City Releases Plan for Phase II of Boise River Park

Nearly 100 people previewed plans for the next phase of the Boise River Park at a public meeting on April 30, 2014. Preliminary designs incorporate nearly a half-mile of the Boise River and riverbank downstream from the new Harry W. Morrison Dam.

The dam was the signature structure of the first phase of the park, which opened in June 2012.

Construction is scheduled to begin this fall on the Esther Simplot Park, between the Boise River and Whitewater Boulevard, East of Veteran’s Memorial Park. The designs of the two parks are closely connected.

City officials said the proposed design for the Esther Simplot Park will replace the Farmer’s Union and Boise Valley ditch structures, reduce flood risk, improve safety, and make it possible for work to proceed on both the Simplot and the Boise River parks.

The next phase of the Boise River Park will incorporate the riverbanks, providing ample riverside viewing space and repairing the existing riverbank and preserving the functionality of the Boise River Greenbelt. 

Pending successful volunteer fundraising efforts, construction on the next phase of the Boise River Park could happen as early as late 2016. The Esther Simplot Park is being funded by the Simplot Family Foundation.

The city hired Boise-based McMillen, LLC, this summer, through a competitive bid process.  McMillen LLC, specializes in water resource projects. Scott Shipley’s company, S2O Whitewater, and the nationally recognized landscape architecture firm DHM will be partners on the project. Funding for the conceptual design was provided by the City of Boise.

River Park landscape design diverts commuter traffic, keeps boaters in the water.

The design team’s primary goal for the Boise River Park was to divert enough water for irrigators and to control river rise in the event of a major flood. Burying the existing irrigation canals will allow for a separate, elevated Greenbelt to move commuter traffic to the north side of Veteran’s Pond, reducing congestion. 

At the west end of the park, the river will be connected with Veteran’s Pond allowing boater traffic to paddle through ponds back upstream. It removes materials such as concrete from the riverbed and banks and bolsters the banks to widen the new Greenbelt. The design also increases swimming and river access, providing a beach near a new parking area.

The design for the Boise River Park, shoreline and portions of Esther Simplot Park has been divided into three distinct sections, or "reaches:”

REACH 1 – Esther Simplot Park Interface – Harry W. Morrison Dam to just upstream of Farmer’s Union

This area, just downstream from the new Harry W. Morrison Dam, will include a restroom and changing room and a parking lot. Dense native vegetation will screen Garden City residents and River Park users. A lawn area and graded shoreline with terraces will incorporate natural boulders and stone to create ADA accessible boater access, making it both easier for people to get down to the river and also for the design to handle variations in the river.

In the River, this area provides boating experiences for everyone. For many, the Esther Simplot Park and the Boise River Park will be their first whitewater experience. It is not a very steep part of the river. Large, native stones will create ripples and eddies as well as improve fish habitat. There will be two Obermeyer structures. Deflectors on shore will mesh with the riparian zone.

REACH 2 – Existing Farmer’s Union Diversion

This area currently features a steep riverbank with little vegetation, and concrete chunks in the River. The design creates an overlook with an ornamental railing. A sloped lawn will bring people to the river, and compliment a terraced lawn seating area and plaza. The design incorporates existing trees.

There will be a designated take-out area below the last of three structures, but it will be one of many opportunities to get in and out of the water. Eddies and slack water will create gentle spaces where people can walk out into the water. The area is ADA accessible. All concrete, debris and invasive vegetation will be removed wherever possible.

This area includes a significant drop in the river, and the potential for the centerpiece of the design. In all, three drops have been incorporated into the plan. The uppermost utilizes a wide-crested weir with Obermeyer flap gates. The lowermost will be for beginner/intermediate paddlers with a less forceful wave. All of the structures are non-adjustable.

REACH 3 – Downstream of Farmer’s Union to downstream end of Veteran’s Pond

The design on the shoreline of this section incorporates the main trail along Farmer’s Union tying into an existing trail at Veteran’s Park. The banks will be sloped gently for an accessible shoreline.

The in water design will incorporate the beautiful natural character of the river, augmenting what exists and not altering the character of the river. The flow will be offset with diversions and boulders. In stream structures will create fishing benefits. An eddy will create a new takeout location.

Next Steps and Timeline (as of March 2014)

• Integrate the Phase II Water Park Features into the river flood hydraulic model
• Update and refine the conceptual design configuration with input from February 2014 public meeting
• Prepare a draft conceptual design report including cost estimates and schedule
• Advance fund raising efforts
• Conduct a second public meeting to present updated conceptual design

History of the Boise River Park

Construction of Phase I of the long-awaited Boise River Park was dedicated June 2012. Since then, paddlers and surfers have enjoyed waves created by the main feature of the park: the Harry Morrison Dam (formerly the Thurman Mill Diversion, or 36th Street Wave). Organizers and the City of Boise are currently working to design and fundraise for features and shoreline enhancements downstream.

The park is located near downtown Boise between Main Street and Veteran's Memorial Parkway. A temporary parking and access map is here.

A highlight of the $3.6 million project is two state-of-the-art Wave Shapers designed with pneumatically-operated air bladders that inflate to elevate stainless steel flashboards. City employed wave technicians adjust the flashboards to control the size and shape of the waves, while ensuring irrigation water is consistent.

At normal river flows, the Wave Shapers create an approximately 20-foot wide primary wave and a longer 25-foot secondary wave suitable for "green wave" surfing. The structure's adjustability allows alternating features at nearly every water level throughout the year. During the winter of 2013, the structure will undergo modifications to improve function and adjustability in the higher water seasons when paddling is popular.

Shoreline enhancements accommodate hundreds of spectators. A plaza area features benches named in recognition of significant gifts, some memorialize prominent paddlers. The former Thurman Mill Diversion was named the Harry Morrison Dam in recognition of a combined gift of retirees of the Morrison Knudson Company and Boise Legacy Contractors.

Future phases of the Park will dovetail with the development of the adjacent Esther Simplot Park, which the Simplot family is funding, making it possible to schedule its construction beginning in the fall of 2014.

Planning and design for upcoming phases of the Boise River Park will begin in the coming months, as the Esther Simplot Park moves forward. The City has secured a contract with a water park designer and construction company and dedicated funding to design and documentation. Preliminary designs and a construction budget are expected in the spring of 2014.

Wave riders and others can keep tabs on what is happening on the Boise River Park on Facebook.