The Story of Lake Restoration

Agricultural practices

Farms often over-apply high amounts of nutrient-rich fertilizer to their fields, which can runoff into nearby lakes.

Eutrophication

Excess nutrient pollution, or eutrophication, often occurs in lakes with highly agricultural watersheds. This high nutrient availability can lead to rapid algal growth events, also called algal blooms. These algae may be toxic to humans and animals and can lead to other problems for lakes, like oxygen depletion.

Sewage Contamination

Without proper wastewater treatment, sewage pollution into lakes can also lead to eutrophic conditions and algal blooms, and pose a public health risk to people who use the lake.

Mercury Contamination

Mercury contamination -  Mercury can find its way into lakes  by both natural sources, like geologic deposits, and human sources, including coal combustion and mining. Once in aquatic ecosystems, mercury bioaccumulates in fish, negatively impacting the entire food chain.

Case Study 1B: Lake Erie

Eutrophication of surface water is a global concern. Of the five Great Lakes, Lake Erie has been most seriously affected by eutrophication (Makarewicz & Bertram, 1991). Lake Erie has a history of environmental degradation, with past agricultural and wastewater runoff leading to eutrophication throughout the lake (Makarewicz & Bertram, 1991). During the 1960s and 1970s, increased phosphorus inputs degraded water quality and reduced lake oxygen levels (Scavia et al., 2014). In response, phosphorus abatement programs were implemented in 1972 as part of the  Great Lakes Water Quality Agreement (GLWQA)  (Scavia et al., 2014). This was a relatively quick response, with evident decreases in total phosphorus (Scavia et al., 2014). Since the mid-1990s, however, Lake Erie is returning to a more eutrophic state (Scavia et al., 2014). This is indicated by increases in cyanobacteria and the resurgence of benthic algae growth as well as hypoxia (Scavia et al., 2014).

Case Study 1C: Lake Erie

To reduce Lake Erie’s eutrophication, there is ongoing restoration of the Great Black Swamp in Ohio. The Great Black Swamp once spanned 1,500 square miles from Fort Wayne, Indiana to Sandusky, Ohio (Eklov, 2019). Settlers in the late 19th century drained the wetland and converted it to be an area highly productive in agriculture (Eklov, 2019). Sediment and nutrients from the farm fields washed into the Maumee River, and ultimately into Lake Erie (Eklov, 2019). Today, the Great Black Swamp is one of the major sources of agricultural phosphorus seeping into the western portion of Lake Erie through the Maumee River (Eklov, 2019). Wetland scientists believe that restoring parts of the Great Black Swamp could help save Lake Erie from future eutrophication and algal blooms (Eklov, 2019). 

Case Study 1D: Lake Erie

Through ongoing restoration efforts, the Black Swamp Conservancy, a land trust and non-profit land conservation organization serving northwest Ohio, is re-creating a functioning floodplain complex to help create a cleaner Lake Erie (Eklov, 2019). This is being done to also expand habitat and support larger and healthier wildlife populations located in and around Lake Erie (Eklov, 2019). One restoration method involved restoring the natural hydrology of the swamp by removing drainage tile and restoring the swamp to create vernal pools and wetlands (Eklov, 2019). In addition, the Black Swamp Conservancy is transforming farm fields into aquatic wetland and upland habitat to trap as many nutrients as possible (Eklov, 2019). These restoration efforts occurred from 2017 to 2019 (Black Swamp Conservancy Habitat Restoration, n.d.). In a study on the restoration of the Great Black Swamp and its impact on Lake Erie, scientists believe that restoring and creating 20,000 - 40,000 hectares or 5-10% of the original wetlands in the Black Swamp to optimize nutrient reduction can reduce phosphorus loading by 480-960 metric tons per year or 18-37% of the annual phosphorus loading by the Maumee River to Lake Erie (Mitsch, 2017).

Case Study 2A: Lake Søllerød

 Lake Søllerød  is a post-glacial lake located about 12 miles north of Copenhagen, Denmark. It is about 13 hectares in area with a maximum depth of 9.8 meters and average depth of 5.6 meters. The lake is surrounded by parks, forests, meadows, organic cropland, and residential land.

Case Study 2B: Lake Søllerød

The lake has a  history with wastewater pollution and very high phosphorus levels . While the phosphorus levels have decreased significantly over time with developments like wastewater treatment, the lake still suffers from algal blooms due to elevated phosphorus levels. Much of this phosphorus is stored in lake sediment and can mobilize if the sediment is disturbed. Apart from high nutrient concentrations,  organic matter at the bottom of the lake cannot break down  due to the anoxic conditions of the hypolimnion, which makes the water murky and smelly.

Case Study 2C: Lake Søllerød

Starting in July, 2019,  a pilot project from the Technical University of Denmark  tested an experimental method of reducing phosphorus concentrations in the lake by increasing the redox potential of lake sediments. Redox (or oxidation-reduction) reactions, like decomposition, require oxygen or another oxidant to accept electrons.

For this to happen in an environment devoid of oxygen, the researchers use sediment microbial fuel cells (SMFCs): structures containing a special type of bacteria that can transfer electrons extracellularly.

Case Study 2D: Lake Søllerød

The in-lake experiment involved two SMFCs, one resting on the bottom of the lake and one suspended in the water column. The bacteria transferred electrons from the lake sediment to an electrode (a conductor that’s part of an electrical circuit). The electrons then traveled up the circuit to the second SMFC. Because the suspended fuel cell was higher in the water column, oxygen was available for the electrons to reduce, completing the redox reaction. Rather than oxygenating or aerating the lake, the study sought to facilitate redox reactions in the absence of oxygen in the hypolimnion.

Case Study 3A: Loktok Lake

Loktak Lake is a freshwater lake located in Manipur, India. It is the largest freshwater lake located in South Asia, spanning an area of 26, 600 hectares (Loktak Lake | Ramsar Sites Information Service, 1990) with an average depth of 2.7 m  (Wetland Complex, n.d.). Loktak Lake is known for its Phumdis, which are naturally occurring mats of floating biomass. Phumdis can also be shaped by humans. Loktak Lake is more than just a beautiful sight. It is a lifeline for local communities who depend upon fishing for their sustenance and livelihoods. It is important to note that Loktak Lake is a Ramsar Site, which is usually for wetlands, but Loktak Lake is considered to be between a lake and a wetland (Loktak Lake | Ramsar Sites Information Service, 1990). 

Case Study 3B: Loktok Lake

Loktak Lake has been greatdegraded mainly due to anthropogenic activity, including urban development, agriculture, and climate change (Kangabam et al., 2015). The waste products from urban sewage have flowed into the lake through different rivers (Kangabam et al., 2015). Urban sewage has deteriorated the lake and affected the ecosystem (Kangabam et al., 2015). Agriculture and the use of synthetic fertilizers and pesticides have also been a strong source of pollution for the lake (Kangabam et al., 2015). The long-term impacts of this immense degradation include a loss of flora and fauna, including fish, and the quality of the lake decreasing due to urban and agricultural waste (Kangabam et al., 2015). 

Case Study 3C: Loktok Lake

The Champu Khangpok Floating Village is located amid Loktak Lake and consists of 140 families who depend upon the lake for their sustenance and livelihoods (4).  Their lives are at risk with a declining fish population. The women fishers are at the center of a grassroots activism project that is working to restore the lake and protect the fish that are key to their sustenance and livelihoods (4). The women fishers have developed a two-pronged strategy for self-determination by creating two self-help groups (4). One group works to sustain their lives through a micro-financing venture in which funds are pooled (4). This group also involves thinking of ways to supplement their income (4). The other group works to garner strength through an established network amongst themselves and other fishers for lake conservation (4). It is important to note that while these self-help groups are ongoing to restore the lake, the Champu Khangpok village has not stopped fishing. 

Case Study 4A: Lake Champlain

Lake Champlain is a freshwater lake in Vermont, U.S. and a small portion of Quebec, CAN. While not insignificant in size, its surface water covers 435 square miles, it is notably thin for its size, reaching only 12 miles at its widest point (Lake Champlain Land Trust, 2022). The lake has an average depth of 64 feet with a maximum depth of 400 feet. (Lake Champlain Land Trust, 2022). Lake Champlain provides various ecosystem services for the surrounding community, such as recreation, historical relevance (the lake is home to one of the oldest fossil reefs in the world!) and is the primary drinking water source for approximately 200,000 individuals (Lake Champlain Land Trust, 2022).

Case Study 4B: Lake Champlain

Lake Champlain is highly impacted by the introduction of Aquatic Invasive Species (AIS) with 51 known and monitored invasive species actively under management by organizations such as the Lake Champlain Basin Program. Of those 51 managed AIS, 7 are recognized as being high priority for removal, Alewife, Asian Clam, Eurasian Watermilfoil, Japanese Knotweed, Purple Loosestrife, Water Chestnut, and Zebra Mussel (Lake Champlain Basin Program, 2005). 

In 2005 the  Champlain Basin Aquatic Nuisance Species Management Plan  was developed to manage and control AIS in Lake Champlain. Hundreds of thousands of dollars were already being spent on management each year but lack of coordination between social, political, and economic structures on the issue allowed the problem to grow and spread. The goal of this plan was to coordinate with stakeholders across the watershed in order to increase the efficiency and effectiveness of efforts (Lake Champlain Basin Program, 2005).

Case Study 4C: Lake Champlain

In the first two years the plan identified the following actions to take to address the AIS problem: 1. Develop and maintain an ANS Advisory Committee to guide Plan implementation and set priorities on a regular basis; 2. Continue to strengthen the newly-established Adirondack Park Invasive Plant Program; and 3. Determine the population status of alewives in Lake Champlain (Lake Champlain Basin Program, 2005). 

Case Study 4D: Lake Champlain

However, aside from the last priority, the plan failed to establish actionable goals and was never updated. The AIS issue is still very much present in Lake Champlain and stakeholders operate in a patchwork. From the perspective of the planners, this patchwork of actions was not a strong enough response to the issue at hand. But they failed to engage with the Champlain community in an effective way to produce the change they deemed necessary. Restoration ecologists and practitioners can learn a lot from initiatives like this which can create robust, scientifically backed plans and, in some ways, fail to put those plans into action due to their inability or unwillingness to meaningfully engage with stakeholders by meeting them where they are rather than exerting top-down directives. 

Case Study 5A: Lake Mead

At full capacity, Lake Mead is the largest reservoir in the United States by volume holding a maximum of 28.23 million acre-feet of water. It was formed following the construction of the Hoover Dam on the Colorado River, flooding 247 square miles of the Mojave Desert in the process. The dam was built to provide flood control, navigation, and generation of electrical energy. Water storage in Lake Mead has allowed for the development of the region supplying municipal water for 25 million people in the cities of Las Vegas, Henderson, North Las Vegas, and Boulder City, NV. Additionally, Lake Mead provides irrigation to agriculture in the Colorado Basin, Imperial Valley, and municipal growth in Los Angeles (Billington et al. 2005). 

Case Study 5B: Lake Mead

However, the lake's water levels have seen a significant decline in recent years, primarily attributed to unsustainable water usage and the impacts of climate change, resulting in both human-induced and climate-induced droughts. In July 2022, the water level of Lake Mead reached a low point of 1041.30 feet, representing just 27% of its total capacity (NASA Earth Observatory, 2023). This decline is not an isolated event but rather part of a steady decrease observed since 1999 which poses significant challenges for ensuring water supply reliability, sustaining hydroelectric power generation, and preserving ecosystem health. It underscores the critical importance of implementing sustainable water management practices and developing adaptation strategies to address the evolving environmental conditions. In response, researchers have begun exploring the long-term viability of Lake Mead and the Hoover Dam, as well as the exploration of alternative water management solutions (Barnett, 2008; Wright & Kennedy, 2011; Yao et al., 2015).

Case Study 5C: Lake Mead

In recent years, stakeholders ranging from governmental bodies to non-governmental organizations have turned their attention to the water held within Lake Powell, 600 miles upstream, considering it as potential solutions to a host of downstream challenges. This focus has given rise to the High-Flow Experiments.

Case Study 5D: Lake Mead

Conducted from the Glen Canyon Dam, the High-Flow Experiments involve the controlled release of a substantial volume of water over a condensed time frame, aiming to replicate natural flood events. These experiments serve dual purposes: first, they align with initiatives such as Fill Mead First, advocating for the prioritization of Lake Mead's water levels over those of Lake Powell. Second, they seek to revive ecological processes disrupted by the dam's operations, with particular emphasis on the Grand Canyon region (Bureau of Reclamation, 2016).

Case Study 5E: Lake Mead

By emulating natural flood patterns, the High-Flow Experiments provide valuable insights into sediment transport, erosion dynamics, habitat restoration, and the behavioral patterns of native fish species (Wright & Kennedy, 2011). This data informs comprehensive strategies aimed at balancing human water needs with the imperative of ecosystem preservation, thereby addressing the intricate water management challenges prevalent in the region.

Case Study 5F: Lake Mead

Lake Mead stands as a testament to human engineering rather than a product of natural processes. Its formation was orchestrated through the monumental endeavor of constructing the Hoover Dam, requiring significant expenditure of energy and material resources. However, the maintenance of this reservoir and dam demands ongoing investments of resources, a demand that escalates over time due to the compounding effects of interference with natural systems.

Case Study 5G: Lake Mead

Dr. Ryan Emanuel emphasizes the complexity of ecological restoration efforts in the context of human-made lakes like Lake Mead, stating that "The formulaic nature of restoration presents challenges, as ecosystem functions can’t simply be extracted from one place and expected to serve the same role elsewhere” (personal communication, 2024). This perspective sheds light on the challenges of restoring ecosystems surrounding human-made lakes like Lake Mead, emphasizing the need for holistic approaches that address underlying issues such as excessive water and energy consumption. Until these root causes are addressed, restoration efforts for Lake Mead will likely be only partially effective, considering its primary functions as an engineered system for power generation and flood mitigation. As Dr. Emanuel put it, "While new ecosystems may emerge, fundamentally, these are engineered systems serving other purposes like drinking water or irrigation" (personal communication, 2024).