US Army Corps of Engineers
Albuquerque District

Colorado Stream Quantification Tool (CSQT)

The Colorado Stream Quantification Tool (CSQT) is a stream condition assessment that is based on the Stream Functions Pyramid. The CSQT was developed as a result of a multi-agency collaborative effort led by the Corps and EPA for the purpose of establishing an objective, measureable, and repeatable method to calculate debits and credits for stream impacts and mitigation in accordance with the approved Colorado Mitigation Procedures (COMP).

The CSQT scores streams within the five basic parameters of hydrology, hydraulics, geomorphology, chemistry, and biology using a combination of metrics that are based on watershed data and common survey and field measurements, such as width-depth ratios, bank erosion, etc. The CSQT combines pre- and post-construction stream lengths with the values from applicable metrics, as determined by a watershed catchment assessment and other site-specific criteria, to produce existing and proposed condition scores that are expressed in functional feet units. The difference between pre- and post-construction conditions (i.e., the delta) is basis for calculating credits (i.e., mitigation sites) and debits (i.e., impact sites) for permitted activities under Section 404 of the Clean Water Act.

The metrics and measurement methods should be familiar to experienced stream restoration and design professionals since they are commonly used by other existing functional/condition assessment methods across the country.

The CSQT is composed of a spreadsheet tool, a user manual, and a scientific support document. All of these documents are available on the Stream Mechanics website at https://stream-mechanics.com/stream-functions-pyramid-framework/.

During the public notice comment period between May and October 2019, the Corps hosted a number of workshops on the CSQT and the COMP. Presentations from the workshops are provided below for those who are interested but may not have been able to attend one of these workshops. Please note, these presentations are intended to provide examples and offer perspective as an aid in understanding of the CSQT and its intended use within the 404 permitting program. The presentations do not constitute agency policy or procedures:

PRESENTATION 1 of 4: Colorado Mitigation Procedures (COMP)

PRESENTATION 2 of 4: Colorado Stream Quantification Tool (CSQT)

PRESENTATION 3 of 4: Functional Loss (Debit Example)

PRESENTATION 4 of 4: Functional Lift (Credit Example)

For additional information about the CSQT and the COMP, please contact Joshua G. Carpenter at (719) 543-9459 x9402 or joshua.g.carpenter@usace.army.mil.