Alaska Interior Stream Quantification Tool

The Stream Quantification Tool developed specifically for Interior Alaska provides a way to quantify changes in stream condition and be able to compare streams in similar settings.

The Stream Quantification Tool (SQT) is a spreadsheet that calculates change in stream condition associated with stream restoration or impact activities. Functional improvement is calculated for stream restoration and mitigation projects and functional loss is calculated for permitted stream impacts. A debit calculator is included as a separate spreadsheet to assist permitted impactors in making functional loss calculations in the absence of long-term monitoring.

How does the SQT Work?

The SQT converts scores from a variety of assessment methods into a standard index score ranging from 0.0 to 1.0. A zero score represents no function for a given metric and a 1.0 represents a culturally unaltered condition. The assessment methods are typically quantitative and field based. The tool architecture is flexible, so each state or SQT developer can add assessment methods that best fit their region’s needs. A tool has recently been developed specific to non-glacial streams in Interior Alaska.

Assessment methods quantify stream functions in each of five functional categories: hydrology, hydraulics, geomorphology, physicochemical, and biology. Stream scoring includes a condition score and a functional-foot score. The overall stream condition score is a weighted sum of the scores from the five functional categories. The functional-foot score multiplies the condition score times the stream length. The stream is scored for the pre- and post-activity condition. The post condition and functional-foot scores are subtracted from the pre-activity scores to quantify the overall functional change and show improvement or loss.

For example, assessment methods that measure channel depth and floodplain width quantify how connected a stream is to its historic floodplain. These assessment methods are within the hydraulic functional category and contribute to the overall condition score of the stream. Assessment methods looking at the abundance and diversity of aquatic insect populations are typically included in the biology functional category.

The National Park Service will use the Alaska Interior SQT as part of a three-year project to evaluate the current condition and restoration potential of historically mined streams in Denali National Park and Preserve, Wrangell-St. Elias National Park and Preserve, and Yukon-Charley Rivers National Preserve. This information will then be used to prioritize stream restoration projects in these three parks.

What States are Using the SQT?

The SQT is used to show functional improvement and loss as part of compensatory stream mitigation programs in Tennessee, Georgia, Wyoming, Colorado, and Minnesota. It has recently been customized for non-glacial streams in Interior Alaska. And it is being regionalized in Michigan and scheduled to be regionalized in South Carolina. Practitioners in NC and other states use the SQT to assist in site selection/prioritization and to show the functional benefits of stream restoration activities.

Where Can I get More Information?

SQT spreadsheets, field forms, user manuals, and science documents are available on the Stream Mechanics web page. A Function-based Framework for Stream Assessment and Restoration Projects can also be downloaded from the web page. This document provides the conceptual model and framework that was used to develop the SQT.