Glen Canyon Dam Long-Term Experimental 

and Management Plan Supplemental

Environmental Impact Statement 

TWG Meeting, Nov 7, 2023 
 

 

 

 

 

 

 

 

How does the LTEMP SEIS differ from other 

current planning activities? 

PLANNING 

EFFORT 

RANGE OF 

OPERATIONS 

DURATION 

NEAR-TERM 

COLORADO RIVER 

OPERATIONS 

(Interim Guidelines 

SEIS) 

GLEN CANYON DAM 

LONG-TERM 

EXPERIMENTAL AND 

MANAGEMENT PLAN 

(LTEMP SEIS) 

LONG-TERM COLORADO 

RIVER OPERATIONS 

(Post-2026 Process) 

Limited sections of the 

2007 Interim 

Guidelines 

Focus on annual 

releases 

Limited sections of the 

2016 LTEMP ROD; 

Sub-annual flows - timing 

of hourly, daily, monthly 

and experimental releases 

from Glen Canyon Dam 

Revisit all sections of the 

2007 Interim Guidelines 

and other operating 

agreements that expire in 

2026. 

Focus on annual releases 

2024 – 2026 

(3 YEARS) 

2024 – 2027 (Flow 

Alternatives) 

2024 – 2036 (HFE protocol) 

2026 AND BEYOND 
 

 

 

 

 

 

 

 

 

Purpose and Need 

• The purpose of the LTEMP SEIS is for Reclamation to analyze additional flow

options at Glen Canyon Dam in response to invasive smallmouth bass and other

warmwater nonnatives recently detected directly below the dam.

• The need is to prevent the establishment of smallmouth bass below the Glen

Canyon Dam (by preventing additional spawning), which could threaten

populations of threatened humpback chub downstream.

• The LTEMP SEIS will also consider the HFE protocol by including the latest scientific

information to improve Reclamation’s ability to implement HFEs as originally

intended in the LTEMP EIS. Specifically, Reclamation is considering adjusting the

sediment accounting periods and implementation windows.
4 
5 
 

The Invasion Curve from DOI Invasive Species Strategic 

Plan (2021-2025) 

6 – LTEMP SEIS Public Scoping 
 

 

 

 

 

Glen Canyon Dam/Smallmouth Bass Flow Options Draft 

Environmental Assessment (EA) 

• Published February 2023 

• Evaluated operational alternatives at Glen Canyon 

Dam that may serve to disrupt spawning of 

smallmouth bass and other warmwater invasive 

fish that pass through the dam. 

• Nearly 7,000 comments received with many 

comments focused on the effects to hydropower 

generation and revenues as well as the effects on 

Tribal resources. 

• Reclamation concluded that additional analysis 

was warranted. 
Preliminary Alternatives

Four actions analyzed in the Glen Canyon Dam/Smallmouth Bass Flow Options 

Draft Environmental Assessment (February 2023). 
Preliminary Alternatives 

• All action-alternatives will include a revised annual sediment accounting period 

and implementation window associated with the HFE protocol. 
 

 

 

 

Scoping Process 

• Notice of Intent was published in the 

Federal Register on October 4, 2023. 

• 30-day public scoping comment 

period ended November 3, 2023. 

• Public Webinars are held on October 

18 and 20, 2023. 

• Glen Canyon Dam Adaptive Management Program |

Bureau of Reclamation (usbr.gov) 

10 – LTEMP SEIS Public Scoping 
 

 

 

 

 

 

 

LTEMP SEIS: Proposed Schedule 

Reclamation publishes 

NOI to Prepare SEIS -

initiates NEPA Process -

Begins public Scoping 

Period 

October 4, 2023 

Reclamation develops Scoping 

Summary Report with 

anticipated Purpose & Need 

Nov 2023 

Reclamation prepares 

Draft EIS 

Nov - Dec 2023 

Jan 2024 

Publication of Draft SEIS with 

public comment period to follow 

Public Scoping Period – 

opportunity for public to provide 

input on scope of SEIS and Purpose 

and Need for Proposed Action 

Oct 4th – Nov 3rd 2023 

May – Jun 2024 

Publication of Final SEIS and 

Record of Decision issued 

Key NEPA Process milestones – Opportunities for Tribal, State, Partner, Stakeholder, and Public engagement 
Questions