by Bill Goosman, CDOT, Environmental Progras, Denver

Roads — whether new construction, expansion of existing facilities, or maintenance — have impacts on the environment. Starting with this issue, a series of articles will examine the laws, regulations, and procedures at CDOT that influence wetlands and streams in Colorado, and the challenges the department faces in protecting these resources. Topics will include wetlands, streams and, in the context of those resources, water quality, revegetation and weed management, and threatened and endangered species.

As development continues, impacts to streams and riparian areas increase while areas for potential mitigation too often decrease.

CDOT and Wetlands
Presidential Executive Order 11990, Protection of Wetlands, was signed by President Jimmy Carter in 1977 and provides the framework for wetland-related activities at CDOT. It requires all federal agencies to avoid and minimize impacts to the nation’s wetlands, whether those impacts are direct or result in the indirect degradation of wetlands. The executive order underpins the many of the wetland-related regulations and practices in Section 404 of the Clean Water Act as well as those followed by the Federal Highway Administration (FHWA). Section 404 is administered by the U.S. Army Corps of Engineers (COE) and governs dredge and fill operations in the nation’s waterways (“waters of the United States”), including wetlands. In terms of FHWA, much of what CDOT does — and how it does it — is governed by the laws and regulations of FHWA as well as agreements that CDOT has with FHWA regarding implementation of those laws and regulations.
The most effective place to “avoid and minimize” resource impacts is at the planning and project scoping stages of project development. These activities are overseen by the region planning and environmental manager in each of CDOT’s six regions. In general, as the need for a project is identified, these managers and their staff work closely with project managers, design engineers, and headquarters staff to identify natural resources in the project area or corridor, identify alternatives and potential impacts to those resources, and discuss ways to avoid or minimize those impacts. For example, road alignments can be moved slightly to completely avoid an existing wetland or roadway side slopes can be steepened (within safety limits) so that the overall “footprint” of the road is not as wide and impacts lessened.
According to the laws and regulations, every “practicable” effort must be expended toward avoidance and minimization. “Practicable” is defined as “available and capable of being done after taking into consideration cost, existing technology, and logistics, in light of overall project purposes.” After all efforts have been expended, the remaining impacts to wetlands are considered unavoidable. COE monitors wetland impacts through its nationwide and individual permit system while FHWA monitors such activities through required wetland “findings.”
For private parties contemplating projects that will impact wetlands, mitigation of impacts may or may not be required depending on whether the impacted wetlands fall under the COE’s regulatory purview, i.e., “are jurisdictional,” and whether the extent of those impacts exceed the thresholds of the various permits in the Section 404 program. For CDOT, the situation is different.

As a bridge reaches the end of its design life, it is scheduled for replacement. Wider, safer structures often mean impacts to adjacent riparian areas that have grown close over time. CDOT procedures require consideration and mitigation of those impacts.

All impacts to wetlands for CDOT projects must be mitigated — the size of the impact does not matter, nor does it matter whether the wetlands are jurisdictional or non-jurisdictional. (Examples of non-jurisdictional wetlands include irrigation ditches and roadside drainage ditches.) Federal policy and practice often requires 1.5-to-1 or greater replacement of wetlands or greater. This is intended to offset potential failures of mitigation as well as an acknowledgement that not all wetlands are fully protected and not all wetland impacts must be mitigated. The constraints of Colorado water law and the difficulties and costs involved with acquiring water rights impose unique constraints on CDOT. In exchange for COE and FHWA recognizing the difficulties that these conditions pose for mitigating wetland impacts in Colorado, the department agreed to mitigate for all wetland impacts, both jurisdictional and not, and the department’s replacement ratio would be 1-to-1. Statewide, those impacts totaled 6.3 acres during 2001.
The recent U.S. Supreme Court case known by the acronym SWANCC (Solid Waste Agency of Northern Cook County vs. U.S. Army Corps of Engineers) effectively took away Corps jurisdiction of “isolated wetlands,” most simply defined as those wetlands not directly connected to or adjacent to rivers, streams, and their tributaries. As a result, such areas are now considered non-jurisdictional. For many entities, this removed the need to mitigate for impacts to such isolated wetlands. Again, this is not the case with CDOT — as noted above, the department mitigates for impacts to all wetlands. Recent federal court cases have issued differing interpretations of the Clean Water Act post-SWANCC, thus issues surrounding regulatory oversight of wetlands continue to evolve.
Once all practicable effort has been expended to avoid and minimize impacts to wetlands, remaining impacts must be mitigated. The prospects of mitigation usually means that additional time will be required to identify appropriate mitigation sites or to gather additional information about those sites. This means that such possibilities must be considered early in the project process. For instance, for sites within CDOT right of way, groundwater hydrology wells may need to be installed and monitored to determine if adequate water is available and what sort of excavation or site contouring may be needed. Similarly, stream runoff data may be needed to insure proper design of in-stream structures and related stream restoration efforts. If sites within existing CDOT right-of-way are not adequate (e.g., too small) or are inappropriate (e.g., insufficient water, too costly), additional time and resource may be necessary to identify and purchase private parcels adjacent to the project or to find similar parcels held by other natural resource agencies, whether local, state, or federal. Additional issues related to mitigation on CDOT projects will be discussed in more depth in the next article.
CDOT and the Riparian Environment
Impacts to riparian wetlands may be governed by Section 404 or FHWA rules and requirements, or they may be governed by a Colorado state law, Senate Bill 40 (SB 40; 33-5-101, et seq., C.R.S., 1973). Many local, state and federal laws govern water use and water quality degradation, fish and wildlife, land use, and wetlands, but SB 40 is somewhat unique in that it attempts to address potential impacts to each of these aspects of stream health by protecting the stream ecosystem as a whole.
SB 40 requires any state agency to obtain certification from the Colorado Division of Wildlife (CDOW) when the state agency plans construction in any stream, its banks, or tributaries. Emphasis in this legislation is on the protection of fishing waters in the state, but it also recognizes the importance of protecting the entire stream ecosystem, including wetlands and riparian areas. These provisions also apply to local agencies using state funds for similar purposes.
In 1990, CDOT and CDOW signed an agreement intended to streamline the SB 40 certification process for transportation projects. Under this agreement, the provisions of SB 40 extend to: 1) perennial streams, 2) segments of intermittent streams providing live water beneficial to fish and wildlife, 3) segments of streams supporting 25 percent or more cover of riparian vegetation within 100 yards upstream and downstream of a project, and 4) segments of streams having wetlands present within 200 yards upstream or downstream of the project. Construction and maintenance in intermittent drainages may also be covered, even when no water is present in the drainage. Jurisdiction includes the stream bed proper, the stream’s immediate banks; and as much of the bank side area as could reasonably be expected to contribute to the quality of the general stream habitat, including shading, water quality filtering, and contribution of food items. Based on these criteria, the provisions of SB 40 may extend some distance from the stream itself under some circumstances, although that distance varies with the type and size of the stream and its floodplain.
The agreements established a series of thresholds that, below which, CDOT could proceed with the projects without going through the formal certification process. This is based on the assumption that most CDOT projects involve only minimal disturbance to streams, especially if CDOT adheres to a set of best management practices (BMPs) during construction. Projects with impacts in excess of the thresholds require formal certification from CDOW. As with wetlands, potential stream-related issues should be identified early in the project scoping process, so that early comments and suggestions can be incorporated in project plans.
For CDOT projects, the agreement sets forth 12 criteria that, if any one of which is met, mean the project requires formal certification. The most commonly used criteria are listed below.

  1. Permanent fill of stream-associated wetlands greater than ¼ acre.
  2. Temporary fill of stream-associated wetlands greater than ½ acre.
  3. Total permanent and temporary impacts to wetlands greater than 1.0 acre.
  4. Permanent or temporary stream re-alignment greater than 100 feet for a fishing water or 200 feet for a non-fishing water.

In exchange for this expedited certification process, CDOT has agreed to practice a variety of BMPs in and near streams that are intended to avoid or minimize negative impacts from the projects. Some of the conditions and practices are listed below. The following conditions and practices are ultimately specified in the project plans, including any required mitigation:

  1. Clean, non-soil fill must be used for coffer dams and temporary road crossings.
  2. Discharge into streams from coffer dams and other diversions, and from dewatering and washout areas is prohibited.
  3. Proper erosion control and stormwater management practices must be observed.
  4. Disturbance to existing vegetation must be kept to a minimum. Revegetation must occur as quickly as possible after disturbance, and re-seeding should employ appropriate native species. Also, as much of streamside vegetation rootstock should be left in place.
  5. Construction staging areas must be located well away from streams and adjacent areas.
  6. Where possible, stream flows should be diverted around (rather than through) construction sites in order to keep materials out of the water.
  7. In-stream construction must be conducted during low-water periods and resulting structures should not unduly constrict stream flows.
  8. In certain streams, in-stream work is restricted to times of the years when fish are not migrating or spawning.

In addition to these general conditions, there are special conditions that apply to specific types of projects, including structural crossings, bank stabilization, stream encroachments, and channel re-alignments. For example, for structural crossings and stream realignments, the stream’s profile, substrate and habitat values should be returned to pre-construction conditions, or better. For bank stabilization, work should be performed from above the stream when possible, rather than in the stream.
Continuing Challenges
On a day-to-day basis, the activities and decisions of CDOT personnel at all levels — policy makers, project managers, designers, and maintenance — have the potential to impact various natural resources. To help department employees to understand those impacts, CDOT environmental staff conducts on-going formal and informal educational efforts. These include seminars on which resources are protected and why and, perhaps more importantly, staff provides advice on proper field practices, such as for erosion control and water quality, avoidance of impacts to habitats of threatened species, and wetland or stream protection practices. These efforts also occur daily through informal interactions between CDOT environmental staff and project management, during design, construction, and during the myriad maintenance activities that follow.

Snake River just upstream of Dillon Reservoir.
Imaginative combinations of engineering and mitigation can address several problems. The bendway weirs on this project retrained the river, removed threats to bridge abutments, stopped erosion to the hillside, and provided areas for wetland mitigation.

As space becomes an issue for people in Colorado, so too is space becoming an issue for CDOT as it attempts to mitigate wetland and stream impacts. Although there are few completely new state highways being built, many existing roads are being expanded in size. When obsolete structures are replaced or existing roads are reconstructed, they must be brought up to current safety standards. This usually means that they will be wider and cause more impacts.
In the case of unavoidable wetland and stream impacts, CDOT first tries to replace the resource as close as possible to the site of impact. U.S. Army Corps of Engineers’ (COE) regulations increasingly view mitigation in terms of functional replacement and what is best for the aquatic resource, including a watershed perspective. Thus, there is some movement away from strictly requiring one-to-one replacement of wetlands. For example, although impacts may have occurred to wetlands, the area may be better served by re-establishing riparian vegetation along a degraded section of stream. In this way the functions and values of the resource are retained locally. Impacts on CDOT projects often involve sites previously impacted by the original road or bridge. CDOT can, therefore, address mitigation by restoring previous damage and upgrading the resource in the vicinity of the project. This might include placement of in-stream boulders to improve fish habitat or re-seating a drainage pipe or box culvert to improve the low flow channel to add fish passage. Nevertheless, good sites for wetland mitigation, such as larger, consolidated areas, are becoming increasingly scarce and increasingly expensive, especially if water rights are involved. Mitigation banks and in-lieu fee arrangements provide additional alternatives.
Recent reconstruction of a portion of State Highway 6 in Summit County illustrates that construction projects can provide unique opportunities to address several problems. Wetland impacts on the project resulted from widening of the road into wetlands on either side. Additional concerns identified the meandering of the Snake River into an erosive shale bluff. As the river bend continued to eat into the base of the bluff, water flows increasingly threatened the abutment of the bridge where the river empties into Dillon Reservoir. To solve both problems, the river flows were realigned by several bendway weirs installed at the base of the bluff. The spaces between the weirs were filled with topsoil salvaged from the wetlands impacted by the project. Additional plugs of wetland plants along with willow cuttings were harvested locally and installed. Hydrology wells, stream runoff data, and adjacent reference wetlands were used to set the elevation of the site. Nearly all the plugs and willow cuttings survived, although the short growing season at altitude will slow coverage of the site. In normal precipitation years, this wetland should be saturated or inundated for six to eight weeks in the spring.
Under state water law, wetlands are viewed in essentially the same way as cropland, that is, they reflect a certain amount of water use. If wetlands are destroyed on a CDOT project, usually the same size wetland may only be re-established downstream of the impact. This eliminates any net impact on the amount of water available in the drainage. Because a re-created wetland essentially means moving water from one place to another, the mitigation wetland may be re-established upstream only if there are no intervening diversions or water right holders. For the same reason, wetland mitigation is seldom moved to a wholly different drainage. Either situation would likely involve the need to purchase water rights to support the relocated wetland. In order to avoid such expenses, CDOT strives hard to keep mitigation for wetland and stream impacts local.
Adjacent landowners and land uses may also influence CDOT’s mitigation options. For instance, if the state highway or interstate is located in a National Forest on US government property, the District Ranger may have policies and procedures requiring certain mitigation sites and strategies. These aspects keep constant pressure on CDOT to find sites at which to mitigate project impacts, but they can also provide opportunities.
A CDOT project along US Highway 285 west of Bailey impacted wetlands along the South/North Fork of the South Platte. The existing corridor is narrow and most appropriate areas for additional wetlands were either not for sale or already contained wetlands. Discussions followed with the USFS and an area along Hoosier Creek, a tributary to the south/north fork near to top of Kenosha Pass, was identified. A wetland in this area had been severely impacted by routing of the railroad and the placement of several feet of ash from a coke operation active during the late-1800s. CDOT worked with the Forest Service to design a plan to remove the layers of ash and to raise the water level to pre-disturbance levels. The area responded almost immediately and is today providing exceptional habitat for many different species. Fortunately, recent changes in COE 404 permit conditions have increased CDOT’s flexibility in terms of the types of mitigation that are possible.
One difficult aspect of highway projects is longer-term funding of their environmental components. Although most projects end in the fall, project contracts are often left open to the following spring to finish planting and seeding under better growing conditions. The living component of a highway project can be more fickle and unpredictable than the concrete and guardrails, and the success of the living component may not occur for some time, even years later. For instance, COE permit conditions may require several years of monitoring of a wetland mitigation site. Additional funds may be needed to adjust site elevations, to fix hydrologic or hydraulic features, to replace trees and bushes, and for weed management. On multi-year, multi-phase projects, finding the money is usually less of an issue, but on one-time projects, funding for backhoe work or for a dozen additional erosion control logs can be truly a hat-in-hand effort.
CDOT environmental personnel have a wide variety of laws, regulations, and interests to keep in mind — the need to avoid and minimize resource impacts, the need to mitigate for unavoidable impacts to wetlands and streams, the need to protect water rights, the need to maintain a safe transportation systems, and to use tax dollars sanely. Much time and effort is spent reconciling the inevitable conflicts between these various responsibilities and establishing a practical balance among them.

Colorado Riparian Association