The Eel River came close to reaching its lowest recorded flow reading near Scotia on Tuesday but is not expected to reach it any time this week due to Wednesday’s rainfall.
On Monday and Tuesday, pressure flow gauges near Scotia recorded an average flow of 19 cubic-feet per second (cfs), just above the historic low of 18 cfs set more than 90 years ago in 1924, according to the U.S. Geological Survey.
However, surveys conducted by the Eel River Recovery Project at the site earlier this month found that the river was flowing at a higher rate of around 35 cubic-feet per second. But with four years worth of drought stacked against the river and a fifth year expected to begin at the end of this month, local researchers see any low flows as a cause for concern for local wildlife.
“This type of flow was expected,” fisheries biologist Patrick Higgins of the Eel River Recovery Project said. “There is some indications that it’s not just driven by lack of rainfall.”
While the river’s surface flows aren’t going completely dry as they had done a year ago near Fortuna, local researchers are more concerned about the state of the tributaries than the main stems of the water body.
National Marine Fisheries Service fish biologist Zane Ruddy said the low flows at sites like Scotia are general indicators of the health of smaller tributaries that flow into the main stem.
These sites are also where juvenile coho and steelhead trout listed under the federal Endangered Species Act are currently rearing. Due to a lack of monitoring on these tributaries, Ruddy said that they won’t know the extent of the impacts on these young fish.
“It’s hard to know exactly what the impact will be, but it’s certainly negative,” he said. “There is nothing good that can come out of it.”
California Department of Fish & Wildlife Southern Humboldt and Mendocino Counties Senior Fisheries Supervisor Allan Renger said that low-flowing waters and sediment buildup from human and natural reduces the overall quality and quantity of available habitat for these fish as they grow.
“There is going to be a reduction in juvenile production for the Eel River basin,” he said.
The river is expected to get a slight boost from Wednesday’s rainfall, but it will be short-lived, National Weather Service senior hydrologist Reginald Kennedy said. After this “quick shot of rain,” Kennedy said it’s back to dry weather until next week.
The precipitation is forecasted to provide a brief pulse on the river that would nearly double the flow to a peak of 81 cubic-feet per second on Friday, according to the National Atmospheric and Oceanic Administration’s California-Nevada River Forecast Center. However by the end of Saturday afternoon, flows are predicted to drop down to about 30 cubic-feet per second. While another quick bout of rain is expected on Sept. 21, Kennedy said the rest of that week has a dry forecast.
Exactly a year ago from Tuesday, flows on the Eel River were running at an average of 36 cubic-feet per second, but this was aided by increased flows provided by Pacific Gas and Electric Co. through its dam on Lake Pillsbury from mid-August through October 2014.
Unlike last year, Ruddy said the lake has a much more depleted reservoir and was not able to be called upon to increase flows this year. Nature also lent a hand to the Eel River last year with a surge of rain at the end of September 2014, ramping up flows up to an average of 187 cubic-feet per second, according to the U.S. Geological Survey.
Despite having a wetter winter season during this water year — which began in October 2014 and ends on Sept. 30, 2015 — than in the previous 2013-2014 water year, Higgins said the dry spring and the compounding effects of drought are taking their toll on the river.
“It’s been dry for so long, we’re almost getting the same resulting flow (as 2014) even though we got more rainfall,” he said.
Other sections on the South Fork Eel River such as Miranda and Leggett also approached record low levels as of Sunday, according to U.S. Geological Survey data.
Low rainfall and low flows are historically common for the North Coast as September nears its end. As the rain picks up in the fall and winter months, it also triggers the upriver migration of the fall and winter runs of adult steelhead trout and Chinook and Coho salmon.
The first arrivals are the Chinook salmon, which are currently holding in pools within the Eel River Estuary and typically move to their spawning grounds upriver around mid-November. But that’s only if enough rains come, Renger said.
As rains increase river flows, the fish are triggered to begin moving as close to their tributary spawning grounds as they can until stopped by patches of low water. Renger said should a significant amount of rain not fall, the fish won’t move.
“So if there are two weeks in December when it doesn’t rain, that moves a particular migration back three weeks,” Renger said. “They just hold in the river until we have the water flow conditions that move them.”
Ruddy said if salmon are not able to make it to tributaries, they can end up holding in large groups on the main stem of the river, which tends to be warmer the farther upstream you go. Similar to salmon on the Klamath River, these conditions make the fish more susceptible to diseases as well as poaching.
“You don’t want a bunch of fish in one place,” he said.
Article by: Will Houston
Published by: Eureka Times Standard
Published date: September 16, 2015
Read article online at Times Standard
Friends of the Eel River’s response to this article:
By: David Keller, Friends of the Eel River Bay Area Director
Low rainfall, low snowfall, hot and dry conditions are once again proving very damaging to the Eel River’s water quality and upcoming Chinook in-migration.
An important fact was completely missed in this article: For the past 4 months, more Eel River headwaters’ flow has been diverted by PG&E at its Potter Valley Project hydropower plant into the Russian River’s East Branch, than is being released into the main stem Eel River downstream of PG&E’s Cape Horn dam.
As a result, Lake Mendocino (primarily benefiting the Sonoma County Water Agency’s customers) and the Potter Valley Irrigation District and other Russian River-dependent growers receive more Eel River water than does the Eel River, when it is most needed for Eel River fish flows, with cool and clean water.
This fundamental tragedy must be corrected soon, through the Federal Energy Regulatory Commission’s relicensing process coming up for PG&E.
The mighty Eel can be restored to her historic greatness, for the benefit of the Eel River watershed and fisheries, but the current beneficiaries of free water transfers into the Russian River basin will have to learn how to change their practices.