How old is your wetland delineation report?

Posted in: Environmental, Water


So what drives the five-year shelf life of a delineation report of potentially jurisdictional waterbodies? The U.S. Army Corps of Engineers reissuance of nationwide permits every five years is a key factor. Regulatory Guidance Letters regarding approved jurisdictional determinations also mention a five year expiration date.

A delineation report for a jurisdictional stream or wetland is a snapshot in time of definitive, quantifiable, physical features that change in response to dynamic forces, mainly water. For streams, the affected physical features include beds and banks.

The Blue River in Johnston County, Oklahoma, is a perennial stream defined by its seasonal fluctuations in flow. I am familiar with the Blue River and its tributaries due to ongoing projects I’m working on at Oka’ Yanahli Preserve.

In the coming weeks, Mead & Hunt will re-delineate multiple tributaries of the Blue River within a 480-acre area of the approximate 3,500-acre preserve. A delineation of these streams was originally completed in 2012. Now, five years later, it is time to update that assessment due to ongoing work at the site and changes to the streams at Oka’ Yanahli.

As with any perennial stream, the Blue River is subject to seasonal changes in flow rates. Based on data from the U.S. Geological Survey gauge on the Blue River at Connerville (#07332390), since 2012 the river experienced a minimum of 16 flood events where the discharge and/or flow rates exceeded 2,000 cfs. Seven of those flood events exceeded 10,000 cfs. That much water during multiple flood events guarantees changes to the Blue River and its tributaries at Oka’ Yanahli. For comparison, the Blue River’s monthly flow rate mean is 56 cfs for August between 1976 and 2016.

One Blue River tributary is an intermittent stream that had a delineated length of 6,520 linear feet in 2012. During a July 2015 flood, the stream lost about 650 linear feet when the location of its connection (confluence) to the Blue River moved upstream. The initial length of 6,520 linear feet was accounted for in a compensatory mitigation project as part of a Clean Water Act 404 permit. The pending delineation report will document the changes to this stream and the Blue River.

So, if you have an ongoing project involving streams or wetlands have you looked at the date of your related delineation report lately? We can help you update that data and report. Give me a call.

ABOUT THE AUTHOR

Kim Shannon is a member of the environmental leadership team at Mead & Hunt. She has worked on a variety of project types, including oil and gas, electric transmission, nuclear, transportation, commercial development and local government. She is a former President of the Oklahoma Native Plant Society and the current President of the Oxley Nature Center Association in Tulsa. Effusive and friendly, Kim is happiest outdoors with her plants.

Other blog articles by Kim include:

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