority of cases where dams have been removed, money is actually saved over long periods. The Association of State Dam Safety Officials (ASDSO) estimates the cost of removing dams or otherwise restoring waterways to close to natural conditions (removal of dam only) in the United States in excess of $50 billion. (IV, 2009) Expenses associated with maintenance and safety repairs, combined with expenses associated with fish and wildlife protection, can be substantially mitigated or all together removed. Economic benefits in the form of recreational revenue increase in opportunity as well. Activities such as kayaking, camping and fishing can be introduce with the return of natural environmental features and aesthetic value.

Factors such as the dams size, location, materials used during construction, and considerations of what is lost or gained with the dam’s demise are all considered. Perhaps most importantly is the environmental implications of the removal. Silt and debris trapped above dam accumulates heavy metals and pollutants over time. Removal of a dam without proper preemptive cleanup of such pollutants can kill fish and plants downstream, further damaging the environment.

Removal methods

The structure will typically be removed in one of two ways. The method that allows for a gradual restoration of the environment over a period of time (often years) is the paced dismantling of the structure. Sections of the structure are removed portions at a time to allow for nature of regulate the reintroduction of equilibrium to the area. An alternate method is to divert the water way to allow for a “dry” takedown. For obvious reasons, the later method introduces more factors to the equation as the range of affected human and environmental aspects increases. (Rivers, n.d.) To date, 62 dams have been removed to restore rivers in the U.S. during 2015. States include California, Connecticut, Maine, Michigan, Minnesota, Montana, North Carolina, New Hampshire, New Jersey, New York, Ohio, Oregon, Pennsylvania, Tennessee, Virginia, and Vermont. Additionally, from 1912 to 2015, 1300 dams have been removed collectively. (Rivers, 62 Dams Removed to Restore Rivers in 2015)

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Comparison to Melvern Lake

Melvern Lake Aerial Image USACE

Aerial image of Melvern outlet pool with dam in right background.
Taken from USACE. (USACE, n.d.)

In comparison, Melvern Lake has a similar construction to John Redmond. Melvern is also an earthfill embankment but only extends 9,700 feet and rises 125 feet above the river valley. Construction began in 1967 and was completed in 1972. Melvern Lake water level is maintained by a series of hydraulic gates located at the bottom of the control tower. Water flows through a conduit for approximately 754 feet before entering the Marais Des Cygnes River. Like John Redmond, Melvern Lake is used for flood control, water supply, and recreation. Melvern Lake is also used for fish and wildlife conservation. As part of natural resource management, the Corps of Engineers and the Kansas Department of Wildlife, Parks, and Tourism work together at Melvern Lake to create and manage the natural resources, including wetlands (USACE, n.d.).

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