The Alaska Stream Quantification Tool: Scoring the Health of Historically Mined Streams

The Stream Quantification Tool developed for Interior Alaska measures changes in stream condition and allows comparison of streams in similar settings. Image from the National Park Service's page.

The Stream Quantification Tool (SQT) is a spreadsheet that calculates how much a stream's condition changes with restoration or with damage. For restoration and mitigation projects it calculates functional improvement; for permitted impacts to streams, functional loss. A separate debit calculator helps those with permits estimate losses when there is no long-term monitoring.

How it works

The SQT converts scores from a range of assessment methods — usually quantitative and done in the field — into a standard index from 0.0 to 1.0: 0 means no function for a given measure, 1.0 a culturally unaltered condition. The tool is flexible, so each state or developer can add the assessment methods that suit the region.

• Five functional categories: hydrology, hydraulics, geomorphology, physicochemical and biology. For example, measures of channel depth and floodplain width show how connected a stream is to its historic floodplain (hydraulics); counts of the abundance and variety of aquatic insects usually fall under biology.
• Two scores. The condition score is a weighted sum of the five categories' scores. The functional-foot score multiplies the condition score by the length of stream.
• Before and after. The stream is scored before and after an activity; subtracting one from the other gives the overall change, improvement or loss.

In Alaska's parks

A version was recently developed for non-glacial streams in Interior Alaska. The National Park Service will use it in a three-year project to assess 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, and then to prioritise restoration projects in the three parks.

Where else it is used

• Compensatory stream mitigation programmes use the SQT to show functional improvement and loss in Tennessee, Georgia, Wyoming, Colorado and Minnesota.
• Being adapted for Michigan, with South Carolina scheduled.
• Practitioners in North Carolina and other states use it to choose and prioritise sites and to show the benefits of restoration.

The SQT spreadsheets, field forms, manuals and supporting science — and A Function-based Framework for Stream Assessment and Restoration Projects, the conceptual model behind the tool — are available from the Stream Mechanics website.

Sources

• National Park Service, "Alaska Interior Stream Quantification Tool." https://www.nps.gov/articles/000/aksqt.htm
• Rewritten in hubnx's own words.