Guide 4 of 12

Dam records explained: hazard, condition and dates

References checked Oct 4, 2026.

Short answer: The federal National Inventory of Dams (NID) lists a "hazard potential" and, for many dams, a "condition assessment." Hazard potential is about what could happen downstream if a dam failed. It is not a rating of the dam's condition or of how likely it is to fail.¹ Condition values can be years old, so check the record's dates and ask the owner for the latest state inspection report.

What the NID is

The NID was developed by the U.S. Army Corps of Engineers.¹ Its records come from the agencies that submit dam data, and its fields describe each record "prior to the NID data transmittal by the submitting agency."¹ Each lake page on this site shows the NID record for the lake's dam, with the date of the record and the last inspection it reports. We match each record to a lake by its distance from the lake's outline in the USGS National Hydrography Dataset, and by name.² A dam's NID name doesn't always match the lake's name, so search by the NID ID shown on the lake page.³

Hazard potential

The NID defines hazard potential as a category for the potential hazard to the downstream area if the dam failed or was mis-operated, reflecting probable loss of life and economic, environmental and lifeline impacts. Its own definition adds: "The hazard potential does not speak to the condition of the dam or the risk of the dam failing."¹

So a "High" hazard dam may be in good shape. The label reflects possible harm downstream, not cracks or leaks.¹

Condition assessment

For many dams that the Corps does not own, the NID gives a condition assessment that indicates whether a deficiency is known.¹ The NID explains that a dam safety deficiency is an issue that could cause a failure, or a condition that does not meet minimum regulatory criteria, and that "poor" or "unsatisfactory" condition means a deficiency is recognized.¹ In Pennsylvania's NID records, the values include Satisfactory, Fair, Poor, Unsatisfactory, Not Rated and Not Available.³

The NID also has an "operational status" field. Its help text says Normal Operations applies to dams with a Satisfactory or Fair condition assessment, and it lists other statuses, such as Under Remediation, for dams with a Fair, Poor or Unsatisfactory assessment where a deficiency is recognized.¹

Why dates matter

Every NID record carries dates: when the record was updated, the last inspection reported, and sometimes when the condition was assessed. The last inspection date is the most recent inspection reported before the data were sent to the NID.¹ In the Pennsylvania records we downloaded, 1,234 of the 1,367 records sourced from Pennsylvania's dam program showed a record date of April 9, 2021.³ A five-year-old record can't tell you what an inspector found last spring.

That's why our lake pages show this note when a record is more than three years old: "This is an older record: USACE NID last updated it on [date]." Ask the owner for the newest inspection report.

Pennsylvania's own categories

Pennsylvania classifies dams by size (A, B, C) and hazard potential (1 to 4) under its dam safety rules.⁴ Category 1 means a substantial number of people at risk downstream; Category 4 means none expected and minimal damage.⁴ Pennsylvania's rules also define a "high hazard dam" as a dam located so that its failure would endanger populated areas downstream.⁴ These state categories decide which inspections, reports and plans the owner owes.⁴ They are not the same as the NID labels, and we never infer one from the other.

Emergency Action Plans

An Emergency Action Plan (EAP) is the dam owner's plan of action to reduce the potential for property damage and loss of life in an area affected by a dam failure or large flood.¹ Pennsylvania requires one for Category 1, 2 and 3 dams, approved by DEP and the Pennsylvania Emergency Management Agency.⁴ For Category 1 and 2 dams, the owner must post notices saying that copies of the EAP are available for review at the county and municipal emergency management offices.⁴ The NID's "EAP prepared" field shows Yes, No or Not Required as reported.¹ In most of the Pennsylvania-sourced records we use, that field is blank.³

How to look up any dam

1. Go to the National Inventory of Dams website and search by the dam's name or NID ID (for example, PA00777).
2. Read the hazard potential with the explainer above in mind.
3. Note the record date and the last inspection reported.
4. Ask the dam's owner for the latest state inspection report, the engineer's annual report if the dam is Category 1 or 2, and the EAP status.

Each lake page here links straight to the dam's NID page.

If an association owns the dam

The NID records each dam's owner type. In its own example, a dam owned by a lake association and a public utility is listed as "Private;Public Utility."¹ If a homeowners' association owns the dam, two items on its Pennsylvania resale certificate matter. One states any capital expenditures the association proposes for the current and next two fiscal years. The other states its reserves for capital expenditures, including any part set aside for a specific project.⁵ Read both next to the latest inspection report. Our guide to special assessments and private dams goes further.

What to ask, record by record

• Hazard High or Significant: "May I see the latest inspection report and the EAP status? Does the spillway meet its design flood?"
• Condition Fair, Poor or Unsatisfactory: "What is the current DEP status, and what repairs are planned and how are they funded?"
• Old record: "When was the dam last inspected, and may I see that report?"

FAQ

Does a High hazard label mean the dam is likely to fail?

The hazard label isn't a safety rating. The NID says hazard potential does not speak to the condition of the dam or the risk of failure.¹ Ask the owner for the latest inspection report.

Why does the record say 2021?

Many Pennsylvania records in the NID were last updated on April 9, 2021.³ Ask the owner for anything newer.

What is an EAP?

A dam owner's emergency plan. Pennsylvania requires one for Category 1, 2 and 3 dams and requires it to be reviewed every five years or as the guidelines say.⁴

Where do I find the Pennsylvania category?

Ask the dam's owner; the category drives the owner's inspection and reporting duties.⁴ The federal records we use don't include it, and we never guess it from the NID's own labels.

Lakes where this comes up

• Arrowhead LakeMonroe County
• Gold Key LakePike County
• Big Bass LakeLackawanna County
• Edinboro LakeErie County
• Deer LakeFayette County
• Indian Mountain LakeMonroe County