Merced Mysteries & Minutiae: Preventing flooding, capturing stormwater a balancing act

More than a month ago, the Merced Sun-Star published a letter to the editor that asked questions about some creeks and basins near Highway 99.

The letter referred to Owens Creek, Mariposa Creek, Deadman’s Creek and Duck Slough in the Plainsburg area. It was early February after many heavy January storms, but the basins near the highway were empty. Even so, the letter writer noted, water from the creeks flowed under the highway and eventually out to sea.

The letter writer asked many questions, which caught my eye.

Q: Don’t you suppose someone would have enough common sense to direct a portion of that runoff into these huge basins to recharge the groundwater? Who’s in charge?

A: Though multiple agencies manage the creeks, they are all heavily protected by the California Department of Fish and Wildlife.

The creeks are storm-event creeks, for the most part, said John Sweigard, general manager for the Merced Irrigation District.

“MID does use those natural waterways for management of our water system, but we don’t really have any control over water during storm-event season in those creeks,” Sweigard said.

The creeks’ main purpose, Sweigard said, is to get stormwater out of the area to prevent flooding.

Mike Walejko, an administrative engineer with Merced County, said the creeks are all naturally flowing. Fish and Wildlife monitors fish flow in the creeks and creates strict guidelines even when the county does creek clearing.

Each of those creeks flows into the San Joaquin River, Walejko said. So yes, the water from those creeks does eventually flow out to the ocean through the Sacramento-San Joaquin Delta.

A few of the creeks actually do have reservoirs in Mariposa County, but those reservoirs also are for flood-control purposes, Walejko said.

There’s a reservoir on Owens Creek that holds 3,500 acre-feet of water. A fixed outlet allows 2,000 cubic feet per second down the waterway. There also is a dam on Mariposa Creek.

“So there is some recharge up there,” Walejko said. “In the wet season, that actually does happen. But it can’t hold water like a reservoir. It has to be released.”

After years of punishing drought, Californians everywhere are defensive about wasted water.

“It’s just not so simple,” Walejko said. “It makes sense that when we see water flowing out, it’s frustrating. We’d like to capture that.”

There are various recharge or reservoir projects the county would like to get going, but they all cost money.

MID does have two groundwater recharge basins – one in the El Nido area and one in the Ballico-Cressey area.

In a typical year, MID helps recharge about 100,000 acre-feet of groundwater.

As for the basins near the highway, the California Department of Transportation manages those. Those also are meant to prevent flooding.

“We have no say on the basins,” Sweigard said.

Water in state Department of Transportation basins, such as the one on Highway 99 near Arboleda Drive, either evaporates or recharges the aquifer.

This story was originally published March 13, 2016 at 4:25 PM with the headline "Merced Mysteries & Minutiae: Preventing flooding, capturing stormwater a balancing act."