Arroyo Grande will likely put a halt to new building in the city if one of its main sources of water — Lopez Lake — keeps declining.
The Arroyo Grande City Council approved a new set of “triggers” for water shortage emergencies Tuesday night that would kick off a building moratorium and require residents to conserve 5 percent more water than they are already conserving, if water levels at Lopez Lake keep falling.
Fortunately, that isn’t expected to happen immediately.
The restrictions would be triggered in one of three situations: if local water deliveries are interrupted in some way (such as if the treatment plant suddenly fails); if there is a significant threat to water levels in the Santa Maria Groundwater Basin (Arroyo Grande’s other source of water); or if Lopez Lake holds less than 10,000 acre-feet of water — about 20 percent of its total capacity.
Fully filled, the reservoir can hold an estimated 49,388 acre-feet. One acre-foot of water is equal to 325,851 gallons, or generally enough to supply three households for a year.
10,000 If Lopez Lake water levels fall below 10,000 acre feet, the new water restrictions would be instated.
As of Wednesday, Lopez Lake was 20.5 percent full, according to data on the San Luis Obispo County Water Resources website, with 10,114.5 acre-feet of water. That means the city was about 114.5 acre-feet away from reaching the triggers the council approved Tuesday night.
There is some discrepancy in how much water could be in the lake, however. On Tuesday night, city staff said the reservoir held between 11,000 and 11,500 acre-feet, making the restrictions trigger slightly further away. Staff said they were unsure about the discrepancy in data, though it could be due to stored state and carry-over water the city does not have rights to.
325,851 How much gallons are in one acre foot of water.
The moratorium would prohibit adding new water connections in the city, unless the project has already been approved by the city at the time the trigger is reached.
It does have some exceptions, namely for projects that agree to participate in the city’s water offset program, which requires them to show water savings through the payment of fees, the purchase of new permanent water supply and/or extra conservation measures.
The city has been in a declared phase 1 water shortage emergency since May 2015. Under that emergency, all city residents were required to reduce their water consumption by a certain percentage depending on historic water use, or face fines.