Sand characteristics in bunkers will always be variable, no matter how intense the maintenance regime. That is part of the game – dig your feet in, gauge the lie and hit the appropriate shot! That said, when bunkers are extremely firm or excessively soft, it can frustrate golfers beyond the normal irritation of playing from a bunker. These extremes are the conditions courses want to avoid, but identifying them is subjective – at least until now. The USGA GS3™ ball can be a great tool to objectively measure bunker firmness. This data can help superintendents decide when adjustments should be made and whether modifications produced the desired result.
USGA agronomists have been using the GS3 to measure bunker sand firmness for several years in greenside bunkers in a variety of climates and at courses with varying maintenance budgets. The goal is not managing to a specific value, but rather to use the tool to avoid extremes. Avoiding the extremes leads to happier golfers who are more likely to return for more golf! With that in mind, USGA agronomists have seen a wide range of acceptable firmness values, usually from as low as 0.500 to as high as 0.900 inch. Values less than 0.500 inch may indicate that conditions are extremely firm and golfers will be more likely to have their club bounce off the surface rather than glide through the sand. Conversely, if values exceed 0.900 inch, golf balls are more likely to plug and result in the dreaded “fried-egg” lie.
When collecting measurements, plan to perform a drop test in a minimum of five spots in the flat area of greenside bunkers. Measuring won’t work well on bunker slopes. Use the average of five or more spots to determine if the bunker or specific areas of the bunker need to be modified. For example, if the average is 0.400 inch, the bunker is probably too firm and the sand depth should be inspected. If there is less than 4 inches of sand, adding sand to achieve a minimum depth of 6 inches in the bunker floor will very likely improve conditions. If the sand is deeper than 4 inches and is still too firm, then some form of “fluffing” may be sufficient to soften conditions. One example where this worked well was during preparations for the U.S. Mid-Amateur Championship at Troon Country Club in the fall of 2025.
If GS3 values exceed 0.900 inch, some method to firm the sand may be appropriate. Adding water and wheel packing is one method. A vibratory plate compactor is another option for increasing firmness. You might also consider adding a different sand to the bunkers to widen the particle size distribution and help improve firmness. However, these methods are all very labor intensive and certainly not appropriate for all courses. In some cases, irrigation, rain and time will result in natural firming.
While bunkers are meant to penalize errant shots, the sand shouldn’t be so hard and compacted that the average player struggles to play a normal bunker shot, or so soft that there are lots of golf balls getting buried in the sand. The GS3 is a tool that can help your course avoid the extremes. For more information on bunker maintenance or any other issues at your course, please reach out to your regional USGA agronomist.
West Region Agronomists:
Brian Whitlark, regional director, West Region – bwhitlark@usga.org
Ross Niewola, agronomist – rniewola@usga.org
Heather Schapals, agronomist – hschapals@usga.org