[marymkearney]

This is pretty scary. These dams look so shallow and easy to run. Thanks for the PSA.

Here's a cool US Army Corps of Engineers report on the remediation of dangerous and defective dams: https://apps.dtic.mil/sti/pdfs/ADA372898.pdf.

Pages 21-24 show how they fixed the deadly "roller" at Little Falls Dam outside Washington DC, 1988-1990. Quote:

"In periods of very heavy flow, when 0.9 to 1.5 m (3 to 5 ft) of water crest the dam, a strong roller, or undertow, condition is created (Figure 9). Between 1975 and 1983, 17 people drowned in the vicinity of the dam. Rafting or canoeing near or over the dam, they were caught in the undertow and submerged. Seeking to prevent further loss of life, the USACE began looking for solutions for this problem (Davis and George 1985)."