Category Archives: Uncategorized

By Kat Perkins

Nimbus Basin on a sunny October day.

Over the past year, I’ve spent almost 1,000 hours looking at aerial photos of the lower American River, counting redds. In addition to staring at these gorgeous aerial photos to map spawning, I have been taking a closer look at the method we use to make redd counts. With the help of folks at Cramer Fish Sciences, I was able to get a better picture of how repeatable aerial redd counts are and how we can improve the accuracy of our counts. It turns out that the process is almost as much an art as a science: the decision to count a feature as a redd is subjective, and the more familiar you are with the river the more likely you are to make good decisions.

One recommendation to improve accuracy that came out of this research was that the technician performing counts should visit the river to monitor spawning on the ground. Since I’ll be doing counts again this year, that means I get to visit the river, search for salmon, fly a drone and call it work! After looking at the river in two dimensions for so long, it’s really exciting when I get to actually experience it.

This past Sunday, I met Bureau of Reclamation scientist John Hannon at Nimbus Basin to monitor early spawning. I found John at the edge of the parking lot. “There’s a lot of fish out there!” he said. Looking out I could see fish jumping out of the water. But were they spawning yet? Probably not, since it’s only mid-October and water temperatures at the dam release have just recently been hovering around 62 degrees, but we’d have to look a little closer on foot and with the drone to know for sure. John grabbed the drone out of his car and then we made our way down to the water.

When we got to the side channel, John asked if I minded getting my feet wet. “No!” I answered enthusiastically, and we waded into the water. I pointed down the side channel to where there had been rocks piled to make a dry crossing and explained that I’d spent most of Friday moving these rocks. John was happy to know that, since he’d noticed that the walkway was blocking the side channel off for fish and had pointed this out to Lilly who’d sent me out to the river. While pretending to be a human bulldozer (just call me Katerpillar) I watched a fish swimming through the deeper part of the side channel and wished I had the salmon equivalent of traffic signage to let my new friend know the road would soon be clear for fish passage.

At least one “slam-dunk”, totally unmistakable redd is visible in this photo, at the upper end of the side channel.

Upstream from where John and I crossed through the side channel, we could see a redd through the water. In aerial photos, redds show up like white polka dots against the dark river bed. On the ground, the light rocks the salmon uncover while building their nests almost glow through the water and you can see the “pot” of the nest the salmon has excavated. When we got to the edge of the last little island in the basin, we saw one more redd and a fish guarding it. We could also see that there were two fishermen, and on the other side of the basin, a Fish and Game officer.

This year, Nimbus Basin is closed to fishing. This was bad news for these two fellows, but good news for fish and, in the longer term, fisherfolk. The Hatchery plans to reorient its fish ladder into the Nimbus Basin and remove the weir, and that’ll open more prime spawning and rearing habitat to fish. Fewer people in the basin also means that we can more safely fly our drone to monitor spawning.

There are already a lot of fish in Nimbus Basin, visible in this drone photo as dark spots.

From an open spot on the other end of the basin, John launched the drone and flew a grid across the basin. We could see lots of little of black ovals – fish! But not many redds. After checking Nimbus, we visited Sailor Bar and Sunrise.

John flew the drone again at both Sailor and Sunrise. Usually John would just bike along the Parkway bike path and look out for fish but this year he’d promised photos of any early redds to a researcher at NOAA, who is investigating the effectiveness of redd monitoring using a drone. He had planned to conduct his research on upper tributaries to the Sacramento, but because of worries about how the fires would impact water quality the study site was relocated. The circumstances are tragic, but it is exciting for us to have more eyes on the American, and to participate in more cross-agency collaboration and learning.

John catches the “bird” mid-air after flying Sunrise.

John has been visiting the river to monitor the beginning of fall run Chinook salmon for many years. Knowing how the run is progressing helps him make decisions about scheduling the flights to capture aerial photographs of the whole river. We’ve been using these aerial photos to perform redd counts since 1991, and this relatively long-term data set is an incredible resource.

This is only my second year witnessing the salmon return, but I can’t imagine that this season becomes any less exciting the more times you’ve experienced it. In fact, the more I know about our river system, the more interesting it is. There are so many factors that converge to make the run what it is, so every year is unique – yet, we can also pick out patterns, and understand how to better manage and monitor.

ARG Temperature Shutter Change

Posted on Thursday, October 4th, 2018


The following Folsom Dam Temperature Shutter Change Order was issued by Peggy Manza on 10/3/2018:

This is to document that Unit 3 was put  in configuration 4 at approx 10 am on Thursday September 27, 2018.

Configuration after changes:


Upper shutters – Units 1, 2, and 3 up

Middle shutters –  Units 1, 2, and 3 up

Lower shutters – Units 1 and 3 up, Unit 2 down


Comment: Temperature management in the Lower American River

Change Order

Posted on Friday, August 17th, 2018

Temperature Shutter Change

The following Folsom Dam Temperature Shutter Change Order was issued by Peggy Manza on 8/17/18:

  • Please put Unit 1 in configuration 3 at approx 7:30 am on Monday, August 20, 2018.

Configuration after changes:


Upper shutters – Units 1, 2, and 3 up

Middle shutters –  Unit 1 up, Units 2 and 3 down

Lower shutters – all down


Comment: Temperature management in the Lower American River

Ordered by:  Peggy Manza


Flow Change

The following change order was issued by Peggy Manza on 8/17/18:

Please make the following release changes to the American River at Nimbus:

Date         Time    From (cfs)      To (cfs)

8/21/18       2100      3,100            3,000

8/21/18       2200      3,000            2,900

8/21/18       2300      2,900            2,800


8/22/18       2100      2,800            2,700

8/22/18       2200      2,700            2,600

8/22/18       2300      2,600            2,500


8/23/18       2100      2,500            2,400

8/23/18       2200      2,400            2,300

8/23/18       2300      2,300            2,200


Comment:  Reduced delta needs

New residents at Cordova Creek

Posted on Thursday, August 2nd, 2018

New Residents at Cordova Creek

Overview of Cordova Creek in July 2018

If you have recently strolled through Cordova Creek, you may (or maybe not) have noticed new additions to the creek – beaver dams! On the one hand, this is an exciting indicator of the successful naturalization of the area, as native species continue to utilize the site and make it their home! Though beavers provide numerous ecological benefits –like increasing biodiversity, preventing downstream flooding, and minimizing pollutants – they can also simultaneously cause problems in urban environments, commonly referred to as human-wildlife conflict.

Our CivicSpark Fellow Cassie has worked diligently to find a solution to balance the needs of the beaver with the successful establishment of the creek.

Left: Beaver dam creating a pond ecosystem Right: The pond leveler installed and managing pond dimensions

As the ubiquitous population of North American beavers (Castor canadensis) has steadily recovered from historic depletion, it has become increasingly apparent that these aquatic mammals can fundamentally modify existing hydrologic regimes. Due to this ability to change their environment, beavers have earned the status and nickname of ecosystem engineers. In natural environments, their engineering abilities can be incredibly beneficial.

However, the initial dam on Cordova Creek had detrimental impacts on the newly naturalized site. The beaver dam caused nearby banks to submerge, which in turn caused the drowning of young plants and it began to overflow across the trail. Additionally, the beaver removed cottonwood trees, young willows, and many yards of irrigation which cascaded into many more plant problems.

Though the damage caused by the beaver was not easy to ignore, we recognized that it would be unreasonable to get mad at a beaver for simply doing what beavers do. Thus, we brainstormed ways to live peacefully with the beaver, while continuing to maintain the site in its early years of establishment. Through the help of Sacramento-Yolo Mosquito & Vector Control District, a pond leveler was installed on the creek. The pond leveler is a pipe that goes through the dam to allow a certain amount of water to pass through the dam whilst maintaining a pond environment for the beaver.

Additionally, through the help of Soil Born Farms, their summer high school interns spent a morning on Cordova Creek assisting in wrapping vulnerable cottonwood trees with fencing to protect the trees from beaver herbivory. Cottonwood trees have slower growth rates compared to willows which will naturally recover faster from beaver herbivory. Now that the cottonwoods will have a chance to grow, they will be able to provide some shade to the many walkers, runners, and cyclists enjoying the trail.

Left: Student interns prepare to wrap a cottonwood tree Right: Student interns pose and smile after wrapping 15 cottonwood trees

As Cordova Creek continues to establish itself, we look forward to welcoming new wildlife residents to the neighborhood and finding innovative ways to resolve any more human-wildlife conflicts that may arise.

Managing Cordova Creek: Staying ahead of Star Thistle

A native to Mediterranean Europe, the yellow star thistle (Centaurea solstitialis) made its way to California during the mid-19th century, likely via Chile through contaminated alfalfa mixes. With the lack of natural herbivores, the star thistle has the ability to create monotypic stands along disturbed landscapes. Their voracious nature eliminates and prevents other plants from growing, which degrades ecosystems and acts as a physical barrier for animal and human movement in wild spaces. Currently, it is estimated that star thistle occupies over 15 million acres of California’s floristic zone, and Cordova Creek, along with the American River Parkway, is no exception.

An unseasonably wet winter ‘16-17, hot summer, and the recently disturbed soil from Cordova Creek’s construction, all aligned to create an ideal habitat for star thistle to thrive in. As a result, the population exploded to an unprecedented level that the Water Forum and our partners were unprepared to fully manage. However, we are using the knowledge that we learned from last year’s experience to guide our current management strategies.

Starting in April, work crews have diligently hand-pulled and removed thousands of young star thistle growing throughout Cordova Creek. Despite their hard work, star thistle persistently exists in a few problem areas. To help address these problem areas, the Cordova Recreation & Park District,  Soil Born Farms, and the American River Flood Control District kindly agreed to each donate a day of mowing at Cordova Creek. Mowing star thistle can be extremely effective as a removal technique if timed correctly – once the plants have matured, bolted, and are at ~10% flowering. Mowing during this critical period prevents seeds from developing, and, without rain, the plants will be unable to regrow and flower this season.

We appreciate the help of Cordova Parks and Recreation, Soil Born Farms, and the American River Flood Control District as we manage and control star thistle. We are confident that the combined efforts will ensure the success of Cordova Creek and the immense amount of ecosystem services that it provides to the community!

For more information on how to manage star thistle in your own area: Yellow Star Thistle Management Guide