This map layer portrays major dams of the United States, including Puerto Rico and the U.S. Virgin Islands. The map layer was created by extracting dams 50 feet or more in height, or with a normal storage capacity of 5,000 acre-feet or more, or with a maximum storage capacity of 25,000 acre-feet or more, from the 79,777 dams in the U.S. Army Corps of Engineers National Inventory of Dams. This is a replacement for the April 1994 map layer.

The Dams dataset is a representation of the National Inventory of Dams (NID), maintained and published by the U.S. Army Corps of Engineers, in cooperation with the Association of State Dam Safety Officials, the states, territories, and federal agencies. It is also part of the U.S. Department of Transportation (USDOT)/Bureau of Transportation Statistics (BTS) National Transportation Atlas Database (NTAD). The Dams dataset (NID) includes all known dams of the United States and its territories, that meet the federal definition of a dam. Dams where downstream flooding would likely result in loss of human life (high hazard potential). Dams where downstream flooding would likely result in disruption of access to critical facilities, damage to public and private facilities, and require difficult mitigation efforts (significant hazard potential). Dams that meet minimum height and reservoir size requirements, even though they do not pose the same level of life or economic risk as those above - these low hazard potential dams equal or exceed 25 feet in height and exceed 15 acre-feet in storage, or equal or exceed 50 acre-feet storage and exceed 6 feet in height. The database contains more than 70 data fields for each dam. This includes the dam's location, size, purpose, type, last inspection, and regulatory facts. The information is updated periodically by the state and federal agencies, reflected by the "Data Last Updated Date". For more information on dams, visit the NID web site at https://nid.sec.usace.army.mil/#. A data dictionary, or other source of attribute information, is accessible at https://doi.org/10.21949/1529016

To access this data:

This data is available for licensing to anyone interested in understanding risks around hazardous dams. To request access, click REQUEST ACCESS or email Ken Romano at kromano@ap.org.

Update 2/20/20 This data has been updated with the following: * The dams_in_nid_state_reports.csv file has been updated to include a column for owner_name, as it was provided by the states. Nearly 30,000 dam entries did not have an owner_name provided. Owner names may need deduplication, due to alternate name spellings in the data provided. * New findings regarding dams lacking emergency action plans in Southeastern states, in the Findings section.

Overview

The nation’s dams are on average more than a half-century old and, in some cases, weren’t designed to handle the amount of water that could result from the increasingly intense rainstorms of a changing climate. Yet almost no information has been publicly available about the condition of these dams. Since 2002, the U.S. Army Corps of Engineers has redacted inspectors’ condition assessments from its National Inventory of Dams over security concerns; the Corps makes publicly available only the hazard rating of certain dams, which assesses the potential for loss of human life or economic and environmental damage should a dam fail.

The Associated Press has created an exclusive dataset that fills in those information gaps for a subset of dams across the country. It found at least 1,688 high hazard dams that are in poor or unsatisfactory condition, and in places where failure is likely to kill at least one person.

The AP’s analysis is based on data obtained through dozens of state open-records requests, which allowed the AP to compile a dataset that contains both hazard levels and condition ratings for dams in 45 states and Puerto Rico. Five states – Alabama, Illinois, Maryland, New Jersey and Texas – did not fully comply with the records request for reasons described in the methodology and caveats sections below. (Iowa provided all requested documents but had no dams listed as both high hazard and in poor or unsatisfactory condition).

For the subset of high hazard dams in poor or unsatisfactory condition, the AP is sharing state inspection reports and local emergency action plans that provide additional details about the problems of some particular dams, their potential to inundate nearby areas if they were to catastrophically fail and plans to respond should there be a disaster.

The AP also analyzed the annual budget and staffing levels for dam safety offices in each state using data from an annual survey conducted by the U.S. Army Corps of Engineers.

Additionally, the AP obtained data from the Federal Emergency Management Agency and state dam safety offices about $10 million of federal grants that were awarded this fall to 26 states. The grants are the first under the new Rehabilitation of High Hazard Potential Dams Grant Program. The money is to go toward risk assessments and engineering designs to repair high hazard dams that have failed to meet safety standards and pose an unacceptable risk to the public.

Findings

The AP’s analysis found: * Update 2/20/20: As storms, floods, and dam breaches have hit Mississippi in recent weeks, emergency action plans have been important in denoting whom to contact, who and what has been in danger, and how to handle a dam emergency. An Associated Press analysis of data received in summer 2018 from state and federal agencies found that 111 of the 375 high hazard dams in Mississippi were missing emergency action plans – nearly 30 percent. Some other Southern states had even more dams lacking emergency plans. In North Carolina, 578 of the 1,277 of high hazard dams, nearly half of them, had no emergency plan. In Georgia, 259 of the 623 were missing emergency plans. In fact, in at least seven Southeastern states, at least 20 percent of the high hazard dams were missing emergency plans as of summer 2018. * There are at least 1,688 high hazard dams in poor or unsatisfactory condition in 44 states and Puerto Rico. These potentially dangerous dams account for about 19% of the more than 8,800 high hazard dams for which the AP obtained condition ratings. Iowa listed no high hazard dams as poor or unsatisfactory. * More than half of the dams in the AP’s list of high hazard facilities in poor or unsatisfactory condition are privately owned, which can create challenges for state regulatory agencies seeking to enforce needed repairs or improvements. * About half of the dams in the AP’s list of high hazard facilities in poor or unsatisfactory condition are used primarily for recreation, though that may not have been the purpose for which the dams originally were built. Nearly one-fifth of the dams are used primarily for flood control. * Georgia had 198 high hazard dams in poor or unsatisfactory condition, the highest number among all states for which the AP obtained data. North Carolina was second with 168 such dams, followed by Pennsylvania with 145, Mississippi with 132, Ohio with 124 and South Carolina with 109. * As of summer 2018, more than a quarter of the high hazard dams in poor or unsatisfactory condition had inspection reports that were more than 1.5 years out of date, and about 35% didn’t have emergency action plans documenting procedures in case of the dam’s failure. Note that some of those dams could have undergone inspections or adopted emergency plans since then. * Budget and staffing levels for state dam safety offices declined following the Great Recession and have generally risen since then. California, which has the nation’s largest dam safety program, boosted its budget from around $13 million in 2017 to $20 million this past year and increased its full-time staff positions from 63 to 77 following the failure of the Oroville dam spillway in 2017. * Thirteen states and Puerto Rico were spending less on dam safety programs in their 2019 fiscal years than they did in 2011, and 11 states had fewer full-time positions in their programs as of last year. Alabama is the only state with no dam safety program. * States often have small dam safety staffs to oversee large numbers of dams. Indiana is representative of many states, with a $500,000 budget and six full-time staff positions for a dam safety office that regulates 840 dams.

Localization ideas

The AP’s database of dam inspection records collected from state agencies can be filtered to find the high hazard dams in poor or unsatisfactory condition in your state.

That data also provides key details that can be used for further reporting about the facilities, including their names, exact locations, identification numbers, the year they were built and the dates of their most recent inspections and emergency action plans. For many of these dams, the AP also has provided documents detailing their most recent inspection reports and emergency plans. The datasets on state dam safety program budgets and personnel also can be used to examine how a state’s regulatory oversight has changed over time.

Use the entire dams dataset to map all the dams in your state, find out what share of dams in your state are high hazard and in poor or unsatisfactory condition, and to do further analysis on ownership and purpose.

Some questions to ask:

Are there nearby dams in poor condition that could cause widespread damage if they failed? * Emergency action plans include potential inundation zones if a high hazard dam were to fail. For example, one community potentially in harm’s way is Norwood, Massachusetts, a Boston suburb of nearly 30,000 people. The high hazard dam on nearby Willett Pond is rated in poor condition, primarily because its spillway is capable of handling only about 13% of the water flow from a serious flood, according to a recent inspection report. More than 1,300 properties with structures lie within the dam’s potential inundation zone, including several shopping centers, at least two elementary schools, more than 70 roads and two railroads.

Are there high hazard dams for which there are concerns about whether the structure could withstand a natural disaster? * One example of this is in Alaska, which has five high hazard dams in poor or unsatisfactory condition. Several inspections raised concerns about seismic activity. Inspection reports for the Lower and Upper Wrangell dams note that neither dam “is found to be stable during a seismic event.”

Are there dams with outdated or missing emergency action plans? * One example of this is in New Mexico, where many dams had no emergency action plans as of summer 2018. Many dams there also were rated poor because authorities had no design plans for them. In addition, inspection reports for the majority of the dams mentioned that the dams did not meet standards for a probable maximum precipitation event.

How have state officials responded to previous concerns about the safety of dams? * Following widespread dam failures during intense rainstorms in 2015-2016, South Carolina tripled the personnel in its dam safety program and increased its budget from about $260,000 annually to about $1 million. By contrast, Missouri took no action after a mountaintop reservoir failed in 2005, injuring a park superintendent’s family in the resulting flash flood. Though the governor proposed to significantly expand the number of dams subject to state inspections, the legislation failed to pass.

Interactive

The AP is making an interactive map made in partnership with ESRI for this dataset available early to aid in reporting.

The interactive displays the 1,688 dams in the dataset that are high hazard and in poor or unsatisfactory condition. Coloring is determined by how overdue its last inspection, as of July 2018, is from its expected inspection frequency. By clicking on individual dams, more detailed information from the AP dataset

This map layer portrays major dams of the United States, including Puerto Rico and the U.S. Virgin Islands. The map layer was created by extracting dams 50 feet or more in height, or with a normal storage capacity of 5,000 acre-feet or more, or with a maximum storage capacity of 25,000 acre-feet or more, from the 79,777 dams in the U.S. Army Corps of Engineers National Inventory of Dams. This is a replacement for the April 1994 map layer.

This dataset is a subset (containing records of the dams present in the state of Florida) of The National Inventory of Dams. Congress first authorized the US Army Corps of Engineers to inventory dams in the United States with the National Dam Inspection Act (Public Law 92-367) of 1972. The NID was first published in 1975, with a few updates as resources permitted over the next ten years. The Water Resources Development Act of 1986 (P.L. 99-662) authorized the Corps to maintain and periodically publish an updated NID, with re-authorization and a dedicated funding source provided under the Water Resources Development Act of 1996 (P.L. 104-3). The Corps also began close collaboration with the Federal Emergency Management Agency (FEMA) and state regulatory offices to obtain more accurate and complete information. The National Dam Safety and Security Act of 2002 (P.L. 107-310) reauthorized the National Dam Safety Program and included the maintenance and update of the NID by the Corps of Engineers. The most recent Dam Safety Act of 2006 reauthorized the maintenance and update of the NID. The NID consists of dams meeting at least one of the following criteria; 1) High hazard classification - loss of one human life is likely if the dam fails, 2) Significant hazard classification - possible loss of human life and likely significant property or environmental destruction, 3) Equal or exceed 25 feet in height and exceed 15 acre-feet in storage, 4) Equal or exceed 50 acre-feet storage and exceed 6 feet in height. The goal of the NID is to include all dams in the U.S. that meet these criteria, yet in reality, is limited to information that can be gathered and properly interpreted with the given funding. The Inventory initially consisted of approximately 45,000 dams, which were gathered from extensive record searches and some feature extraction from aerial imagery. Since continued and methodical updates have been conducted, data collection has been focused on the most reliable data sources, which are the various federal and state government dam construction and regulation offices. In most cases, dams within the NID criteria are regulated (construction permit, inspection, and/or enforcement) by federal or state agencies, who have basic information on the dams within their jurisdiction. Therein lies the biggest challenge, and most of the effort to maintain the NID; periodic collection of dam characteristics from 49 states (Alabama currently has no dam safety legislation or formal dam safety program), Puerto Rico, and 18 federal offices. The Corps resolves duplicative and conflicting data from the 68 data sources, which helps obtain the more complete, accurate, and updated NID.

All charts, queries and maps reflect the most current 2018 National Inventory of Dams (NID) database. State and federal dam regulators provided their data from May to November 2018 for inclusion in the 2018 database.

The Dams dataset is part of the U.S. Department of Transportation (USDOT)/Bureau of Transportation Statistics's (BTS's) National Transportation Atlas Database (NTAD). This map layer portrays major dams of the United States, including Puerto Rico and the U.S. Virgin Islands. The map layer was created by extracting dams 50 feet or more in height, or with a normal storage capacity of 5,000 acre-feet or more, or with a maximum storage capacity of 25,000 acre-feet or more, from the 79,777 dams in the U.S. Army Corps of Engineers National Inventory of Dams. This is a replacement for the April 1994 map layer.

These data are intended for geographic display and analysis at the national level, and for large regional areas. The data should be displayed and analyzed at scales appropriate for 1:2,000,000-scale data. No responsibility is assumed by the National Atlas of the United States in the use of these data. Supplemental_Information: In the online National Atlas of the United States Map Maker, at scales smaller than 1:4,850,000 the data is thinned for display purposes. For scales between 1: 4,850,000 and 1:22,000,000, dams are only shown if they have a height of 500 feet or more, or a normal storage capacity of 50,000 acre-feet or more, or a maximum storage capacity of 250,000 acre-feet or more (1280 dams). At scales smaller than 1:22,000,000, dams are only shown if they have a height of 5000 feet or more, or a normal storage capacity of 500,000 acre-feet or more, or a maximum storage capacity of 2,500,000 acre-feet or more (290 dams).

This map is intended as a component of the Map Tour - "U.S. Army Corps of Engineers (USACE) Dams in the ACF"This map displays the 5 dam projects USACE has within the Apalachicola, Chattahoochee, and Flint (ACF) River Basin.

This map layer includes the locations of over 500 majors dams in New York State. The information in the map layer was provided by the U.S. Army Corps of Engineers (USACE). The original dam information came from the National Inventory of Dams (NID) which was produced by USACE in cooperation with FEMA's National Dam Safety Program. The full NID contains over 75,000 dams and is used to track information on the country's water control infrastructure. This data set portrays major dams of New York State. The data set was created by extracting dams 50 feet or more in height, or with a normal storage capacity of 5,000 acre-feet or more, or with a maximum storage capacity of 25,000 acre-feet or more, from the 75,187 dams in the U.S. Army Corps of Engineers National Inventory of Dams.

This map layer portrays major dams of the United States, including Puerto Rico and the U.S. Virgin Islands. The map layer was created by extracting dams 50 feet or more in height, or with a normal storage capacity of 5,000 acre-feet or more, or with a maximum storage capacity of 25,000 acre-feet or more, from the 79,777 dams in the U.S. Army Corps of Engineers National Inventory of Dams. This is a replacement for the April 1994 map layer.

This dataset provides a locational map of 75,187 dams in the conterminous United States. The National Inventory of Dams was originally developed by the U.S. Army Corps of Engineers and the Federal Emergency Management Agency. It was developed to track dam related problem areas. This database shows the age of the dam, number of people living downstream, and some inspection information. The dam inspection data also includes location information (such as latitude, longitude and nearest town), a description of a dam's size, reservoir capacity, the owner and the regulatory oversight agency. For distribution with BASINS v.2.0, the data layer was prepared in Arcview shape file format. The National Inventory of Dams was originally developed by the U.S. Army Corps of Engineers and the Federal Emergency Management Agency. It was developed to track dam related problem areas. This database shows the age of the dam, number of people living downstream, and some inspection information. The dam inspection data also includes location information (such as latitude, longitude and nearest town), a description of a dam's size, reservoir capacity, the owner and the regulatory oversight agency. Intended use of data: This data set was prepared to support the U.S. EPA BASINS (Better Assessment Science Integrating Point and Nonpoint Sources) System. The dam point coverage provides Geographic Information System GIS) applications with a valuable data layer for base mapping of dam locations. These locations are used in numerous types of analysis, e.g., stream network analysis, hydrologic flow.

Source:

This EnviroAtlas dataset is a summary of the National Dams Inventory data from 2009 survey. The file contains counts of inventoried dams by 12-digit hydrologic units codes (March 2011) and total maximum storage capacity in millions of gallons. This dataset was produced by the US EPA to support research and online mapping activities related to EnviroAtlas. EnviroAtlas (https://www.epa.gov/enviroatlas) allows the user to interact with a web-based, easy-to-use, mapping application to view and analyze multiple ecosystem services for the contiguous United States. The dataset is available as downloadable data (https://edg.epa.gov/data/Public/ORD/EnviroAtlas) or as an EnviroAtlas map service. Additional descriptive information about each attribute in this dataset can be found in its associated EnviroAtlas Fact Sheet (https://www.epa.gov/enviroatlas/enviroatlas-fact-sheets).

This dataset is generated from Dam Inventory. The inventory is managed by the VT DEC's Dam Safety and Hydrology Section and contains information about Vermont's dams. The Dam Safety and Hydrology Section manages programs that promote dam safety and protection of flows in Vermont's rivers and streams. The inventory supports them in this effort by tracking physical attributes, managing construction (permits) and inspection information, and reporting to the US Army Corps of Engineers.

National Inventory of DamsThis feature layer, utilizing National Geospatial Data Asset (NGDA) data from the U.S. Army Corps of Engineers (USACE), displays dams within the United States, Puerto Rico and Guam. Per the USACE, "The National Inventory of Dams (NID) consists of dams meeting at least one of the following criteria:Dams where downstream flooding would likely result in loss of human life (high hazard potential).Dams where downstream flooding would likely result in disruption of access to critical facilities, damage to public and private facilities, and require difficult mitigation efforts (significant hazard potential).Dams that meet minimum height and reservoir size requirements, even though they do not pose the same level of life or economic risk as those above – these dams are typically equal to or exceed 25 feet in height and exceed 15 acre-feet in storage, or equal to or exceeding 50 acre-feet storage and exceeding 6 feet in height.The NID does not yet contain all dams in the U.S. that meet these criteria. Continued, routine updates to the NID and enhanced data collection efforts, focused on the most reliable data sources (primarily the many federal and state government dam regulatory programs), will help capture these dams and result in a more robust dataset over time."Hoover, Davis & Glen Canyon DamsData currency: This cached Esri federal service is checked weekly for updates from its enterprise federal source (Dams) and will support mapping, analysis, data exports and OGC API – Feature access.NGDAID: 160 (National Inventory of Dams)OGC API Features Link: (National Inventory of Dams - OGC Features) copy this link to embed it in OGC Compliant viewersFor more information, please visit: National Inventory of DamsSupport Documentation: Reference DocumentsFor feedback please contact: Esri_US_Federal_Data@esri.comThumbnail courtesy of: Esri Basemaps ImageryNGDA Data SetThis data set is part of the NGDA Water - Inland Theme Community. Per the Federal Geospatial Data Committee (FGDC), Water - Inland is defined as the "interior hydrologic features and characteristics, including classification, measurements, location, and extent. Includes aquifers, watersheds, wetlands, navigation, water quality, water quantity, and groundwater information."For other NGDA Content: Esri Federal Datasets

This dataset shows maximum conservation pool or is a reasonable representation of the boundaries for reservoirs and lakes owned and operated by USACE. Data is from USACE Districts.

This data set represents major dams of the United States, including Puerto Rico and the U.S. Virgin Islands. The map layer was created by extracting dams 50 feet or more in height, or with a normal storage capacity of 5,000 acre-feet or more, or with a maximum storage capacity of 25,000 acre-feet or more, from the 79,777 dams in the U.S. Army Corps of Engineers National Inventory of Dams.

A Brief History of the NIDThe site we see today was first conceptualized in the 1970s when Congress tasked the U.S. Army Corps of Engineers (USACE) with identifying, inspecting, and inventorying dams in the U.S (National Dam Inspection Act, PL 92-367).Early data gathering for the NID was led by USACE, which published the first inventory in 1975. By 1982, the NID included 68,153 dam records gathered from dam inspections, extensive record searches, and some feature extraction from aerial imagery. These NID databases were available on diskettes and compact discs.In the late 1990s, the NID was transitioned to a web-based platform and viewing the data on a map. Gathering data on dams also transitioned during this time - the most accurate data was now coming from states, territories, and federal agencies. This transition aligned with the establishment of the National Dam Safety Program.Information Available in the NIDSince transitioning to a web-based platform, site visitors have been able to download or export certain data. The NID is currently the only place to find and download national data at such a detailed level.Today, the database contains information for more than 91,000 dams that meet the following criteria:Dams where a failure or mis-operation will likely result in loss of human life (high hazard potential).Dams where a failure or mis-operation would likely result in disruption of access to critical facilities, damage to public and private facilities, and require difficult mitigation efforts (significant hazard potential).Dams that meet minimum height and reservoir size requirements, even though they do not pose the same level of life or economic risk as those above – these dams are equal to or exceed 25 feet in height and exceed 15 acre-feet in storage, or equal to or exceeding 50 acre-feet in storage and exceeding 6 feet in height.The NID does not yet contain all dams in the U.S. that meet these criteria. Continued, routine updates to the NID and enhanced data collection efforts, focused on the most reliable data sources (primarily the many federal and state government dam regulatory programs), will help capture these dams and result in a more robust dataset over time.National Inventory of DamsContact NID at NID@usace.army.mil

This dataset represents the dam density and storage volumes within individual, local NHDPlusV2 catchments and upstream, contributing watersheds based on National Inventory of Dams (NID) data. Attributes were calculated for every local NHDPlusV2 catchment and accumulated to provide watershed-level metrics.(See Supplementary Info for Glossary of Terms). The NID database contains information about the dams location, size, purpose, type, last inspection, regulatory facts, and other technical data. Structures on streams reduce the longitudinal and lateral hydrologic connectivity of the system. For example, impoundments above dams slow stream flow, cause deposition of sediment and reduce peak flows. Dams change both the discharge and sediment supply of streams, causing channel incision and bed coarsening downstream. Downstream areas are often sediment deprived, resulting in degradation, i.e., erosion of the stream bed and stream banks. This database was improved upon by locations verified by work from the USGS National Map (Jeff Simley Group). It was observed that some dams, some of them major and which do exist, were not part of the 2009 NID, but were represented in the USGS National Map dataset, and had been in the 2006 NID. Approximately 1,100 such dams were added, based on the USGS National Map lat/long and the 2006 NID attributes (dam height, storage, etc.) Finally, as clean-up, a) about 600 records with duplicate NIDID were removed, and b) about 300 records were removed which represented the same location of the same dam but with a different NIDID, for the largest dams (did visual check of dams with storage above 5000 acre feet and are likely duplicated - about the 10,000 largest dams) . The (dams/catchment) and (dam_storage/catchment) were summarized and accumulated into watersheds to produce local catchment-level and watershed-level metrics as a point data type

This map provides detailed information about dams (e.g. uses, capacity, ...) in South America.For more information, visit FAO AQUASTAT Dams Geo-referenced database: www.fao.org/nr/water/aquastat/dams/index.stm

This dataset provides a locational map of dams across the Tongass National Forest in Alaska. The National Inventory of Dams was originally developed by the U.S. Army Corps of Engineers and the Federal Emergency Management Agency. It was developed to track dam related problem areas. This database shows the age of the dam, number of people living downstream, and some inspection information. The dam inspection data also includes location information (such as latitude, longitude and nearest town), a description of a dam's size, reservoir capacity, the owner and the regulatory oversight agency. Uploaded to AGOL from the r10_tnf database in March, 2024. Not sync-enabled.This layer feeds the Long Range Transportation Plan Workshop Map web map and consumes the TNF dams feature layer.