River conservation statistics show a mixed national picture. The EPA’s National Rivers and Streams Assessment found substantial problems in biological condition and nutrient pollution, while habitat measures and restoration programs show areas of progress. American Rivers also reports a growing record of dam removals that has reconnected thousands of river miles.
Contents
- National biological condition
- Nutrients, bacteria, and contaminants
- Physical habitat and riparian areas
- Regional differences
- Restoration through the National Estuary Program
- Dam removal and river reconnection
National biological condition
The EPA National Rivers and Streams Assessment Report describes conditions across the conterminous U.S. rivers and streams included in the survey definition. Its biological indicators reveal a wide gap between physical habitat and the organisms living in the water.
For benthic macroinvertebrates, only 28% of river and stream miles were in good condition. Another 25% were fair, and 47% were poor. In other words, less than one-third of assessed river and stream miles had healthy communities of bottom-dwelling organisms, while close to half were rated poor by this indicator.
The fish community indicator was more favorable but still left substantial room for improvement: 35% of river and stream miles were good, 19% were fair, and 29% were poor. A further 16% were not assessed for fish in the EPA assessment. The good-condition share rose from 25% to 35% between the surveys reported by the EPA, while the poor-condition share in the national fish indicator was 29%.
The EPA also estimated that biological condition could improve on about 20% of river and stream miles if nutrient condition improved from poor to fair or good. Its national relative-risk estimates for poor benthic macroinvertebrate condition were 2.1 for acidification, 1.7 for phosphorus, and 1.5 for nitrogen. These are risk estimates, not a direct count of damaged miles.
Nutrients, bacteria, and contaminants
Nutrient condition is one of the clearest conservation challenges in the EPA report. Nationally, 32% of river and stream miles were in good condition for total nitrogen and 44% were in poor condition. For total phosphorus, 36% were good and 42% were poor. The report also separately summarizes 42% of miles as poor for phosphorus and 44% as poor for nitrogen.
The national trend was not uniformly negative. Good-condition phosphorus miles increased by 16 percentage points between 2013–14 and 2018–19, while poor-condition phosphorus miles decreased by 18 percentage points. In the Temperate Plains ecoregion, however, good-condition nitrogen miles declined by 11 percentage points over the same survey period.
Recreational and chemical measurements add further context:
| Indicator | National result | Measurement context |
|---|---|---|
| River and stream miles exceeding the enterococci benchmark | 20% | EPA recreational benchmark |
| River and stream miles with microcystins detected | 9% | EPA assessment |
| River and stream miles with cylindrospermopsin detected | 10% | EPA assessment |
| River and stream miles above the 300 ppb mercury criterion | 5% | About 82,000 miles |
| River and stream miles not assessed for the mercury fish-tissue metric | 74% | Fish meeting the minimum size requirement were mainly absent |
The share of miles exceeding the EPA enterococci benchmark decreased by 13 percentage points between 2013–14 and 2018–19. PFOS-exceedance river miles fell by as much as 7 percentage points during that period. These changes describe the EPA’s comparison between survey periods; they do not establish conditions in a particular local river.
Mercury remains a notable issue in fish tissue. Mercury was detected in all fish tissue plug samples in the EPA’s NRSA fish-tissue study. Fish in 5% of river and stream miles had concentrations above the 300 parts-per-billion criterion, equivalent to about 82,000 miles, while 21% of miles had concentrations that did not exceed the criterion. The fish-tissue analysis was based on 41,099 river miles, and 74% of river and stream miles were not assessed for this metric.
Physical habitat and riparian areas
Physical habitat statistics are stronger than the biological results. The EPA rated 68% of river and stream miles good for in-stream habitat, 22% fair, and 10% poor. More than two-thirds of miles were therefore good on this measure, even though biological indicators showed much larger poor-condition shares.
Streambed sediments were in good condition on 57% of river and stream miles, fair on 23%, and poor on 20%. Riparian vegetation cover was good on 56% of rivers and streams, fair on 17%, and poor on 27%. Riparian disturbance was rated good for 36% of riparian areas, fair for 42%, and poor for 22%.
Several physical-habitat measures improved between 2013–14 and 2018–19. Good-condition river and stream miles for riparian disturbance increased by 9 percentage points, and good-condition miles for streambed sediments increased by 6 percentage points. Poor-condition river and stream miles for in-stream fish habitat decreased by 4 percentage points. In the Coastal Plains ecoregion, good-condition in-stream habitat increased by 14 percentage points; in the Temperate Plains, it increased by 11 percentage points. The Upper Midwest moved in the opposite direction, with a 14-percentage-point decrease in good-condition in-stream habitat.
These indicators measure different parts of a river system. A reach can have good in-stream habitat while still showing poor nutrient or biological conditions. That distinction matters when interpreting conservation work: restoring banks, sediments, or channel structure is measurable progress, but it does not automatically mean that every ecological indicator has recovered.
Regional differences
National averages conceal substantial ecoregional variation. In the EPA report, the share of river and stream miles with good riparian disturbance condition ranged from 5% in the Northern Plains to 55% in the Western Mountains. Good-condition phosphorus miles ranged from 7% in the Temperate Plains to 67% in the Western Mountains.
The biological indicators also varied sharply. Good-condition benthic macroinvertebrate miles ranged from 9% in the Coastal Plains to 61% in the Western Mountains. Poor-condition fish community miles ranged from 17% in the Upper Midwest to 50% in the Coastal Plains.
| EPA indicator | Lowest reported ecoregional result | Highest reported ecoregional result |
|---|---|---|
| Good riparian disturbance condition | 5% in Northern Plains | 55% in Western Mountains |
| Good phosphorus condition | 7% in Temperate Plains | 67% in Western Mountains |
| Good benthic macroinvertebrate condition | 9% in Coastal Plains | 61% in Western Mountains |
| Poor fish community condition | 17% in Upper Midwest | 50% in Coastal Plains |
The figures are ecoregional results from the EPA assessment, not rankings of individual rivers or communities. They show why conservation priorities can differ: nutrient control, riparian protection, habitat repair, and biological recovery may have very different starting points from one region to another.
Restoration through the National Estuary Program
EPA’s National Results from the National Estuary Program reports more than 2.5 million acres restored or protected since 2000. Habitat efforts totaled 154,988.144 acres in 2025. The largest 2025 categories were forest or woodland habitat at 79,384.01 acres, forested wetland habitat at 17,063.39 acres, estuarine shoreline habitat at 12,480.88 acres, salt marsh habitat at 7,059.82 acres, riparian habitat at 5,111.4 acres, and in-stream habitat at 463.9 acres.
The same EPA results report 123,605.76 acres of habitat efforts in 2024. That year’s categories included 67,598.861 acres of forest or woodland habitat, 13,818.468 acres of forested wetland, 14,102.459 acres of riparian habitat, 7,071.927 acres of freshwater marsh, 6,086.65 acres of salt marsh, and 2,454.71 acres of in-stream habitat.
Other 2024 categories included 3,998.81 acres of agriculture or ranch land habitat, 2,772.441 acres of lake or pond habitat, 2,052.5 acres of shrub swamp, 1,179.7 acres of grassland, 692.641 acres of dune habitat, 572.1 acres of beach habitat, 9.16 acres of hard-bottom habitat, and 8.897 acres of submerged aquatic vegetation habitat. These are reported habitat-effort totals for the stated years, not a forecast of future restoration.
Dam removal and river reconnection
Dam removal is another measurable conservation strategy. In its June 2023 dam removal factsheet, American Rivers reported that more than 2,025 dams had been removed in the U.S. by June 2023, compared with more than 500,000 dams in the country. Less than 3% of U.S. dams were hydropower dams, less than 17% provided flood protection, and 85% were more than 50 years old. The factsheet also reported at least 87 dam failures in South Carolina during storms and hurricanes since 2015.
Examples in the American Rivers factsheet illustrate the scale of ecological effects. Seven dams on Alabama’s Coosa River helped drive more than 30 freshwater species extinct; historically, the river supported 147 fish species, 91 snail species, and 53 mussel species. Removal of Penobscot River dams opened 1,000 miles of habitat, and river herring runs increased from a few thousand to well over 2 million after two dams were removed. Two dams were removed from the Elwha River beginning in 2011. The Klamath River project involved four dams, while four dams had been removed from the Cuyahoga River since 2005, leaving a 40-mile stretch that canoeists could paddle to Lake Erie.
American Rivers reported 108 dams removed in 2024, tied for the most ever removed in a single year. Those removals reconnected more than 2,528 miles of rivers, and 27 states removed dams. Pennsylvania led with 27 removals, followed by Michigan with 10, while Minnesota and Virginia each had 7. These are reported 2024 results from American Rivers’ 2025 State of Dam Removals in the U.S., distinct from the earlier cumulative total measured through June 2023.