Plans beginning to take shape for future work on Harriman Canal and angler trails along the Henry's Fork

Plastic dams holding the Harriman Canal together November 2014

With the opening of the Ranch this week, it was time to get out a little bit of information about future projects that will enhance the experience of visitors to this hallowed water and protect the Henry's Fork and its wild trout.

Harriman Canal Project Overview

Numerous anglers and HFF members have called attention to the condition of the trails below the fishermen’s access at the north end of Harriman State Park. An initial review of the problem led to a comprehensive look at the irrigation infrastructure and management of the resources in the immediate area. The major issues include management of the Harriman Canal (or lack thereof) for winter fish use, fish mortality in the canal, decay of infrastructure, sediment deposition in the river, safety and erosion issues along the angler trail that parallels the upper portion of the canal, and general operation and management of the canal.

The State of Idaho Department of Parks and Recreation holds a natural-flow water right at this point of diversion for 30 cfs with a priority date of 1891 and 5 cfs with a priority of 1898. Together, these water rights allow irrigation of 455 acres, which is used as pasture for late-season cattle grazing in the park. These water rights are in priority for the majority of the irrigation season in most years. Water rights in Idaho are extremely valuable, and Harriman State Park must continue to utilize the water right to protect it. A later water right was designated to protect fish inhabiting the canal during the winter. This 10 cfs water right is in priority as long as there is 300 cfs in the river at the point of diversion.

Seepage from the canal into the soil and underlying geologic material may be at least partly responsible for saturating the areas between the canal and the river across which the angler trail passes. Canal seepage is universal across the Snake River basin and has become an important component of the hydrologic characteristics of the basin. Where small canals and ditches are used for flood irrigation of pasture—as in HSP—canal seepage is a desirable and necessary component of the irrigation system. However, in this case, seepage along the upper portion of the canal does not serve an irrigation purpose and compromises the experience of anglers walking downstream from the upper parking lot.

Given that the canal is in visible disrepair, Harriman State Park and the Henry’s Fork Foundation envision a project that repairs Harriman Canal, installs a fish screen at the point of diversion, updates irrigation infrastructure, and minimizes damage to the riverbank trail and the river itself. The exact methods best suited to reach the goals of the project are not fully vetted at this time and will require the assistance of resource professionals, along with discussions among multiple agencies and stakeolders through the Henry’s Fork Watershed Council. Project outcomes along the way could also direct the remaining scope of work.

Current Project Partners: Henry’s Fork Foundation and Harriman State Park

Estimated Cost and Funding Potential: The total project cost is roughly estimated at $143,000. Several grants have been submitted by the Henry’s Fork Foundation to various funding entities, both public and private, to supplement funds acquired through the Foundation’s Campaign for Wild Trout. Harriman State Park has placed the project on the CIN (Capital Improvement Needs) list, and subsequently the project has made the Idaho Department of Parks and Recreation (IDPR) Statewide Priority List, Maintenance Needs, for FY 2017. Placement on the Priority List does not guarantee funding.

Tentative timeline (pending project funding):

August-October 2015: Contract with an engineering firm to establish a full scope of work for the project.

October 2015: Present the project to the Henry’s Fork Watershed Council for a Watershed Integrity and Review Endorsement (W.I.R.E.)

2016 and 2017: Complete necessary construction projects.