Aging Dams in the US
Aging Dams in the US
AP report highlights Dam problems: New York dams included in report
The Associated Press just released a two-year study on the health and safety of dams in the US, and regional and it appears that regional state-specific summaries will be coming out in the week or so. Recently summaries have already appeared in the news for deficient dams in New England, and Connecticut.
The AP report is primarily focused on intermediate and high-hazard dams because these have the most potential to cause damage if they fail. Significant in their reporting is the condition of dams in the inventory.
Virtually all states in the US have Dam Safety programs, and these programs inspect dams and then write reports - hopefully concerns raised in these reports are addressed by dam owners. In a general way these reports allow for an understanding of the condition of the dam, and in some cases they were able to identify chronic problems. The AP obtained inspection reports for thousands of dams in the nation.
The Associated Press report includes the mapped occurrence of dams in the US, where data are available, and their condition (screen shot of interactive map in AP article)..
Their review of inspection reports from 44 states showed that 1,688 high-hazard dams have been rated in poor or unsatisfactory condition as of 2018. They note:
One of the most common problems for aging dams are spillways incapable of handling an extreme rainfall event. If water can’t escape quickly enough through spillways, it could flow over the top of a dam, which increases the probability of rapid erosion that can cause it to collapse.
Thus we come back to the issue that some dams constructed decades ago, are not ready or capable of handling intense precipitation events.
Some of the dams of concern in the initial AP report are in the Mohawk Watershed including the Harrower Pond Dam in Amsterdam. The report highlights an apparent issue with the Lake Sebago Dam (DEC Dam ID#: 196-0332 - read the report here) that appear to have underfit spillways, and these have been identified NY the NYSDEC for some time now. Lake Sebago is the largest lake in Harriman State Park.
The Association of State Dam Safety Officials released its 2019 report in April on the national need for dam rehabilitation, and the suggest that the total cost estimate for non-federal dams is $66 billion, and for non-federal, high-hazard potential dams is $20 billion.
A new $10 million Federal Emergency Management Agency (FEMA) grant program addresses high hazard dams that problematic, as recently reported. While a start, this appears to be a drop in the bucket. New York State received one of the the largest awards from this program of more than $1.2 million. NY will take applications 150 eligible dams.
The AP report is likely to get some attention in the near future, as it should. Some of the deficiencies in the report are related to lack of inspection and not necessarily impairment. One clear message here is that we have a lot of dams in the nation and many are problematic. The cost to address deficiencies appears to be enormous.
“Most people have no clue about the vulnerabilities when they live downstream from these private dams,” said Craig Fugate, a former administrator at the Federal Emergency Management Agency. “When they fail, they don’t fail with warning. They just fail, and suddenly you can find yourself in a situation where you have a wall of water and debris racing toward your house with very little time, if any, to get out.” (AP report).
An important message here is that local knowledge and local concerns can go a long way to getting attention focussed on certain dams that may present a hazard.
This and other Notes from a Watershed are available at: https://mohawk.substack.com/