Healthy Freshwater Systems Benefit Fish, Wildlife and People

Such declines affect more than just fish and other wildlife. Migratory fish support commercial and recreational fishing industries that generate tens of billions in revenue each year. In Alaska’s Bristol Bay alone, the sustainable commercial harvest of wild salmon is valued at $2.2 billion annually and employs more than 10,000 people. In 2022, Bristol Bay experienced a record return of nearly 72 million sockeye salmon. This yearly migration makes for a rich ecosystem and remarkable way of life for people in Indigenous communities where the harvest of wild salmon is a cherished part of their culture.

Our Strategies for Healthy Freshwater Systems and Improved Fish Migration 

1. Protecting Freshwater Systems

The Nature Conservancy (TNC) impacts conservation in nearly 80 countries, has restored more than 4,900 miles (some 8,000 kilometers) of rivers, and has protected more than 125 million acres (51 million hectares) of land. For fresh water, this is important because healthy waters flow through healthy lands.

But we’re not even close to finished. As part of our 2030 goals, TNC aims to conserve 1 million kilometers (621,000 miles) of river systems and 30 million hectares (74 million acres) of lakes and wetlands by engaging in collaborative partnerships, promoting innovative solutions, and supporting policies that improve the quality and amount of water available in freshwater ecosystems.

2. Removing Barriers for Healthy Rivers and Fisheries

Only some one-third of the world’s largest rivers remain free flowing. Most have been severed by dams or other barriers. For example, in the United States, only some 2% of the nation’s 3 million miles of rivers and streams remain free-flowing and undeveloped, similar to other heavily developed nations. And countless other, smaller rivers and streams been altered by dams, locks, levees or culverts that impair or prevent the migration of aquatic species. 

Such work continues, not only on Maine's Kennebec and Penobscot rivers, but on rivers around the globe. Below is a snapshot of how TNC addresses barriers that affect our freshwater systems:

Removing Obsolete Dams. In cases where the value dams provide is outweighed by operational costs and the impacts to nature and people, TNC supports their removal.  The removal of dams restores the natural flows and conditions of rivers as well as the benefits they provide. Obsolete dams can have a wide range of impacts on the environment and local communities, including loss of biodiversity, blocking fish migrations, trapping sediment and nutrients that maintain habitat and estuary health, and altering flow patterns that drive the productivity of downstream floodplains and wetlands. These impacts can affect public safety, food and water supplies, livelihoods, recreation and overall community well-being.

Avoiding New Dams—or ensuring the “right fit.” More than 161,000 miles (260,000 kilometers) of free-flowing rivers are at risk of being impacted by the construction of new hydropower dams—equal to more than 39 times the length of the Nile. The impacts of these new dams would fall disproportionately in river basins with the greatest freshwater fish harvests and with the highest diversity of freshwater species, and—in many cases—greatly affect critical food sources for or displace Indigenous peoples.

Although dams can provide hydroelectric power, help reduce flood risk and provide sources of water, their high ecological and socioeconomic costs mean they must prove their worth, and the case against them in our evolving energy sector is considerable. When and where new dams are proposed, we advocate for large-scale planning that factors in energy demand, other sources of renewable energy, project costs, and environmental and societal impacts. Our work within Brazil’s Tapajos River basin well illustrates this strategy put into action. 

A Focus on Culverts. When roads cross streams—often over culverts—it can be problematic for the stream’s health and the safety of the road. Not only can poorly designed or undersized culverts hinder or block the migration of aquatic species, they can fail due to the increasing intensity of storms and growing development, which produces more runoff. TNC works with many partners to identify and fix problematic road crossings to enhance the movement of aquatic species as well as help road managers avoid tragedies, decrease much costlier emergency repairs and reduce expensive detours for travelers.

3. Restoring Streams, Rivers, Wetlands and Floodplains

Sometimes protecting freshwater systems or removing barriers isn’t enough. TNC’s work to restore streams, rivers, wetlands and floodplains is a strategy we use to mitigate the impacts of manmade structures or development that affect the hydrology and health of freshwater systems and the wildlife and people that depend on them.

Many of these manmade structures, like ditches, levees or dikes, are designed to drain wetlands or straighten rivers by cutting them off from side channels or floodplains, which often provide some of the most important habitat for fish and a wide array of other species. These same structures can drastically impact the trees and plants in these places, which are adapted to periodic, natural fluctuations of high and low flows. 

Examples of Our Freshwater Work

The projects below are not a complete listing of the projects TNC is involved with to help improve the health of our freshwater systems. Rather, what’s listed below serve as some of our best examples, many of which feature videos. 

Dam Removals or Planning and Culvert Improvements:

• Helping shape Brazil’s hydropower future
• TNC is helping remove obsolete dams and plan for new ones in Europe.  
• The largest dam removal project in Connecticut
• Dam removals are helping ‘free’ Kentucky’s Green River
• Two dam removals and a fish passage made a big difference at Maine’s Penobscot River
• Dam removals in Massachusetts brought back to life a ‘once-dead’ river
• Removing old dams created new hope for New Hampshire’s Bellamy River
• Removing a dam helped improve the health of the Delaware River
• TNC has prioritized dam removals throughout Tennessee
• Removing ‘deadbeat’ dams is reconnecting and restoring Vermont’s ‘broken streams’
• TNC scientists recently detailed efforts to streamline culvert improvements in Maine
• TNC received NOAA grants to improve culverts and bridges in North Carolina to improve fish passage and river health
• TNC helped the State of Georgia produce a handbook to help improve the design of roads that cross streams
• Tidal gates can also be a barrier for migrating fish; learn how TNC in Oregon addresses these to benefit salmon
•  This article published in TNC’s magazine provides an overview of work to address barriers to fish migration and the other impacts they have on people and nature

Freshwater Restoration:

• The restoration of 3,000 floodplain acres along 14 miles of the once-“channelized” Pocomoke River in Maryland
• Nearly 150 projects in Oregon benefit salmon
• Several projects in Ohio, funded through the state’s mitigation program, are improving river health
• Projects in Arkansas benefit the Cache River
• The reconnection of a 3.5-mile-long side channel along the lower Mississippi River
• Restoring meanders to Montana’s Ruby River
• Big lessons learned from the restoration of Little Creek in Missouri
• Protecting and restoring Chinook and steelhead habitat in the upper Snake River in Idaho
• Restoring spawning habitat in the Great Lakes
• Restoring wetlands on Hawaii’s island of O’ahu

Restoring and Reconnecting Wetlands and Floodplains:

• A 25-square-mile floodplain reconnection at “Mollicy Farms” along the Ouachita River in Louisiana
• A 6,700-acre project at TNC’s Emiquon Preserve along the Illinois River in Illinois
• A series of habitat reconnection projects on the Willamette River in Oregon
• A 1,040-acre levee “setback” project along the Missouri River in Missouri
• Work in Washington’s Puget Sound benefits salmon
• Giving more room to the Sacramento River in California
• Restoring tidal wetlands benefits salmon in Oregon

Protecting and Restoring Stream Flows:

• TNC is behind a myriad of efforts to protect groundwater that not only supplies much of the flows in our rivers and streams, but also provides cooler waters critical for the survival of many aquatic species, including Florida’s endangered manatees. 
• The Sustainable Rivers Program is a partnership between TNC and the U.S. Army Corps of Engineers—the largest water manager in the U.S.—to improve the way some Corps dams are operated to produce more benefits and minimize environmental impacts.
• We work with farmers to reduce the amount of water they use to irrigate their crops, which leaves more for nature. Our work in Nebraska, Arizona, Arkansas and several other states and countries serve as prime examples of this strategy put into practice.
• TNC and its partners manage 32 Water Funds initiatives in various stages of development around the globe that provide a steady source of funding for the conservation of more than 7 million acres of watersheds and secure drinking water for nearly 50 million people. Many of these water funds also help ensure adequate and/or cooler flows and improved water quality, both of which benefit fish and other species. Colorado’s Yampa River Fund employs a variety of strategies aimed at protecting flows, and water funds we’ve helped launch in Africa and India that focus on agriculture improvements do as well. In Ecuador, two water funds are aimed at protecting water—and flows—at headwater sources.
• We’re also working to address water flows and water scarcity in a variety of different ways throughout the drought-prone Colorado River Basin in the U.S.

Partnerships and Funding that Improve Freshwater Systems

As an environmental non-profit organization, the support of our donors enables TNC to leverage its science-based expertise and past work to influence and implement new projects that improve the health of freshwater systems around the globe. It’s important to note, however, that in the face of so much loss and degradation of habitat, partnerships—and the funding they can provide—are paramount in order to work at scale and achieve meaningful results.

In the U.S., critical partnerships and related funding include, but are not limited to:

• The National Oceanic and Atmospheric Administration (NOAA)
• The National Fish Passage Program
• The U.S. Fish and Wildlife Service
• The U.S. Forest Service
• The Natural Resources Conservation Service
• The Bureau of Indian Affairs
• Native American Fish and Wildlife Society
• The Federal Highways Administration
• The National Fish Habitat Partnership
• American Rivers
• The Atlantic Salmon Federation
• Trout Unlimited
• Numerous state fish and wildlife agencies

Internationally, critical partnerships include, but are not limited to:

• Dam Removal Europe
• World Wildlife Fund
• World Fish Migration Foundation
• Wetlands International
• Fauna and Flora International
• Conservation International