There is more water flowing these days in the Stanislaus River.
It is not due to increased agricultural water deliveries, urban uses, or for recreational purposes. The increased flows from New Melones Reservoir that have been ramped up to 350 cubic feet per second are designed to lower water temperature and pump up dissolved oxygen to create a less lethal environment for fish.
South San Joaquin Irrigation District General Manager Peter Rietkerk noted the Bureau of Reclamation’s increased releases from New Melones aren’t impacting water supplies for urban or ag use within the district nor farm deliveries in the Oakdale Irrigation District. None of the water being released is coming from OID or SSJID accounts.
That said, the SSJID is keeping a close watch on El Nina modeling — the name given conditions in and over the Pacific Ocean that typically deliver drier than normal weather patterns after an El Nino that tend to bring wetter winters. Neither weather condition is a 100 percent certainty that it will bring significantly more precipitation such as El Nino or significantly less such as La Nina. Over the long haul the two patterns associated with water temperatures and trade winds tend to deliver more extreme wet or dry weather.
“It (El Nina) looks like it may be weaker than originally projected,” Rietkerk said of modeling.
The National Oceanic and Atmospheric Administration is reporting that models have slightly backed off their confidence of 75 percent that La Nina will occur this fall and winter to 55 to 60 percent. That’s because trade winds have not shown the El Nina-like strengthen needed even though tropical waters in the Pacific have cooled. The NOAA notes “the current outlook favors a weak event, but remember: impacts aren’t always tied to event strength.”
New Melones at
24 percent capacity
At any rate, the SSJID is not counting on normal rain and snow on the Stanislaus River watershed in the weather year that starts Oct. 1 and is planning accordingly.
Models indicate there is a strong chance that California will be in a fifth year of drought. The above average snow and rain of the past winter and early spring helped ease the droughty but did not end it.
As of Sunday New Melones Reservoir was at 582,745 acre feet of water or 24.2 percent of its 2.4 million acre foot capacity. It is at the second lowest capacity of the state’s eight biggest reservoirs.
The only way to increase dissolved oxygen in water to make sure it is adequate for fish to breathe is to increase water flow. At the same time the spate of 100-degree plus days during the ongoing heat wave was raising temperature levels toward the point they could become lethal for fish.
The temporarily ramped up flows helps both issues.
The SSJID and OID spend $1 million a year on fish research on the Stanislaus River to provide scientific data they in turn use to help boost the population of endangered Chinook salmon. Both agencies operate on the principle they must be “good stewards” of the Stanislaus River to assure there is adequate water for fish as well as urban and farm uses. That philosophy in part is aimed at making sure situations don’t deteriorate and actually improve to prevent any additional federal and state regulations that could imperil water deliveries.
Normally the dissolved oxygen level needs to be at least 7 milligrams per liter on the Stanislaus River when it passes through Ripon. The Bureau allowed it last year to drop to 5 milligrams per liter in November due to the drought and the lack of storage at New Melones.
Environmental groups have decried dissolved oxygen levels below 6 milligrams as being reckless in that it is at levies that could thwart migrations since it makes fish less effective swimmers.
Stockton East Water District last year argued the 7 milligram standard for dissolved oxygen at Ripon was “contrary to the best available science.” The district argues cold water fish are substantially farther upstream during the summer heat.
Historically, dissolved oxygen levels and oxygen on the San Joaquin River at Vernalis near the confluence with the Stanislaus River south of Manteca and west of Ripon has also put added pressure on the Stanislaus watershed due to court orders and operating policies of the Bureau.