Drought and Your Wetland Mitigation Site

Over the summer of 2001 irrigation, maintenance, and supplemental monitoring will be critical in helping your mitigation site survive our unusually dry conditions.  The greater Puget Sound region is experiencing serious drought conditions. 

Traditionally, fall and spring are the best times to install tree, shrub, and emergent plantings within wetland mitigation sites.  However, plants installed last fall and this spring are suffering drought stress on top of the rigors of installation shock.  Despite drought conditions your mitigation site is still required to meet approved performance standards.  What can you do to ensure the success of your wetland mitigation site through ‘the drought?’

IRRIGATION:  Possible water restrictions this summer, may tempt you to allocate water resources elsewhere, but your mitigation site is legally required to succeed, drought or no drought.  Performance standards require that plants not only survive, but increase in size and cover.  To do that, they must have regular bi-weekly, deep watering.  The upland buffers surrounding your wetland areas also need irrigation, particularly if they were planted with salal or sword fern.

MULCH:  In addition to water, mulch is a plant’s best friend.  Mulching helps keep roots cool, helps the soil around your plants retain water, and helps deter competition from weeds.

WEED OUT INVASIVES:  The last thing a drought stressed plant needs is competition from an aggressive neighbor.  Blackberry, Scot’s broom, reed canarygrass, thistle, and mullein frequently invade mitigation sites and compete with plantings for scarce resources.  Hand-removal of these species at their first occurrence and subsequent hand-application of approved herbicide will help prevent their spread on your site.  This is an on-going maintenance issue that will need to be repeated at least yearly.  Many mitigation plans specify a maximum of not more than 10 to 15 percent cover by invasive species.

This summer promises to be challenging for everyone and your mitigation site is no exception.  Care and maintenance is the best protection of your investment of time and money.  Replanting and the potential for extensions of your long-term monitoring period make this essential.

Raedeke Associates, Inc. can help you assess the health of your mitigation site, correct problems promptly, and conduct both required and supplemental monitoring to help ensure the success of the site and timely release of your bond.

If you have questions about wetland mitigation sites, please contact Chris Wright at Raedeke Associates, Inc. at (206) 525-8122 or email him at  cwright@raedeke.com.