The Dam Rules

by Gayle on January 24, 2012

Albemarle County Virginia LakeQuite often when I discuss with prospective farm and land buyers their criteria for a farm, I hear that they would like to have a lake or pond on the property.  No doubt, lakes and ponds can be a great source of enjoyment but they also require a lot of work to maintain.  Depending on the size of the lake, the lake’s dam may have to meet the Virginia Dam Safety Regulations and have annual inspections.

Here are the guidelines for dams which do not fall under the dam safety regulations:

  • the dam is less than six feet high.
  • the dam is used primarily for agricultural purposes and has a maximum capacity of less than 100-acre-feet or the dam is less than 25 feet tall.
  • the dam is less than 25 feet high and the lake’s maximum capacity is less than 50 acre-feet.
  • the dam is higher than 25 feet but the maximum capacity of the lake is less than 15 acre-feet.

How do you know if the lake that you are purchasing is subject to the dam safety regulations?   In the Charlottesville area (Albemarle, Nelson, Fluvanna & Louisa Counties), the regulatory agency for dam safety is the Thomas Jefferson Soil and Water Conservation District.   I strongly suggest you contact them.   In Madison, Greene, Orange, Culpeper and Rappahannock Counties the regulatory board is the Culpeper Soil and Water Conservation District.   The men and women that work at these agencies have a vast amount of knowledge and are always willing to help you learn about water and conservation practices to help keep your property not only beautiful, but environmentally friendly and most importantly… safe.

Dams can be compromised if trees are allowed to grow on them.   Ideally, dams should have a thick cover of grass and be mowed a couple of times of year to prevent trees & shrubs from taking over.   The trees’ roots are the problem.   As long as the tree is alive and healthy, it generally does no harm.   If the tree should die, then the roots begin to decay, leaving a cavity within the dam.  Over time this may cause leakage through the dam.   A more sudden and observable breach in the dam is if a tree should blow or fall over pulling up its rootball and leaving a much larger cavity in the dam.  Beaver Obviously critters such as groundhogs, beavers and muskrats can be detrimental to the dam structure as well.

If you are considering purchasing a property that has a lake with trees growing in the dam, you should consult with an engineer to understand the extent and cost of removing the trees.  Obviously there becomes a point where you shouldn’t just cut the trees down without having other measures in place to take care of the decaying roots.  The Virginia Department of Conservation and Recreation has a great article about Vegetation, Erosion and Dams on their site.

Now suppose the property that you are considering purchasing has a wonderful large lake on it that does not fall into the exempt category, what should you do?  Definitely contact the agencies listed above prior to purchasing the property.  You can find out in advance if there are any upcoming issues that may need to be addressed to keep the dam in compliance.   This even includes if a development is scheduled to be built downstream from your property, your dam’s hazard potential may be reclassified and need to meet more stringent regulations for future inspections AT YOUR EXPENSE.

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