City of San Luis Obispo CA : Spring is Mowing Time at Whale Rock Reservior
Everyone who has a lawn knows that it takes work to mow and maintain. The same is true for people who have larger properties and must perform seasonal weed abatement to maintain defensible space and reduce fire hazards.
At Whale Rock Reservoir, we have approximately 7 acres of steep dam face that requires weed abatement on an annual basis. Most people cannot imagine mowing 7 acres and Whale Rock staff could never accomplish this without heavy equipment. Whale Rock staff uses a John Deer tractor and flail mower, which allows staff to mow the dam face area in approximately 24 working hours.
The Division of Safety of Dams (the certification agency for dams) requests that our dam face is mowed annually. The reason for mowing is not aesthetics, but relates to the safety and long term viability of the dam structure. There have been negative impacts when ground squirrels have perforated the earthen structures, allowing water to flow thru the rodent holes and erode the physical structures that keep water in levees or behind dams. When the dam face is mowed, birds of prey are able to reduce the rodent population through predation. The most common alternative to natural predation is poison ground squirrel bait. Staff feels that allowing nature to reduce rodent populations is sustainable, reduces the chance of non-targeted animals being effected, and causes no adverse effects on the environment.
Whale Rock staff has become skilled at operating the mower on the steep inclines of the dam face and look forward to the annual mowing season. The images depict Water Supply Operator, Ed Humphrey, nearing the end of the 2017 dam mow.