Published: April 24, 2024 By

Currently, there are two conflicting bills in the Colorado Legislature that would create a new state program regulating the dredge and fill of wetlands and streams across the State – HB 24-1379 and SB 24-127. A key question facing lawmakers is the scope of this new program or, in other words, which wetlands and streams will be protected. The sponsors of the Senate Bill assert that it will mirror the federal program as it existed under the Obama Administration and that it adopts the “significant nexus” test, which dictated the scope of the federal Clean Water Act program during that timeframe. This article dispels that argument and demonstrates that SB24-127 would, in fact, cover far fewer wetlands and waterbodies than were protected under the significant nexus test of the federal Clean Water Act.

I. The “Significant Nexus” Test

The history of wetland regulation at the federal level has a long and complicated history that we have previously detailed. The Supreme Court has now decided four cases that address the definition of “Waters of the United States” (WOTUS). In response to those cases, nearly every administration since 2000 has attempted to craft its own definition of WOTUS by regulation.

In 2006, the Supreme Court decided Rapanos v. Army Corps of Engineers, and Justice Kennedy developed by the significant nexus test in his concurring opinion.1 Pursuant to this test, wetlands were said to have a significant nexus to traditional navigable waters if, “either alone or in combination with similarly situated lands in the region, significantly affect the chemical, physical, and biological integrity of other covered waters.”2 To conform with this test, the Obama administration amended the regulatory definition of WOTUS and included eight categories of waters.

Under this regulatory definition of the significant nexus test, any wetlands located within the 100-year floodplain and are not more than 1500 feet from the ordinary high-water line were defined as “adjacent” and therefore a WOTUS.3 Additionally, wetlands within 4,000 feet of the high-water mark of any traditional navigable water, interstate water, territorial seas, impoundments, or covered tributaries could be included as a WOTUS if they have an effect on the chemical, physical, or biological integrity of navigable waters.4 Therefore, the significant nexus set a floor by including all wetlands within the 100-year floodplain and within 1500 feet from the ordinary high-water line while also protecting certain other wetlands within 4,000 feet of a high water mark depending on site characteristics.

II. Distinguishing SB24-127 from the Significant Nexus Test

SB24-127 does not fill the gap created by Sackett, because it does not provide potential protections for those wetlands out to 4000 feet from the ordinary high-water mark, which could include a significant number of wetlands in a high elevation state like Colorado. SB24-127 would limit the jurisdiction of the new state removal fill program, to those waters within the 100-year floodplain and those not more than 1500 feet from a lake, reservoir, or stream.5 Unlike the Obama Administration’s significant nexus test, however, SB24-127 does not provide for coverage for any wetlands outside the 100-year floodplain and 1500-foot demarcation, regardless of whether those waters have a significant nexus to traditional navigable waters. Thus, if a wetland were outside the 100-year floodplain and 1501 feet away from a state water, it would not be protected regardless of how important that wetland may be in protecting the integrity of state waters and wildlife habitat.

SB24-127 claims to limit jurisdiction under these parameters because it would help remove the time intensive and costly process of completing case-specific analysis to determine jurisdiction. However, the program will still have to engage in determining which wetlands are subject to the state agency’s jurisdiction.

III. Implications for Colorado

Our analysis demonstrates that SB24-127 does not fill the gap created by the Sackett decision. As compared to the significant nexus test that was put in place by the Obama Administration after the Rapanos decision, SB24-127 would protect far fewer wetlands across Colorado even though these wetlands play a critical role in protecting clean water, wildlife habitat, and outdoor recreation.

In our view, HB24-1379 is the better policy choice, because it includes all wetlands within the definition of state waters and thus does not require time-consuming and expensive case-by-case determinations about jurisdiction. HB 24-1379 also includes exclusions for certain activities – not categories of wetlands – which are much easier to administer. And it relies heavily on general permits for routine categories of activities, which provide predictability and certainty for the regulated community.

If we make the wrong policy choice in designing Colorado’s wetland protection program, we may possibly threaten the interconnectedness of our water systems in Colorado, create long-term water quality impacts, and affect downstream waters. Our state waters also play a vital role in flood and fire mitigation which are likely to be of greater importance as climate change ravages the Western United States.

SB24-179 does not fill the Sackett gap, it instead creates new, unpredictable regulatory gaps that will be difficult and expensive to administer, creating uncertainty for the regulated community and other stakeholders. If there is one thing we have learned from the tortured history of the federal wetland program it is this – any attempt to define the scope of the program based on the “connection” between a wetland and other surface water is doomed to conflict and unnecessary expense. All wetlands deserve protection, especially here in the state of Colorado. We have an opportunity right now to avoid that morass, but SB24-179 would simply lead us back down that same dusty road.


1 547 U.S. 715 (2006).

2 Id. at 780.

3 33 C.F.R § 328.3 (2018).

4 Id.