The next pressing water problem facing the Stanislaus River watershed is the potential for too much water flowing in the coming months when fish spawn.
The National Marine Fisheries Service is seeking the South San Joaquin Irrigation District’s help to divert water off the Stanislaus River to reduce peak flows in December. That’s when steelhead and salmon spawn.
The danger is that when female fish create “redds” or depressions in small areas of gravel to form egg pockets they need to find relatively calm water. That means spawning at higher elevations in the river channel at peak releases. It could end up stranding salmon fingerlings when flows drop creating the potential for the fish population to take a hit. That is something the SSJID, Oakdale Irrigation District as well as federal and state agencies don’t want to see happen.
Reducing water flows in the Stanislaus River during the spawning period is an objective of the Bureau of Reclamation as well.
However, that conflicts with an Army Corps mandate that New Melones storage be down to 1,970,000 acre feet or lower by Nov. 1 as part of a crucial flood control management plan. Based on current inflows and outflows New Melones will not meet that mark on Nov. 1. The 2.4-million acre foot reservoir as of Monday had 2,017,320 acre feet of water or 150 percent of normal for Oct. 23. Typically there is only 1.3 million acre feet of water in New Melones this time of year.
That means higher-than-normal flows will be needed during the fall period when spawning takes place to provide required flood control space.
In the past, the SSJID when called on to help has been able to do so by diverting water to the McHenry Spill south of Escalon as well as other downstream spillways. This year, however, due to work on the McHenry Avenue Bridge, the district’s ability to use those spillways is severely limited and can only be used for storm water.
SSJID General Manager Peter Rietkerk in a memo to the district board noted because of the bridge work it is preventing a significant bypass flow capacity for the district’s distribution system.
Rietkerk notes the district could assist by rising Woodward Reservoir to a maximum elevation of 205 feet and bypassing some flows farther upstream. He noted, however, that may not be significantly enough to provide “the level of assistance that (the Bureau of) Reclamation may be requiring is precipitation is heavy this winter.”
The board at today’s meeting is scheduled to discuss fall operations for the SSJID system but isn’t expected to take any action.
Depending upon how the weather unfolds this fall and winter, one scenario that could hurt urban and agricultural water users that might emerge is for the fish population to be hit hard with fingerlings stranded and then for a drop off later in the winter that sends perception below normal. A drop in fish numbers in the past has prompted state and federal agencies to push for more water releases specifically for fish in the spring.
If the fish population ends up being hit hard and drought conditions or below precipitation years return in the next few years it could pose an issue when it comes to delivering water commitments. That may not occur but it is a scenario that SSJID and OID would like to avoid if possible as they have a vested interest in keeping the fish numbers high on the Stanislaus River.
It is why they have invested millions to create spawning areas and to monitor fish movements over the past 10 years.
The SSJID board meets at 9 a.m. today at the district office, 11001 East Highway 120, Manteca.