Weeds Fall Prey to High Water and Citizens

By Alan Crockett

This year, 2017, the big news regarding the Boise River is the high flow.  And while that’s challenging news for some homeowners and we who recreate on the Greenbelt; there’s good news too.  The most desirable trees along the Greenbelt are the native Cottonwoods and Willows; both can withstand the flooding.  In fact, flooding and a bare seedbed is just what Cottonwoods need for regeneration. This regeneration has been missing on the Boise River where flows are now controlled by dams and reservoirs.

It’s also good news because some noxious and obnoxious weeds may be set back or killed by prolonged inundation.  An example, the Russian Olive is an invasive tree that has been reported to be controlled by flooding.  We shall see since there are hundreds of small Russian Olive trees in Marianne Williams Park and they are under water.

WhitetopPretty But Noxious

One noxious weed that may be controlled is Whitetop (also known as Hoary Cress), now in flower along the Greenbelt.  Noxious weeds are non-native invasive plants declared as noxious by the government because of their potential economic damage.  Whitetop displaces native plant species and reduces biodiversity, wildlife habitat and forage production.  It is poisonous to cattle.  Herbicides are only marginally effective on Whitetop; also, the roots go down many feet making pulling ineffective on established plants.

According to a Montana University Report, flooding can be a useful method for controlling Whitetop. Apparently successful flooding to control Whitetop requires continuous submersion from May until September in most cases.  In our case, some of our whitetop will be flooded from March through June or longer.  We can hope it works, but the bare ground that will be left behind will be an open invitation to seeds of both desirable and undesirable plants.

Citizen Volunteers Combat Weeds

volunteersCitizen volunteers can play an important role in controlling invasive plants along the Boise River. While volunteers are limited in the controlling weeds on public land along the Greenbelt because we’re prohibited from using chainsaws or applying herbicides, we can help control some weeds by pulling or severing the taproot and preventing them from going to seed.  If the seeds are short lived in the soil, it should be possible to control some weeds in just a few years.  Poison Hemlock, Houndstongue, and Spotted Knapweed are three examples of noxious weeds found on the Greenbelt whose seeds survive for only about 3 years.

Other plants, including trees, can be controlled as seedlings, and plants like biennial thistles can easily be controlled by severing the taproot prior to blooming.  With a little knowledge of how to ID these plants and a knowledge of their growth characteristics, we should be able to make a significant difference in areas that have small populations of plants.

Control of Russian Olive and other established trees can be facilitated by public and private landowners by cutting the trees using chainsaws and immediately painting the stump with an appropriate herbicide.

Weed Warrior Orientation

Martha Brabec, Restoration Specialist for the City of Boise, is working on a plan to prioritize remediation efforts and provide information on plant identification and control methods.  She’s starting a program like Montgomery County’s Weed Warrior program. Participants will train on weed ID and removal with her in the field and in the classroom, and then are “certified” to complete tasks on their own. Weed warriors will log hours, weeds removed and locations using an on-line form, and will have monthly or bi-monthly group projects. I’d love to see you at the upcoming orientation.

Weed Warrior Orientation
May 31, 6:00 – 7:00 pm
Foothills Learning Center

Editor’s Note: Implementation of a comprehensive invasive and non-native weed control program is recommended in the Boise River Enhancement Plan. The cottonwood forest along the Boise River was historically vast and had an understory comprised of willow, alder, birch and rose; this has been compromised by a mix of non-native and invasive species, including false indigo (Amorpha fruticosa), several grasses, (e.g. reed canarygrass [Phalaris arundinacea]), poison hemlock (Conium maculatum), purple loosestrife (Lythrum salicaria), and various deciduous trees.  These species out-compete native plants and decrease the function and value of wetland and riparian habitat. The Boise River Enhancement Plan identifies the removal and management of these species as a priority action.


Science Proves Benefits of High Flows

by Rob Tiedemann, Ph.D.

    1. “What do we want . . . empirical science.  When do we want it . . . after peer review.”
        1. (April 22, 2017 Sign displayed at the March for Science, Boise, Idaho)

      By any objective measure employed by peer reviewed science – including species diversity, number of habitat types, and community structure – rivers and their forested floodplains provide greater quantity and quality of wildlife habitat as compared to reservoirs.  This is intuitive to most of us who recreate in the outdoors and interact with anglers, hunters, and naturalists.

      Periodic flood flows are needed to maintain the health of riparian habitat.  Among other public benefits, flood floodplainflows: (a) recharge the shallow groundwater aquifer which later releases water to down river wetlands, (b) sweep the channel free of debris and maintain the conveyance capacity of the river, (c) control noxious weeds by physical disturbance and prolonged inundation, and (d) establish a seedbed for black cottonwood, the dominant native tree species of the region.

bald eagle
Cottonwoods are intolerant of shade and require flood flow events to provide fresh alluvium within the channel, and scour of the adjacent floodplain to remove competing species that may shade young seedlings.  In unregulated rivers, this commonly happens only one in ten years, leading to the establishments of cohorts of cottonwoods in large, same age stands.  The resulting mosaic of blocks of cottonwoods of different sizes – seedlings, whips, immature, and mature trees – contributes to the diversity of habitat for wildlife, especially birds which include bald eagle, osprey, great blue heron, black capped chickadee and other song birds.

black-capped chickadee


The cottonwood forest is also essential for its contribution to the base of the food web, and is the principal source of nourishment for the aquatic ecosystem.  Each fall, the massive amount of leaf litter that falls to the ground flushes to the river and provides the carbon needed to fuel the ecosystem.  No other species contributes an equivalent amount of energy to feed the community of aquatic insects, that feed the fishes making the river their home.


downy woodpeckerLastly, the cottonwood forest lessens the impacts of urbanization by shading the river and moderating water temperatures to make the river habitable for cold water species like rainbow trout.  And, it sequesters nutrients, like phosphorous, which has been documented in the scientific literature to cause nuisance blooms of algae in the Lower Boise River.

The profits to the public resulting from the remaining free flowing portions of the Boise River and its tributaries are observable, measurable, and have been demonstrated repeatedly.  These three criteria are the foundation of science and distinguish it from speculation, casual observation, or self-serving interest.  Public policy will determine future management of the Boise River.  I value that which is based on information with origins in science.  It’s a good way to do business.

Rob Tiedemann, Ph.D.
Certified Professional Wetland Scientist – Society of Wetland Scientists No. 0000702
Certified Wetland Delineator – US Army Corps of Engineers April 15, 1994
Certified Fisheries Scientist – American Fisheries Society No. 1,717
Certified Wildlife Biologist – The Wildlife Society December 10, 1986
Certified NPDES BMP Designer – Idaho Transportation Department 1996

Photos: Boise River Floodplain by Community LLC

Bald Eagle, Black-capped Chickadee, and Downy Woodpecker by Ken Miracle

A Place for Floods to Go


Boise WaterShed River Campus Opens With a Splash

The City of Boise hosted a great party on April 12 to officially open the Boise WaterShed River Campus, a winning combination of public art and interactive environmental education.  The Boise River Enhancement Network congratulates the many dedicated staff, artists, volunteers, elected and appointed officials at City of Boise and Boise WaterShed Exhibits Inc. on a job well done.

ribbon cutting

Boise City Council President Elaine Clegg gets expert help cutting the ribbon

heron art

The Boise WaterShed has the largest collection of public art in Idaho.

Matt Gover

Artist Matt Grover. His metal sculpture is a graph of water flow in the Boise River.

Interactive exhibits abound.

Boise WaterShed Director Cindy Busche

Elaine Clegg, Doug Fowler and Dave Eberle

New River Campus Opens at Boise WaterShed

By Julie Scanlin and Cindy Busche


Boise WaterShed River Campus

Drip. Drop. Sploosh!

Like raindrops dropping one by one on pavement, gathering together and gaining momentum as they flow to the river, the creative ideas of artists, engineers, educators, landscapers and exhibit designers flow together to form a confluence on the new River Campus at the Boise WaterShed Environmental Education Center.

A public grand opening is scheduled for Saturday, April 15 from 10:00-1:00 – join us to see the “new” WaterShed and the largest collection of Public Art in the State of Idaho.

The 2-acre living display and the renovated interior exhibit hall transform the messages of conservation and protection in an experiential way. However, it’s how the story is told that makes this a unique cultural destination.

boy and girlThrough the interpretation of artists, and the lens of science, we tell the story of our watershed through public art in the River Campus. Visitors will experience water cascading from the headwaters, flowing into Lucky Peak Reservoir. They can manage the water flowing from Lucky Peak Dam and stroll past the City of Trees, through a facsimile of the water renewal facility, then follow the flow of the river, past wildlife, agricultural areas, and a wetland.


interactive water displayVisitors will have a better understanding of how their actions upstream impact the water availability and water quality downstream. Families and young visitors will enjoy the sewer pipe play area and learn the importance of a healthy ecosystem with nature play in the interactive trail. More than 179,000 people have experienced the Boise WaterShed’s programs since 2008. The renovated exhibit hall and upgraded exhibits now welcome them back and invite new experiences for young and old.

BREN’s  Boise River Enhancement Plan recognizes the critical role of education facilities and programs in engaging the public in the important work of taking care of the Boise River. Congratulations to City of Boise and the Boise WaterShed Exhibits Inc. for investing in the future of our river and our community.


exterior photo

Floodplains Are Refuge for Fish in High Water

by Michael K. Homza, PE

It’s humbling to stand on the banks of the Boise River as it roars by above its official flood discharge of high water Boise River7,200 cubic-feet-per-second (cfs). It’s deep, cold and fast. I wonder if I could survive an attempt to
swim across to the other bank. I shudder at the thought. Luckily, I don’t have to be in the river; but what about the fish? How do they survive this roiling rollercoaster? Aren’t they just swept away during high flows? Where do they go in high water? The short answer is simple: floodplains.

As Tamsen Binggeli mentioned in her March 6, 2017 blog, floodplains provide many benefits including flood moderation, water quality improvement, recreation and habitat diversity. (Reference 1) For this discussion, floodplains include smaller side channels, sloughs, wetlands, beaver ponds and other areas of inundation beyond the river’s main channel.

Floodplain Diversity Supports A Healthy Fishery

Fish typically escape a river’s fast flood flows in floodplains. They usually spread out and find refuge in slower moving water as the river spreads out. (Reference 2) This preserves a fish’s metabolic energy and promotes fish growth. Juvenile fish also use floodplains as nurseries as they develop and grow.

Generally speaking, the quality of a floodplain’s habitat is directly proportional to its diversity. This is because different fish species, life stages and food sources utilize different types of habitat. Diversity in aquatic and riparian habitat supports species diversity and health. Variations in water depth, water velocity, substrate composition, in-stream wood and rock formations and streamside vegetative cover all play important roles in habitat diversity and quality.

Water temperature is also an important factor with respect to floodplain suitability because fish are cold blooded. As cold floodwater enters a floodplain from the river, it spreads out, slows down, deposits sediment and warms slightly. Phytoplankton and algae – fast-growing aquatic plant life – grow as this occurs. Populations of zooplankton and other aquatic invertebrates, including insects – which comprise the main food source for juvenile fish – feed on this aquatic plant life. If water is too cold, juvenile fish are lethargic and growth is slow. If the water is too warm it causes increased metabolic demands and reduced dissolved oxygen, inhibiting growth and increasing mortality. (Reference 3)

Floodplain Habitat Beneficial for Fish Growth

A 2008 study out by the University of California, Davis (Reference 3) underscores just how important floodplains are in the development of Salmonids. (Fish belonging to the taxonomic family of Salmonidae, which includes salmon, trout, char and whitefish.) In this study, juvenile Chinook salmon were placed in two different types of enclosures when the wild salmon would naturally be rearing in fish studyfloodplain habitats in and along the Cosumnes River in California. One group of enclosure represented the open, faster water associated with the river, whereas the second group of enclosure was placed on the river’s inundated floodplain. Overall, the study concluded that the juvenile fish realized higher growth rates and lower mortality in the floodplain habitat when compared to those in the river habitat. The photo shows the juvenile salmon from these two study groups; the larger ones being the fish reared in the floodplain enclosure.

Preserve and Protect the Boise River Floodplain

Of course, a healthy, diverse floodplain must exist to support a healthy fishery. The floodplain must also be hydraulically connected to the river and not cut off by levees, roads, culverts and other barriers. Currently, the Boise River possesses these attributes only marginally as its tributaries, side channels, wetlands and other floodplain features have been sacrificed to land development over time.

brown trout

Boise Brown trout. Photo Eric Brecker

As development continues along the Boise River corridor, we must employ measures that protect, preserve and enhance the river’s floodplains to maintain the river’s native fishery and all the other benefits the river and its floodplains provide. BREN’s Boise River Enhancement Plan recommends removing or setting back confining elements like levees and re-establishing or creating side channel habitat to improve aquatic habitat. And for your safety – take a lesson from the fish – stay out of the river’s fast flowing flood water!

Mike Homza is a long-time resident of Boise; President of Stream Line Design, LLC; Vice Chair of BREN and focuses his career on a enhancing rivers, stream and their floodplains.

Reference 1

Reference 2

Reference 3


Boise: A River Runs Through It

By Charlie Woodruff, Building A Greener Idaho

Our theme of From Snow to Flow continues this week with a conversation about the Boise River with Idaho Fish and Game Regional Fisheries Manager Joe Kozfkay and Freshwater Trust Idaho Program Manager Christy Meyer. Our beloved Boise River brings life to the high desert and flows through the heart of the city on it’s way to meet the Snake. The Boise River is an incredible asset that has been taken for granted in the past. These days many individuals and groups are working hard to protect and improve its health and vitality.

We’ll talk with Joe about the Boise River fishery, how the river ran dry one day, and his favorite fish to catch. Christy will share the great work the Boise River Enhancement Network (BREN) is doing to continually improve its health and protect it from threats like the encroachment of development. BREN recently helped complete an in-stream aquatic habitat enhancement project that might just be helping little brown trout babies find shelter from these recent high flows.

Listen to the 25-minute show.

Boise River System Snow and Water Review

by Steve Sweet, PE, Quadrant Consulting

Good news, as of March 11, 2017, according to data provided by the NRCS SNOTEL sites, the Boise basin snow-water equivalent moved up 7 percentage points since earlier in the week to 152% of normal.

You can see in the Boise System Storage graph below, that as of March 10, 2017, the pesky blue line (current reservoir storage) finally pierced the red line (30-year historic average of reservoir storage).

The relatively early and significant flood risk reduction releases this year unloaded another 55 thousand acre feet (kac-ft) out of the upstream reservoirs, leaving nearly 500 kac-ft of storage available in reservoir capacity (48%).


Meanwhile, the NRCS’s March 1 Streamflow Forecast is calling for nearly 2,500 kac-ft of runoff out of the Boise River in March-July (range 2,140 – 2,750), where the 30-yr average is 1,430. The underlying message is that we’re going to need to run approximately 2,500 kac-ft through a 500 kac-ft bag in the next few months. That’ll be more than we’re accustomed to seeing.

Now that the recent rain has dogged off and the sun has come out, inflow into the system bumped up from 2,400 cfs to 6,816 cfs. Increased inflow will add just a wee bit more pressure on our reservoir bag. Last week flows on the Boise River, as measured at Glenwood Bridge, eased into the official National Weather Service “Flood Stage,” when the 7,000 cfs marker was crossed on Tuesday, March 7. Since crossing the official threshold, flows have been steadily increasing to the 7,500 cfs range we’re seeing today. The last time we saw flows this high was in May of 2012 when the river peaked at 8,310 cfs.

Water managers continued moving water into Lake Lowell through the New York Canal. Last week, Lake Lowell increased 7.5 kac-ft. If the irrigators weren’t taking that water, that’d be an additional ~1,000 cfs through town. The next time you bump into an irrigator on the street or in the field, you might just offer a heart-felt “Thanks!” for what they’re doing to reduce flood risks.

Stay tuned.

Click here for more from Steve Sweet.

Volunteers Protect Enhancement Project from Rising River

A dozen hard working volunteers pitched in on February 22 to install coconut fiber erosion control mat over topsoil at a new habitat enhancement project on the Boise River by Eckert Bridge. The $45,000 aquatic habitat enhancement project was finished late last year, but there hadn’t been time to replant vegetation and stabilize the soil before water levels began rising in the Boise River. When it was announced on Feb. 21 that water levels would rise above 5,000 cfs, project sponsor, the Ada County Environmental Advisory Board, sprang into action working with Idaho Department of Fish and Game to procure needed supplies and round up volunteers.  The disturbed ground at the two engineered log structures on the north side of the river was covered with the erosion control mat and anchored in with willow cuttings and wood stakes. The site on the south side was already fully submerged. ENEL Green Power pitched in providing volunteers and helping purchase supplies.  BREN provided volunteers and snacks. Thanks everyone.


Hard Workers


IDFG Restoration Coordinator Michael directs


Selena, Chair of Ada County Environmental Advisory Board


Zimo’s ready for fishing season


Christy from Freshwater Trust and BREN


Jeremy with ENEL Green Power


Kim lends a hand


Kyle with ENEL Green Power


Anchoring the coconut mat


Willows and wood used for stakes







BREN Assembles Collaborative Teams for Multi-Benefit Enhancement Projects

wood duckThe Boise River will have better habitat for fish and wildlife and cleaner water and more community members, including refugees, will participate in stewardship activities if funding is awarded to two BREN-facilitated collaborative enhancement projects.

Cottonwood Creek Daylighting Project

BREN partnered with the Ted Trueblood Chapter of Trout Unlimited, City of Boise, Idaho Department of Fish and Game, Boise Valley Fly Fishers, Ada County Highway District, Intermountain Bird Observatory, and Land Trust of the Treasure Valley to apply for Phase II funding from the U.S. Bureau of Reclamation Cooperative Watershed Management Program for the Cottonwood Creek Daylighting Project. The creek now flows through a buried flume underneath Julia Davis Park before discharging to the river.

Cottonwood Creek flume

Cottonwood Creek

The Boise River Enhancement Plan identifies channel confinement and simplification as the #1 issue impairing geomorphology and fisheries habitat in the Boise River and recommends daylighting tributaries to improve habitat complexity. This exciting project would create an open stream channel through the park and improve the confluence with the river to allow for fish passage.  The daylighted creek will support salmonid spawning and rearing habitat and create new wetland and riparian habitat that supports wildlife and improves water quality.

The project includes a robust engagement, education and outreach component with many opportunities for volunteers to participate.  Knowledge transfer and inspiration will support similar collaborative efforts throughout the watershed. Awards will be announced in May.

Hyatt Hidden Lakes Multicultural Habitat Project

Hyatt Hidden Lakes

Hyatt Hidden Lakes

BREN teamed up with many partners to apply for funding from the National Fish and Wildlife Federation for the Hyatt Hidden Lakes Multicultural Habitat Project. The project will engage refugees from many nations and traditional conservation stewards in transforming weed-dominated uplands at the City of Boise’s Hyatt Hidden Lakes Reserve into healthy habitat for passerine birds and non-game animals.  The Boise River Enhancement Plan identifies invasive plants as a primary issue affecting habitat function and value, and the removal of invasive plants and planting of native vegetation is a top recommendation.

Under the leadership of BREN and the Land Trust of the Treasure Valley, the collaborative project will engage existing and new volunteers, including refugees who live nearby, to remove weeds and plant native trees, shrubs and grasses on 12 acres. Volunteers will collect local seeds and grow some of the plants for the project, greatly increasing plant survival. Partners will provide on-and-off site educational programs and host field trips and work days. BREN will share stories and photos of the project to increase support for Boise River enhancement.

Partners are City of Boise, Land Trust of the Treasure Valley, Golden Eagle Audubon Society, Idaho Weed Awareness Campaign, Partners for Clean Water, The Wetlands Group, Boise State University, Idaho Office of Refugees, Idaho Department of Fish and Game, and Big Brothers Big Sisters. Awards will be announced in July.

BREN Helps Local Stakeholders Collaborate

In 2011, lower Boise River stakeholders agreed that increased cooperation, communication and networking was needed to advance ecological enhancement of the river.  The Boise River Enhancement Network was founded to provide those essential connecting services; to serve stakeholders as a “backbone” organization whose staff or volunteers plan, manage, and support enhancement work. BREN facilitated development of the Boise River Enhancement Plan in 2014/2015, maintains a website, Facebook page and email list to support communication, hosts numerous educational events each year, engages members and volunteers in reviewing, designing and implementing enhancement projects and assembles collaborative teams to pursue funding for projects like these that align with the Enhancement Plan. Please let us know how BREN can support your enhancement project.