The South San Joaquin Irrigation District could prove critical to the South County’s ability to meet state mandates regarding groundwater management by annexing farmland to the north and providing more surface water to cities.

They are among possible groundwater solutions being explored as SSJID undertakes a water master plan study aimed at solidifying, protecting, and building on 109 years of the district securing senior pre-1914 water rights and developing them for the benefit of South County farmers and residents.

The groundwater basin covering the South County is not currently significantly out of whack with the pending mandate that would restrict the amount of water withdrawn by pumping to at least the same amount of water recharging it during a set 12-month period. In a nutshell, there needs to be a zero-sum change in groundwater levels at the completion of a reporting period.

Since the 1920s some groundwater basins in the southern part of the San Joaquin Valley have been over drafted so much that they have caused sections of land to sink by as much as 28 feet. The area immediately north of the SSJID is experiencing serious groundwater over drafting.

That could be addressed by having farmland close to the SSJID — north of French Camp Road in the Manteca area — annexed to the district so they can obtain surface water and reduce or eliminate reliance on groundwater.

And while generally the conversion of an acre of irrigated farmland into urban uses typically results in roughly the same water being used, the continued drilling of new urban wells would mean in dry years that in order to maintain a balance as required by state law, water used for homes and other city purposes would have to be cutback significantly.

In order to serve existing development and farms and make sure there is adequate water for future needs the SSJID needs to have a comprehensive game plan that involves striking a balance with ground pumping using surface water, work to make sure endangered fish will flourish, improve water conservation, leverage expensive improvements needed to sustain water service by selling water out-of-district when feasible, and defend its water rights from regulatory challenges.

The plan will address threats that the district is facing from regulatory changes and legal challenges that ultimately could undermine long-established, legally adjudicated, and developed water rights on the Stanislaus River Basin that would cripple both farming and urban growth within the district’s boundaries. It will also provide direction for capital investment, operations and maintenance and modernization.

It would provide a plan for a 20-year horizon that would:

uprotect water rights.

uincrease the conservation of water.

uimprove the district’s resiliency to drought.

uaddress complying with regulations.

umake sure the district continued to be good stewards of the watershed.

The district over the years has astutely conducted research, made major investments, and adopted strategies that they have consistently followed allowing them to successfully defeat efforts to commander water with court victories. An example is the $1 million a year fish research the SSJID conducts with the Oakdale Irrigation District that provided scientific information to successfully counter state assumptions that releasing more water into the Stanislaus River would increase populations of endangered salmon. Being armed with data regarding the impacts of non-native predators and the time of water releases being significantly more effective than volume, has allowed the SSJID to prevail twice in federal court against the state contentions that were not backed up with any research data that more water equals more fish.

The two biggest challenges facing the district are a proposed state regulatory move to commandeer more water from three rivers — including the Stanislaus — in a bid to pump up Chinook salmon numbers. The other is the groundwater mandate.

A push by the state that would essentially grab water that the courts have adjudicated as belonging to SSJID and the Oakdale Irrigation District in a bid to get what state experts concede would be a net annual gain of  just 1,100 salmon/steelhead   combined on the Stanislaus, Merced, and Tuolumne rivers would mean:  

uThe potential of not being able to farm 132,000 acres now irrigated in the Northern San Joaquin Valley.

u120,000 acre feet of water SSJID and OID customers including the cities of Manteca, Tracy, and Lathrop could forfeit in a normal year with significantly larger cutbacks during drought years.

uIncreased groundwater pumping of 1.57 million acre feet of water annually by cities and farmers that would run afoul with the state’s mandated against over drafting water basins.

uAn annual economic loss of $12.9 billion to the combined economy of San Joaquin, Stanislaus, and Merced counties.

uSome $10 million OID and SSJID would lose annually from hydroelectric generation.

uThe loss of 4,000 jobs in the region.

uBased on historic hydrology on the Stanislaus River Basin, New Melones Reservoir — the state’s fourth largest at 2.4 million acre feet of water — could go dry 12 times every 95 years.

To contact Dennis Wyatt, email dwyatt@mantecabulletin.com