180/400-Foot Aquifer GSP Update – Comments on Chapters 5-6 re Groundwater Conditions and Water Budget
John Farrow
Dear Members of the 180/400-Foot Aquifer Subbasin Committee:
Attached are comments made on behalf of LandWatch Monterey County regarding Chapters 5 and 6 of the 2022 180/400-Foot Aquifer GSP Update. Chapter 5 describes groundwater conditions and Chapter 6 provides historical and future water budgets.
SUMMARY OF COMMENTS:
The water budget chapter purports to provide the historical water
budget in Table 6-8 based on the Salinas Valley Integrated
Hydrologic Model (SVIHM) and to provide the future water budget in
Table 6-13 based on the Salinas Valley Operational Model (SVOM).
However, the water budget chapter rejects the modeled results for
critical parameters, including groundwater pumping, seawater
intrusion, and storage loss, and substitutes “adjusted” figures
instead. It remains unclear how the calibration of the model’s
other parameters could possibly remain valid after these
adjustments. The bottom line results for loss of storage in Tables
6-8 and 6-13 based on these adjusted values are simply
inconsistent with the other values in these tables. The tables do
not add up; and the water balances are not balanced.
Furthermore, Chapter 6 ultimately does not even use its modeled
results to determine either historic or future sustainable yields.
All of the values used in determining sustainable yields are based
on estimates made outside of the modeling process. In effect, the
modeled results are meaningless.
Finally, Chapter 6 fails to provide a clear statement of the overdraft condition. SGMA requires that the water budget provide a clear statement of the magnitude of the overdraft. (23 CCR, § 354.18(b)(5).) The overdraft figure must be clearly stated because SGMA requires that the GSP include a “quantification of demand reduction or other methods for the mitigation of overdraft.” (23 CCR, § 354.44(b)(2).) Chapter 6 repeatedly implies that the overdraft is only 600 AFY. This implication is inconsistent with the estimate in Chapter 5 that the overdraft includes both that 600 AFY storage loss that is estimated based on groundwater elevation changes south of the seawater intruded area and an additional 12,600 AFY storage loss that is estimated based on the average annual volumes of seawater intrusion. The water budget must include this total overdraft, as defined by Bulletin 118.
The attached letter further details these comments.
Thank you for your consideration,
John H. Farrow
M. R. Wolfe &
Associates, P.C. | Attorneys
Land Use | Environmental Law | Elections
415.369.9400 | Fax: 415.369.9405 | www.mrwolfeassociates..com