Monitoring Shows Progress Towards Reducing Boise River Phosphorus Levels

By Lauren Perreault, USGS

For decades, the lower Boise River downstream of Lucky Peak Reservoir has been highly enriched with phosphorus. Too much of a good thing, the high concentrations of phosphorus create a cycle of excessive plant growth, decreased oxygen for fish, and even algal blooms. But things may be turning around. Water-quality monitoring by the U.S. Geological Survey (USGS) shows that phosphorus concentrations in the lower Boise River are down one third since 2015.

From below Lucky Peak Dam to the confluence near Parma, the Boise River winds through cities, towns and farmlands, and that takes a toll on its water. While the river is relatively cold and clear upstream at places like Barber Park, it becomes warmer, carries more sediment, and contains more aquatic plant life as it moves downstream to its mouth near Parma. These changes are caused in part by increased amounts of phosphorus in the river, which cause problems by increasing plant growth. Besides being a nuisance to recreationists, this excess plant matter consumes oxygen that is dissolved in the water when it decays, and too little dissolved oxygen is harmful to fish and other aquatic life.

The Boise River near Barber Park above the City of Boise is relatively cold and clear, versus the Boise River near Parma is warmer, carries more sediment, and has more excess aquatic plant growth.

So where does the excess phosphorus come from? The short answer is: all of us. A little bit of it comes from water and soil runoff from forested lands upstream. Municipal wastewater contains lots of phosphorus, and while much of it is removed during the treatment process, some is still in the water when it’s released back into the river. Fertilizers often contain phosphorus, and soil and water runoff from lawns and fields can carry some of this phosphorus into the river. Some phosphorus also comes from shallow groundwater. This phosphorus may come from leaky septic systems and from the application of both fertilizer and irrigation water that already has a lot of phosphorus in it from upstream sources. After it’s applied to fields, this water and phosphorus can infiltrate into shallow groundwater and eventually makes its way into the river.

Recognizing these impacts, the Idaho Department of Environmental Quality (DEQ) established total phosphorus limits for the lower Boise River in 2015 to address water quality issues. The U.S. Geological Survey has worked with DEQ and the Lower Boise Watershed Council to monitor water quality in the Boise River since the 1970s. This partnership brings local stakeholders on the Council, including cities, irrigation districts, and industries, together with local regulators and federal resources to help understand and solve problems here in Idaho.

Most recently, the USGS has been collecting water quality samples six times a year from the Boise River between Star and Middleton, and from near Parma. These samples are analyzed for a variety of constituents, including phosphorus and other nutrients. Partnering with the City of Boise, the USGS also uses an automatic sampler to collect samples every 49 hours from the Boise River near Parma; these samples are analyzed for total phosphorus (phosphorus in all forms). By comparing the phosphorus in these recent samples to previous data, the USGS has recently shown that phosphorus in the Boise River near Parma decreased by about one third (36 percent) over the past two years. From 1987 to 2012, the average annual phosphorus concentration (the mass of phosphorus per a volume of water) was 0.32 milligrams per liter (mg/L). The average total phosphorus concentration from 2015 through 2017 was 0.21 mg/L. So in the past two years, total phosphorus has declined by almost half of the amount needed to achieve the water quality target, which is 0.07 mg/L.  Although the high flows in spring 2017 helped dilute phosphorus in the river, the overall decline was apparent well before these record spring flows.

Monthly average measured phosphorus in the Boise River near Parma is lower than previous phosphorus levels. The difference is biggest during the winter. The difference is smallest during irrigation season (May through October) and storms.

This reduction is good news for the Boise River, and shows that work done throughout the basin to reduce phosphorus inputs is having an impact. Best management practices installed to reduce soil erosion and water runoff are likely making a difference in agricultural inputs. In the meantime, cities throughout the Treasure Valley have been upgrading their wastewater treatment facilities and removing more phosphorus than before. One way to understand the impact of these upgrades is to look at loads. Similar to concentration, a load is the mass of phosphorus but per a set unit of time. In this case, the load refers to the mass of phosphorus that moves through the Boise River near Parma in a day.

From 2012 to 2013, the average annual wastewater phosphorus load from Boise, Meridian, Nampa and Caldwell was about 1387 pounds per day (lb/day). During 2015 to 2017, this load decreased by about 50 percent to 644 pounds per day. During the same time, the total Boise River load near Parma decreased about 30 percent from its previous level, 2398 lb/day, to 1653 lb/day.

The municipal wastewater phosphorus load has decreased by about 50 percent over the past two years. This has helped decrease the total phosphorus load in the Boise River near Parma, but further reductions are needed, particularly during storms and the irrigation season.

However, the biggest improvement comes during the non-irrigation season, when the municipal load represents the greatest proportion of the total phosphorus load in the Boise River near Parma. This shows that although good progress has been made towards meeting the phosphorus target – and improving water quality – there is a lot more progress to be made by all of us.

Fortunately, many irrigators are working to install new water and erosion control structures, municipalities continue to upgrade their facilities, and innovative projects are intercepting and cleaning up phosphorus-laden waters throughout the valley. Continued water quality monitoring in the lower Boise River will track the progress made by these improvements, as fish, recreationists and the river reap the benefits.

Citizen Science! Boise Watershed Watch

by Kati Carberry, BREN Coordinating Team Chair

Hi Fellow Boise River Enthusiasts,

The Boise River Watershed Watch Day is coming up on Saturday September 30th from 10:00-12:00.  Watershed Watch is a great program led by the Boise Watershed where a Team Leader and a group of citizen scientists monitor an assigned surface water site along the Boise River. On the day of the event more than 20 sites from Lucky Peak to Caldwell will be monitored for DO, pH, turbidity, Temp, bacteria, TSS, TP, macroinvertebrates, and invasive species. Watershed Watch is the perfect way to get kids engaged in science.

Figure 1. Watershed Watch volunteers identifying macroinvertebrates

Clean water is essential to support healthy fisheries, wildlife habitat and ecosystem function in addition to drinking, irrigation and recreation. Water quality enhancement is a goal of BREN, and a number of strategies are described in the Boise River Enhancement Plan. Many water quality reports for the lower Boise River can be accessed through our website.

BREN is going to be monitoring two sites this year, one at the Star Bridge and one at the Linder Bridge. If you would like to volunteer as a citizen scientist at a BREN site (Linder Bridge or Star Bridge), please sign up. I really think all of you would enjoy this one day event, and it is a great opportunity for your friends and family to become involved with BREN.

This will be the 10th consecutive year of Watershed Watch and it is amazing to see the amount of historical data that has been collected on the Boise River from this one day annual event. Below is a link to more information and how to register.  Feel free to pass this on to anyone else you think would be interested.!/  Register Here

Registering is super easy and quick. Once you are at the site, click on the link to register in the middle of the page. From there you will be asked to fill out a simple registration form. Please make sure to select the Linder Bridge Site in Eagle site # 29, or the Star Rd. Bridge site # 25 (see below for website images).

See you on September 30!


What’s that Scum? Perhaps it’s a Harmful Algal Bloom…

By Graham Freeman, Idaho DEQ

Harmful Algae Blooms (HABs) seem to be making all of the news these days, from newspapers to national television, from Florida to Washington and most places in between.  So what exactly are Harmful Algal Blooms and why are they such a hot subject right now? Let’s dive in, or maybe we should observe from the shore…

Cyanobacteria, also known as blue-green algae, are single celled, prokaryotes that have been around for billions of years. Similar to green algae (eukaryotes), cyanobacteria uses photosynthesis to create sugars and releases oxygen as a byproduct of this chemical reaction.  Cyanobacteria are often credited for oxygenating the atmosphere billions of years ago.  When cyanobacteria rapidly reproduce in aquatic environments they create blooms with hundreds of millions of cyanobacteria cells.

We often refer to cyanobacteria blooms as Harmful Algae Blooms for several different reasons.  First and most obvious, cyanobacteria blooms are often smelly and unsightly.  Not many people want to swim or fish in waterbodies that look akin to slime you might see in an episode of the Simpsons.  Secondly, algae cells from any type of bloom, harmful or otherwise, eventually die off.  Once the cells die off, decomposition sets in and scavenger bacteria consume the dissolved oxygen from the water.  If the rate of cell death is rapid enough or large enough, dissolved oxygen concentrations can drop low enough to stress or kill fish and other aquatic organisms.  Finally, certain taxa of cyanobacteria are known producers of toxins, which are potentially toxic to humans, pets, livestock, and other wildlife.

Cyanotoxins are toxins produced by cyanobacteria and are considered some of the most poisonous naturally occurring substances.  Cyanotoxins generally fall into a couple of different chemical classes that are known to damage to the liver, interfere with the nervous system, cause cancer, irritate the skin,  and new research is showing that some cyanotoxins may play a role in neuro-degenerative conditions such as ALS and Alzheimer’s. More info on cyanotoxins can be found here  on Environmental Protection Agency’s website.  While there are thousands of different cyanobacteria species, remember that most cyanobacteria do not produce cyanotoxins. Additionally, some species of known toxin producing cyanobacteria may not produce cyanotoxins one day and begin to produce toxins the next day. Most people will assume that cyanotoxins are produced to stop planktovors (animals that eat plankton) from eating the cyanobacteria. However, it appears that this isn’t necessarily the case. Research indicates that cyanotoxins may be used by cyanobacteria in their normal metabolic processes, for nutrient uptake, for example.

If you follow the news closely, you’ve probably heard about HABs or at least some of the problems associated with cyanobacteria blooms.  In 2014, a HAB contaminated a drinking water source leaving hundreds of thousands of people without water in Ohio.  Just this year, 32 cattle were killed by a Harmful Algae Bloom in Oregon.   In 2016, 11 confirmed HABs were reported on Idaho’s lake and rivers.  During the first half of the summer of 2017, there have already been seven confirmed HABs.

Anecdotally, it appears that HABs are increasing in frequency and intensity across the nation.  This could be a product of the public being more informed and therefore reporting more blooms or it could be a product of poor water quality.  In the United States there are over 100,000 miles of rivers and streams, 2.5 million acres of lakes, reservoirs, and ponds, and more than 800 square miles of bays and estuaries that have poor water quality due to excess nutrients (nitrogen and phosphorus).  Cyanobacteria are commonly associated with nutrient, specifically phosphorus, enriched waters.   Additionally, at warmer water temperatures cyanobacteria reproduce more quickly and can out-compete nontoxic green algae.  If the average global temperature continues to rise, we may see many more HABs on nutrient enriched waterbodies.

Now that you all know a little about cyanobacteria, cyanotoxins, and HABs – let’s talk about identifying and avoiding the blooms. Cyanobacteria blooms can take on many different colors and structure depending on the composition of the bloom. Often times cyanobacteria blooms cause surface scum that looks like spilled paint, with blue, green, and white colors.  Some blooms will cause the water to look like pea soup. Because of wind and wave action, HABs are known to accumulate around shores of lakes and reservoirs, which can be particularly dangerous to animals looking for a drink.  It is difficult to visually confirm a HAB and it is impossible to tell if a bloom is toxic through visual observation. Because HABs are difficult to identify, we encourage people to avoid contact with all suspicious looking water and report suspected blooms to the local Public Health District, waterbody manager, or the Department of Environmental Quality.   If you are in doubt of the condition or safety of the water, stay out of the water. When in doubt, stay out!

The majority of the cyanobacteria exist in aquatic ecosystems without causing any problems.  When conditions get just right, cyanobacteria begins to multiply and can create HABs, which are potentially toxic to humans, livestock, and other wildlife.  Right now, there are not many short term solutions to reducing or eliminating HABs.  Efforts to reduce HABs should focus on improving water quality, specifically reducing the inputs of nutrients to waterbodies.  Reducing fertilizer inputs on agricultural fields, reducing erosion, and improving wastewater treatment processes are ways to limit phosphorus load to waterbodies.  Additionally, we can all do our part by limiting fertilizer applications on residential lawns and cleaning up pet waste.

For more information on HABs and current water quality advisories in Idaho, please visit this website.






Barber Pool – A Completely Different River Experience

by Tom “Chel” Chelstrom

Dipped my paddle

In the cool clear water

Canoe slices through

Like a sleek river otter


Paddle ‘round the bend

What will you see

Splashy little riffle

Or a sweet eddy

People define ideal river trips in different ways. The Boise River “town stretch” from Barber Park to Ann Morrison Park is Idaho’s most popular day trip, evidenced by over 100,000 floaters every year. It’s a great day on the river, with gear rentals, shuttles, a river channel maintained for recreation and emergency help nearby.

Just upstream from the town stretch, the Barber Pool provides a completely different river experience for those willing to exchange some energy and portaging skills for a more personal view of the river. Portions of the Barber Pool are visible from Diversion Dam, the highway 21 bridge, the greenbelt and the Oregon Trail Reserve. I think the best way to experience the Barber Pool is on the water; to do that you have to portage- carry your gear to the river and around obstructions. The reward is a wildlife-rich escape from the busy urban river downstream.

The Barber Dam was built in 1906. The dam created the Barber Pool, a pond for logs headed to the mill.  Today, it is administered by the Idaho Foundation for Parks and Lands, and serves as a conservation and research area. There are three challenging portages in the three miles from Diversion Dam to Barber Park.

Parking is available at Lucky Peak State Park- Discovery Picnic area and at Diversion Dam. The small reservoir between Discovery Park and Diversion Dam is a great place to practice paddling forwards, backwards and sideways; ferry across the current and get in and out of eddies.

There is no marked or maintained portage around Diversion Dam. Take out at the buoys and hike up a steep, slippery rock bank on river right (the right bank of the river as you are facing downstream). Walk down the greenbelt and look for a faint path to the river near the old cable car. Watch out for the abundant poison ivy in this area. This is a bushwhack for the determined. The reward is close to a mile of seldom paddled river.

A simpler way to enter the Barber Pool is to park in the large, undeveloped parking area on river right, just downstream of the Idaho Highway 21 bridge. You’ll see a few obvious but unimproved, steep and slippery paths leading down to the river.  After you cross the greenbelt and hike down to the floodplain, take a moment to marvel at the scouring and regrowth from this year’s flooding! Hike another few minutes under the bridge and you will be at a nice beach and put-in.

Floating Barber Pool

The next couple of river miles are perfect for easy floating, fishing and wildlife watching. Look for a sign reading “keep right, portage ahead” posted on the head of an island, about a mile and a half downstream of Idaho 21 bridge. The Barber Dam portage is another half mile downstream of the sign.

Barber Dam has the most obvious, developed portage on the Boise River. Look for a large wooden staircase on river right. Follow the signs; it’s a few hundred yards around the dam and chain-link fence to the put in.

Downstream from Barber Dam, a short paddle through a rarely seen stretch of the Boise River leads to the Nampa- Meridian Irrigation District’s Ridenbaugh Canal diversion. Portage on river right. Take out at Eckert Road/ Barber Park, or paddle on another 60+- miles to the Snake River confluence. You can learn more about boating the Boise River by consulting the Boise River Water Trail Guide and Interactive Google Tour. Please note that this year’s high water caused major river channel changes, so please boat responsibly.

The Barber Pool is an urban adventure!

Seeking Nominations for BREN Coordinating Team

We’re looking for BREN members to join our Coordinating Team!

BREN Coordinating Team
The Boise River is shared among everyone in the Treasure Valley, and BREN membership and leadership is inclusive. Land owners, water users, consultants, researchers, resource managers, river recreation enthusiasts, teachers, environmental advocates, government workers, water managers, business owners and all those who live, work and play in the Boise River Watershed are encouraged to apply.

The BREN Coordinating Team is elected by the General Members to act on behalf of BREN. Nominations for 7 seats on the BREN Coordinating Team are now open. Please complete this Coordinating Team application by August 31, 2017. We hope you will apply!

Responsibilities and Election Process

The Coordinating Team is delegated the authority to act on behalf of the Boise River Enhancement Network:

  • The Coordinating  Team  will  provide  direction  to  BREN  in  order  to  achieve BREN’s vision, including setting goals, policies and procedures
  • The Coordinating Team will hold at least 6 meetings per year
  • Each member of the Coordinating Team will participate in most of the Coordinating Team  meetings  each  year,  demonstrate  a  commitment  to  BREN  through  involvement  in  BREN work and cooperate with others to fulfill BREN’s vision.

The Coordinating Team election will be held online for seven days starting September 18, 2017. All BREN members are eligible to cast one vote for each of the vacant Team seats. If there are more candidates than Team seats, then the candidates with the most votes will be elected.

E. coli Plagues Local Pond

By Kate Harris, City of Boise

You may have seen the “Pond Closed” signs at City of Boise ponds this year or heard about the City’s decision to close Esther Simplot Park to dogs.  The City closed both Quinn’s Pond and Esther Simplot Park ponds on June 21 due to E. coli concerns.  Quinn’s Pond was reopened on June 30th, while Esther Simplot Park ponds remain closed. The City of Boise has a robust water quality sampling program in place, and staff are working to reduce bacteria concentrations and reopen Esther Simplot Park ponds as quickly as possible.

Esther Simplot Park

Esther Simplot Park Photo City of Boise

Water Quality Monitoring Protocol

The City of Boise worked with the Idaho Department of Environmental Quality and Central District Health in 2013 to formalize monitoring, reporting, and public notification protocols.  The City collects E. coli bacteria samples in City-owned ponds specifically designated for swimming weekly, April 1 – September 30th.  E. coli concentrations are evaluated based on Idaho water quality standards. If a sample exceeds 235 CFU/100 mL, or exceeds the geometric mean of 126 CFU/100 Ml, the City increases the sampling frequency (daily M-F) to closely monitor bacteria levels. The City currently monitors Esther Simplot Park ponds, Quinn’s Pond and recently added Veteran’s Park pond although it is not specifically designated for swimming.

Microbial Source Tracking

The City of Boise contracted with a laboratory to help determine the sources of fecal bacteria in Quinn’s Pond and the ponds at Esther Simplot Park.  Source Molecular used fecal Bacteroidetes, a phylum of bacteria found primarily in the intestinal tracts and mucous membranes of warm blooded animals for source tracking, to identify the fecal bacteria sources. The City of Boise is still collecting data to complete a robust study, but three consecutive samples (each separated by at least a week) confirmed the presence of dog and goose fecal biomarkers in the ponds.

The City Takes Action

The City closed both Bernadine Quinn and Esther Simplot Parks to dogs.  One gram of goose poop (1 gram equals approximately the weight of a business card) contains 10,000 fecal coliforms, while one gram of dog poop contains 23 million fecal coliforms.  One good size dog pile can have 3 BILLION fecal coliform bacteria in it!!

Canada geese

Canada geese Photo Ken Miracle

To reduce the impact of geese, the City has increased geese “hazing” activities in the pond and along its banks.  Geese are herded off the ponds and annoyed several times a day to encourage them to move.  In addition, poop cleanup activities have increased in the Park, especially along the beaches and areas that runoff into the pond.

People were also identified as a source of fecal bacteria to Esther Simplot Park ponds. The City confirmed there is no wastewater connection to the City of Boise collection system (sewer) and are working to confirm that private systems in the area are also not contributing sources.

While the major sources have been identified and are being reduced as much as possible, the City is continuing to research all of the ways that the bacteria is entering the pond (stormwater sources in the area, runoff from irrigation, sediment sampling, etc.). DNA studies are also continuing.

The City is investigating the feasibility of moving more water through the ponds in the future.

Cooperation and Gratitude

The City of Boise has been working closely with other agencies to ensure that we are protecting public health, and providing public notification, to investigate potential treatment options, and to reduce the likelihood of elevated E. coli concentrations from entering the ponds in future years.  In particular, the City would like to thank Lance Holloway and Idaho Department of Environmental Quality staff, Christine Myron and Central District Health staff, and staff from the Idaho Department of Fish and Game.

Click here for Kate’s full article that includes water quality monitoring data

LTTV & BREN Awarded Grant from National Fish and Wildlife Foundation

It’s another win for enhancement! The Land Trust of The Treasure Valley (LTTV) and BREN have been awarded a grant by the National Fish and Wildlife Foundation to restore upland and wetland/riparian habitat at the Hyatt Hidden Lakes Reserve in Boise, Idaho.

The 44-acre wildlife reserve is owned by the City of Boise and provides extensive wetland habitat and sagebrush, grass and shrub upland habitat in an otherwise urban setting. Over 150 bird species have been documented using the site, along with bats and other non-game animals. The site also treats stormwater; a vegetated sand filter treats stormwater from 57 acres before it flows into the Reserve’s wetlands and then to the Boise River less than one mile away, thus buffering the effects of urban runoff on the Boise River. However, a recent survey shows 58% of the plant species are exotic non-natives. The uplands are especially overrun with undesirable species including cheatgrass, quackgrass, kochia, tumblemustard, and Queen Anne’s lace. These invasive plants cause a marked reduction in biodiversity as well as a significant fire risk to the Reserve and surrounding neighborhoods.

The grant will be used to restore native vegetation by removing weeds and cultivating and planting native plants on 12 acres. Many partners including LTTV, Intermountain Bird Observatory, The Wetlands Group LLC, and Idaho Weed Awareness Campaign will serve on the expert team to ensure the work plan is scientifically sound. Under the leadership of BREN and the Land Trust of the Treasure Valley, experts and community members will create and implement a habitat restoration work plan that includes 5-year goals, timelines, assignments and evaluation criteria making it possible for the City of Boise to realize the full potential of this easily-accessible urban reserve. We are also partnering with Big Brothers Big Sisters and the Idaho Office of Refugees to develop a multicultural stewardship program that provides outreach and engagement to low-income and refugee populations.

Stay tuned for more information on this project in the months to come!


Plant List for Riparian Enhancement

By Roger Rosentreter PhD, plant ecologist and river lover:

High water!  Means you have an opportunity to improve your little bit of the Boise River. Control of invasive species to improve the function and value of critical riparian habitat is a top recommendation of the Boise River Enhancement Plan, and now’s the time everyone can make a difference.

Invasive weed Amorpha fruiticosa

High water has come and gone and public and private riverside land stewards can take advantage of the changes in soil deposition or loss to enhance riparian vegetation. Whether it’s an area that was inundated for months or a bank that’s in need of stabilization, landowners should plant good and remove bad plants for a healthier, more flood-resilient river.

Brown Trout. Photo Eric Brecker

Native vegetation provides food for insects, both terrestrial and aquatic. Native cottonwoods and willows leaves are shredded by aquatic insects and these insects provide food for fish in the Boise River. This is part of Mother Nature’s food web. In contrast, exotic trees and shrubs like Russian olives and lead plant (Amorpha fruiticosa) have leaves with hairs or oils that native insects have not evolved to eat. Native insects have taken thousands of years to co-evolve with native plants. Leaves from Russian olive trees fall into the Boise River come autumn and are similar to inorganic trash, rather than part of the food web. These exotic trees and shrubs are not good for our Boise River fish.

Many cities prohibit the removal or destruction of native plants in the riparian area, so know before you pull or cut anything. My plant list (below) contains the most common and easily planted and maintained native species. For help identifying or sourcing native plants ask local nursery staff, Idaho Botanical Garden staff, and read the Idaho Native Plant Society booklet, Landscaping with Native Plants of the Intermountain Region.

Plants recommended for planting along the Boise River.  Compiled by: Roger Rosentreter.

Common Name  Genus and Species Notes
Red-osier dogwood Cornus sericea (stolonifera) Red stems
Woods’ rose Rosa woodsii Small straight thorns, native
Silver sagebrush Artemisia cana Tolerates ephemeral flooding, for dry sites near the river
Willows Salix spp. Shrub type willows
Oak leaf sumac Rhus trilobata (Grow low type or the regular taller shrub) Drought tolerant, firewise, native
Golden currant Ribes aureum Early spring flowers, drought tolerant
Black Cottonwoods Populus spp. Tall trees
Chokecherry Prunus virginiana Tall shrubs
Netleaf hackberry Celtis reticulata For dry rocky places near the river
Louisiana sage Artemisia ludoviciana Herbaceous sage
Goldenrod Solidago Canadensis or others Herbaceous, butterfly attractant
Willow aster Aster hesperius Tolerates flooding
Milkweed Asclepias speciosa Monarch butterflies, rhizomatous
   GRASSES, and grass-like plants  
Canada bluegrass Poa compressa Tolerates saturated and dry soils, use seeds not plants. Short drought tolerant sod forming grass
Great Basin  wildrye Elymus cinereus Tall bunch grass
Sheep fescue Festuca ovina short drought tolerant bunchgrass




What is growing along the Boise River?

This year’s high river flows deposited sediment and scoured new ground surfaces for a variety of native and non-native plants to grow. So what is growing along the Boise River? Thanks to wetland expert Chris Murphy from the Idaho Department of Fish and Game, joined by botanist Dr. Roger Rosentreter and riparian ecologist Dr. Rob Tiedemann, BREN members got an up-close look at numerous seedlings, saplings, herbs and grasses.

Black Cottonwood

Black cottonwood (Populus trichocarpa) seedlings were growing in abundance along newly deposited sediment. Cottonwood seedlings are identifiable by their red stems and serrated leaves. Unfortunately, most of these seedlings will not survive because the river flows were drawn down too rapidly, lowering the water table below their rooting zone.

How can you tell between a cottonwood sucker and a sapling grown from a seed? Look at the base of the plant. The sucker will be thicker along the base where it has emerged from the root system of a mature cottonwood tree. Suckers are genetically identical to the parent tree, whereas cottonwood seedlings provide genetic diversity.

Black cottonwoods are considered a keystone species in the Boise River system, as many wildlife species rely on cottonwood for critical habitat. For an in-depth discussion on black cottonwood and river flows, please refer to Dr. Tiedemann’s blog on the subject.

False indigo

As a seedling, false indigo (Amorpha fruticosa L.) looks kind of like black cottonwood – but don’t be fooled! False indigo seedlings are distinguishable by rounder, non-serrated leaves that grow opposite from each other. Unlike the cottonwood seedlings, false indigo is tolerant of drier soils. So if you see it, pull it! False indigo has become invasive along the Boise River, easily outcompeting most native woody shrub species.

A tribute to their robust rood systems, these mature false indigo plants survived through weeks of inundation and force from the river.

Wood’s rose

Another look-alike, Wood’s rose (Rosa woodsii) kind of looks like false indigo but notice the shorter, serrated leaves and of course, the thorns. Wood’s rose is an important native shrub species.

Non-native Trees

We saw numerous silver maple and catalpa seedlings. Both are non-native, so does that make them “bad”? On one hand, they take up space where native trees, such as the cottonwood, could otherwise grow. But on the other hand, they provide important habitat and are better suited for reproduction in the regulated Boise River system.

Are there any trees that should be removed? Scientists are not all in agreement, but our experts list tamarisk (Tamarix spp.), tree-of-heaven (Ailanthus altissima) and Russian olive (Elaeagnus angustifolia) as the worst offenders, as they alter the surrounding environment to their own benefit and at the expense of natives, provide marginal habitat for wildlife, and are largely left alone by insects. In short, they don’t participate in the ecosystem.

Other weedy plants

Numerous weedy plants have quickly established themselves on the newly formed and cleared surfaces, such as pigweed (Amaranthus retroflexus), pinappleweed (Matricaria discoidea), jointed goatgrass (Aegilops cylindrica) and quackgrass (Elymus repens).

So what’s growing along the Boise River? A lot of the same plants, including invasives, that were established along the river before the high water. The best thing riverfront homeowners and volunteer groups can do to help natives plants thrive is to remove noxious and invasive species. Learn more about the importance of native riparian habitat  in the Boise River Enhancement Plan. If you’re interested in learning more, consider becoming a Weed Warrior!





BREN Receives BOR WaterSmart Grant!

We have great news for the Boise River – the Boise River Enhancement Network has been awarded $100,000 by the U.S. Bureau of Reclamation to implement Phase II of the WaterSMART Cooperative Watershed Management Program! The grant was submitted and supported with the following partners: Ted Trueblood Chapter of Trout Unlimited, City of Boise, The Land Trust of the Treasure Valley, Intermountain Bird Observatory, Idaho Department of Fish and Game, Boise Valley Fly Fishers, and the Ada County Highway District.

Project funds will be used to restore the natural function of the last 440 feet of Cottonwood Creek where it enters the Boise River in Julia Davis Park in downtown Boise. Cottonwood Creek is currently buried in a flume starting where it enters the city, and ending in a concrete and stone outlet that dumps into the Boise River. Once ‘daylighted,’ Cottonwood Creek will provide an array of ecological, educational and aesthetic benefits. The Boise River Enhancement Plan recommends daylighting tributaries to improve habitat complexity and geomorphic function of the river.











(Cottonwood Creek Daylighting Initial Design)

The project will provide new instream fish habitat to support spawning, rearing, and over-wintering, all of which are limiting to the Boise River fishery. Native whitefish, native sculpin, and naturally spawning rainbow and brown trout will benefit from this project. Completion of this project will also create 0.35 acres of riparian and wetland habitat providing new habitat for native wildlife and improving water quality through the capture, filter and removal of pollutants.

Daylighting Cottonwood Creek has been in the master plan for the park as well as in the City of Boise’s master plan for more than 15 years. Funds will be used in the first year to update and revise the 2003 project plan developed by the Ted Trueblood Chapter of Trout Unlimited and in the second year to construct the channel and review performance. The estimated completion date is September 30, 2019.

The project includes a robust engagement, education and outreach component with many opportunities for volunteers to participate (see timeline below). Stay tuned!

Activities and milestones for the Cottonwood Creek Daylighting project.

Date(s) Activity
Oct – Dec 2017 1)      Formalize partnerships with cooperators: City of Boise (both Boise Parks and Recreation and Public Works), Boise State University, US Forest Service, Idaho Department of Fish and Game, Army Corps of Engineers, Ada County Highway District, and Idaho Department of Water Resources.

2)      Create Community Engagement Workplan that describes the kinds of community engagement and volunteers (professional, manual labor, skilled, etc.) needed, when needed, and who is responsible for recruitment including a calendar of planned community engagement opportunities (e.g open house, willow planting).  The plan will also establish quantifiable goals for engagement.

3)      Create a Community Engagement database and use it to track community engagement and volunteer activity.

4)      Create a Public Relations Workplan that includes dates for press releases, media tours, public events, blogs, presentations, videos, project updates, describes the social media strategy, and assigns responsibilities. Goals for number of people reached will be established.

5)   Create a Knowledge Transfer workplan that includes tasks and a timeline to ensure that knowledge of the project, including design, permitting, partnership creation, construction, community engagement and monitoring, is transferred to other stakeholders in the watershed to support Boise River enhancement. Goals for the number of stakeholders reached in Ada and in Canyon counties will be established.

6)   Create a plant palate and planting plan: The Land Trust will work with the Intermountain Bird Observatory and local restoration and water quality experts to create the planting palate desired and a site plan to guide the planting effort.

7)   Cottonwood seedlings will be grown from seed collected nearby which will help get a jump start on the enhancement effort. Volunteer effort will begin.

8)   Additional plant material will be grown by the Land Trust and its partners over the course of the project, building an inventory for enhancement for this specific project.

Jan. – June 2018 1)      Update technical design and develop work plan and monitoring plan of daylighting project.

2)      Provide opportunities for public input on design.

3)     Seeds will be collected and riparian shrub cuttings will be prepared for planting.

April 2018 Develop RFPs for Contractors: clearing & grubbing; asphalt removal; irrigation demo, temporary supply, final repair; excavation of channel; plants; turf replacement; concrete & asphalt; park elements.
July 2018 Secure all necessary permits
July 2018 1)      Promote the daylighting project in local media and with target audiences.

2)      Secure balance of implementation funds needed.

July 2018 Selection of Contractors; Contracts Established
Sept 2018 1)      Community Engagement Report that tracks numbers of volunteers, jobs accomplished, hours volunteered and basic demographic data.

2)      Communication/Education Annual Report that describes public relations and knowledge transfer activities and results.

Oct 2018 – Feb 2019 Construction window:
Day 1 Survey
Day 2 -3 Turf Clearing & Grubbing; Irrigation Preparation
Day 4 – 10 Earthwork – excavation of channel; grading; install gravels
Day 7 – 9 Headwall & Railing at Daylighting point
Day 11 – 14 Installations: interpretive kiosks, park elements, irrigation
Day 15 – 16 Landscaping
3 months after up to 5 years Assess Performance Measures: Water Quality, Fish presence, etc., as determined in monitoring plan
6 months after award Semi-Annual Performance Report
9 months after award 270-day Performance Report
Sept 30, 2019 1)      Final Performance Report

2)      Community Engagement Report that tracks numbers of volunteers, jobs accomplished, hours volunteered and basic demographic data.

3)      Communication/Education Annual Report that describes public relations and knowledge transfer activities and results.