Wetlands: when construction stops monitoring starts

By PATRICIA PLUMB
David Evans and Associates

Goals and performance standards are established for wetland mitigation plans during the agency approval process. Many agencies require a wetland construction bond -- based on the value of a project's wetland -- to ensure that mitigation projects will be installed. Release of the bonds will only occur after compliance of the permitted wetland plans.

A critical component to secure the release of the bonds is mitigation monitoring. The calendar for monitoring should start at the end of construction when approvals have been secured.

A mitigation monitoring program is conducted to evaluate the performance standards and assess the success of the mitigation plan in achieving the goals of the mitigation. The time period involved typically ranges from three to five years. The actual monitoring period is defined by each city and county in its sensitive or critical areas ordinance, or in some cases by state or federal regulatory agencies.

The five elements that are the basis of wetland mitigation monitoring are vegetation, hydrology, water quality, wildlife observations and photographic documentation.

Vegetation

Vegetation monitoring is performed on an annual or bi-annual calendar. Visits may be scheduled in the early growing season, May to June, or in the August to September late season. Specific parameters evaluated are plant cover, tree and shrub survival, and plant vigor and vitality. These parameters are used to measure plant species establishment over time.

Development of site transects and/or quadrants, replicate sampling and random observation are techniques used to measure and monitor vegetation conditions.

Hydrology

Wetland hydrology monitoring verifies water regimes and determines hydroperidocity. Seasonal sampling is initiated on a quarterly basis for the first year. Monitoring occurs on a semi-annual basis for the successive years.

Wetlands typically are monitored for three to five years, assessing wildlife, water quality, vegetation and hydrology.

Four critical periods in the first year are the recharge period in November to December, maximum runoff period of January to February, plant utilization months of May to June, and finally minimum hydrology level of August.

Crest gauges, staff gauges and ultrasonic transducers and chart recorders are the typical tools used. Monitoring will occur at control structures, at location of the greatest depth, as well as permanent transect end-points.

Water quality

Water quality monitoring is often only required if the wetland will receive water from water treatment and/or detention facilities to determine if storm water may have an affect on the wetlands. Measurements often are made simultaneously with vegetation and hydrologic monitoring but may also be performed immediately after large storm events or at routine intervals when measuring hydrology.

Structures such as nest boxes, snags, downed logs and loafing areas are observed to see if they are used by wildlife.

A variety of locations will be used for measurement such as storm water inlets, outlets and key positions identified on site. Measurements usually are made for temperature, turbidity, fecal coliform, total phosphorus, total nitrogen, TSS conductivitiy and pH.

Measurements for metals such as zinc, copper and lead are performed in addition to organics testing such as oil/grease, pesticides/herbicides and polynuclear aromatic hydrocarbons (PAH) may also be required if these substances pose a potential hazard to sensitive areas.

Wildlife

Performed on a quarterly basis, wildlife monitoring determines what type and species of wildlife uses the wetland mitigation habitat. Permanent locations are identified for wildlife observation stations. These locations may be situated in the open for long distant viewing, or behind a screen for close up observation.

A sampling procedure is established for observation consistency including the time of day and duration. Wildlife structures installed during the construction phase are observed for wildlife use to assess functional value. The structures in typical use are nest boxes, snags, downed logs and loafing areas.

Measurements will be direct observation and signs of wildlife presence. Species of particular interest are any threatened, endangered or sensitive species; game species; and amphibians.

Photographs

Photographic documentation is the final element in a complete mitigation monitoring plan. The purpose is to establish a permanent record of the overall appearance and revegetation establishment.

Photo documentation occurs on a semi-annual basis, usually in conjunction with vegetation sampling. Permanent locations will be established, including at an off-site location to provide a panoramic view of the project.

Successful monitoring is based on sequential and overlapping frames, photo alignment with previous years photo images, and compass-bearing coordinates to ensure exact locations.

Annual monitoring reports are prepared for submittal to the regulatory agencies. This documentation is key to the ultimate release of project bonds.

Copyright © 1998 Seattle Daily Journal of Commerce.