In the United States, there are over 92,000 dams according to the National Inventory of Dams. Among these, approximately 17,000 dams are classified as having high hazard potential, meaning their failure could result in significant loss of life and property damage.

While specific numbers regarding how many of these dams currently need inspection are not readily available, the American Society of Civil Engineers (ASCE) has highlighted ongoing concerns about aging infrastructure and the need for increased inspections and maintenance. The ASCE's 2025 report indicates that many dams are over 60 years old and require urgent attention.

Overall, while we know there are thousands of dams that require inspection, the exact number needing immediate attention is difficult to quantify without specific state or federal reports detailing their conditions.

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As of 2025, there are over 222,000 bridges in the United States that require major repair work or replacement, which represents about 36% of all U.S. bridges 1. This indicates a significant number of municipalities across the country have bridges that need inspection and maintenance.

The American Road and Transportation Builders Association (ARTBA) reports that many of these bridges are aging, with a substantial portion rated as structurally deficient. This situation necessitates regular inspections to ensure safety and functionality.

While specific data on the number of municipalities with bridges needing inspection isn't detailed, it's clear that a large portion of the nation's infrastructure is in need of attention, affecting countless communities nationwide.

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Municipalities in the U.S. typically conduct inspections of underwater infrastructure based on specific guidelines and standards. Here’s a general overview of the inspection frequency:
1.    Bridges: Under the National Bridge Inspection Standards (NBIS), underwater inspections for bridges are required at a maximum interval of 60 months (5 years) for elements that cannot be accessed without diving equipment. Routine above-water inspections are conducted every 24 months.
2.    Dams: Inspections for dams can vary widely, but they are often required every 1 to 5 years, depending on the type and condition of the dam. Inspections may also be conducted after significant weather events.
3.    Water Infrastructure: For water pipelines and other related infrastructure, inspections can be continuous or occur every 1 to 5 years, often dictated by local regulations and the condition of the infrastructure.
4.    Emergency Inspections: In addition to scheduled inspections, municipalities often conduct emergency inspections after severe weather events or other incidents that may impact the integrity of underwater structures.

Overall, the frequency of inspections is influenced by factors such as the type of infrastructure, environmental conditions, and regulatory requirements, ensuring that safety and functionality are maintained.
 

The exact number of municipalities in the United States with underwater infrastructure that requires inspection is not clearly defined in available data. However, many municipalities, especially those near coastlines or with significant water management systems, have underwater infrastructure such as:
o    Water intakes and outfalls
o    Sewage systems
o    Bridges and culverts
These infrastructures often require regular inspections to ensure safety and functionality. For instance, the American Society of Civil Engineers has highlighted the need for frequent inspections of aging infrastructure, including dams and levees, which are critical for flood management.

While specific statistics on the number of municipalities needing inspections are scarce, it's clear that a significant number of cities and towns across the U.S. face challenges related to their underwater infrastructure, particularly in areas prone to flooding or with aging systems 

In the United States, there are several municipalities located below sea level, primarily in California and Louisiana. Here are some notable examples:
1.    New Orleans, Louisiana: Parts of the city are approximately 6 to 8 feet below sea level.
2.    Indio, California: This city is about 18 meters (59 feet) below sea level.
3.    Calipatria, California: Located around 180 feet (55 meters) below sea level, it is one of the lowest cities in the U.S.
4.    Bombay Beach, California: This small community is about 69 meters (226 feet) below sea level.
Overall, there are about 20 municipalities in the U.S. that are officially recognized as being below sea level, with the majority of them situated in California's Salton Sink area 1

Determining the exact number of municipalities in the United States with below-water-level infrastructure that requires inspection is challenging. However, several key cities are notably at risk due to their geographical positions and existing infrastructure challenges.
1.    New Orleans, Louisiana: This city is famously below sea level and relies heavily on levees and pumps to manage water. The infrastructure here is under constant scrutiny due to its vulnerability to flooding and rising sea levels.
2.    Miami, Florida: Parts of Miami are also below sea level, and the city faces increasing flooding risks, especially during high tides. Infrastructure improvements are ongoing, but many areas still require significant inspection and upgrades.
3.    Houston, Texas: While not entirely below sea level, Houston is experiencing significant land subsidence, which exacerbates flooding risks. The city has a substantial amount of infrastructure that needs regular inspection due to these challenges.
4.    Other Coastal Cities: Many coastal cities, including those in California and the Gulf Coast, are experiencing rising sea levels and increased flooding, necessitating inspections of their infrastructure.
Overall, while specific numbers are not readily available, it's clear that numerous municipalities, particularly those along the Gulf and Atlantic coasts, are facing significant infrastructure challenges related to being below or near water level 1