A North County community activist says that a decision by mayors, county supervisors and water district reps about desalination was made at a hastily called meeting and did not take adequate notice of crucial issues including potential salt water intrusion and impact on wells. -DB
Monterey Herald
Guest commentary
June 2, 2009
By Ed Mitchell
North County community activists have dedicated years to be included in a regional water solution because we have neighbors without water, wells going dry, and families drinking from wells increasingly polluted with nitrate or arsenic.
So, I and others were stunned when we learned of the water desalination decisions made at a hastily called “special meeting” on March 23. It was composed of two supervisors and the mayors of Seaside, Sand City, Del Rey Oaks, Monterey, Pacific Grove; together with representatives from the Monterey Regional Water Pollution Control Agency (MRWPCA), the Monterey County Water Resource Agency (MCWRA), and the Marina Coast Water District (MCWD).
This group decided to allow more overdrafting of the Salinas Valley basin by extracting brackish water from the 120-foot aquifer west of Armstrong Ranch, just a few miles southeast of the Castroville Saltwater Intrusion Project that injects water into the same basin.
The extracted water, polluted by salt from the ocean, would then be desalinated at a publicly owned plant near the Marina landfill. Eighty-five percent of the resulting potable water would be shipped to the Peninsula and 15 percent would be retained in-basin.
This distribution ratio was based upon the claim that only 15 percent of the brackish water was composed of basin groundwater. A benefit of this plan is that overdrafting of the Carmel Valley River would be solved by the desalinated water flowing out of the Salinas Valley basin.
Amazingly, despite two-thirds of the invited attendees being water experts, such as the MCWRA’s general manager, no one exposed how much brackish water would be mined from the Salinas water basin, nor provided an engineering explanation of why such mining would not increase salt water intrusion, or would not impact up-gradient wells in Oak Hills, Royal Oaks, Prunedale, or the Granite Ridge area.
Answers to these three issues reveal grave weaknesses in this brokered solution.
According to the modeling report in the Cal Am Coastal Water Project environmental impact report, 2.2 gallons of brackish water must be processed to generate one gallon of potable water, leaving 1.2 gallons of salty brine water for discharge into the ocean.
Thus, to generate 10,000 acre-feet a year (AFY) of desalinated water requires mining 22,000 AFY year out of the basin. This is a huge amount of water removal counterproductive to the injection efforts in the Castroville area, and it simultaneously encourages marginal up-gradient wells to go dry.
Simply stated, the March 23 brackish water desalination decision solves the California jurisdictional requirement to stop overdrafting the Carmel River of 3,300 AFY by significantly overdrafting another basin by 22,000 AFY.
And what about the 85-15 transfer ratio and how much expense Peninsula folks should be expected to pay to receive the desalinated water?
Actually, one-third of each desalinated gallon is groundwater (15 percent of 2.2 gallons equals 0.33 gallons.) Unfortunately, none of the water experts surfaced this fact to attendees. Thus the true transfer rate should be 67-33. Therefore, only 6,700 AFY should flow to the Peninsula whose ratepayers there should only pay 67 percent of the expense, not 85 percent.
Additionally, the false 85-15 ratio transfers 1.800 AFY (3,300 minus 1,500) of Salinas Valley groundwater out of the basin, depriving coastal farmers and residents in Castroville, Moss Landing, and Prunedale from use of that potable water.
County residents will support a regional solution if it does not unfairly or harmfully take water from one overdrafted basin for another overdrafted basin.
The March 23 solution needs work to avoid leaving North County high and dry.
Ed Mitchell is active in North County land use issues as part of the Prunedale Neighbors Group.
Copyright 2009 Monterey County Herald