The impact of drying waterways on Northern California

Every year, Little Chico Creek goes nearly bone dry by the time autumn finally arrives, however, this year it had some longevity restored by the recent stormy winter.

CHICO — Every year, Little Chico Creek goes nearly bone dry by the time autumn finally arrives, however, this year it had some longevity restored by the recent stormy winter.

This is the same for many waterways throughout the north valley, like the Miocene Canal that, outside of the occasional boost from rainfall, has sat dormant since the Camp Fire. This creates enough inconsistency to make it difficult for ecosystems to take hold. Even with waterways that stay relatively continuous like Big Chico Creek and Butte Creek, years of dry weather can have an impact.

“It’s not good, just because the riparian ecosystems, the plants, the trees, if you have too many dry years, they can be negatively impacted,” said Chico State Associate Professor of Geological and Environmental Sciences Todd Greene. “They are adaptable, but if you have too many dry years in a row, it’s going to be a big stress on the local trees. That’s also why you’re not going to see fish. You’re not going to see healthy ecosystems because of that.”

Greene said Little Chico Creek doesn’t have the same level of drainage the larger creeks do, creating additional strains on its recharge rate in terms of inflow.

“A couple of wet seasons might extend the time for Little Chico Creek to have water, but its typical state is to go dry every year,” Greene said. “Just because it’s an intermittent or seasonal creek. It’s going to have that characteristic of drying out and that’s why you’re not going to have an established ecosystem of things living in it like fish or invertebrates. It’s going to look different from Big Chico Creek.”

In addition to local ecosystems, creeks, rivers and canals play a role in providing additional groundwater by seeping into aquafers. Butte County Water and Resource Conservation Director Christina Buck said waterways feed into the groundwater supply, helping in the recharge process.

“When we think about recharge and how water gets into the groundwater system, there’s the main ways like direct rainfall, and the other way is rivers flowing over groundwater basins which soaks in and recharges it that way,” Buck said.

Buck’s department is responsible for a yearly groundwater report to the Butte County Board of Supervisors that provides information on water levels and outlooks on how water might be spent or how it has been spent in the most recent water year. According to the Vina Subbasin water plan, waterways contribute just short of a fifth of the recharge for the supply. Buck said rain is responsible for about 80% of the recharge while about 18% comes from the waterways. The remainder arrives from things like irrigation using surface water.

Like Greene, Buck noted how the rains have made an impact on local flora in contrast to the years leading up to it.

“Certainly native vegetation received a reprieve with the return of wetter conditions this year,” Buck said. “The last three years of drought and extremely low precipitation during that time placed noticeable stress on unirrigated native trees and plants.”

In March, California Gov. Gavin Newsom signed an executive order that effectively made it easier for agencies to divert water, once increased by storms and other weather-oriented events, by allowing them to bypass permit processes for the purpose of groundwater recharge. Because of what was determined to be a flood risk, Butte County was unlikely to see any direct benefit from the executive order.

“The Butte County Water Commission started talking about ways to take advantage of the opportunity so the commission drafted a letter and recommended that the Board of Supervisors send it to DWR,” Buck said.

The letter expresses the county’s desire to create a groundwater recharge action plan by Jan. 1, 2024 which will contain recommendations that could lead to increased groundwater recharge during the wet months.

“The plan will identify the target amount of recharge that can be achieved by Dec. 31, 2030,” the letter reads. “This effort will consist of compiling information and data from existing studies to outline the near-term opportunities for actionable recharge that benefit Butte County groundwater conditions.”

Additionally, the letter details a pilot project for 2024 that includes rainfall retention in agricultural lands, diversion of flows onto agricultural lands during imminent flood risk times and operations in local flood channels like the Lindo Channel.

The letter was signed by Supervisor Tod Kimmelshue and sent to the California Department of Water Resources in June.

Though 2023 has had a positive trend in excessive rainfall, Greene pushed the importance of keeping an eye on the water situation, adding that the drought is nowhere near over.