US Army Corps of Engineers BUILDING STRONG ® 2012 Changes to Stream Mitigation Procedures and Guidelines Mike Moxey USACE, Mobile District IRT Chair May 10, 2012

BUILDING STRONG ® Draft 2012 Mobile District Stream SOP  Addresses Perennial, Intermittent and Ephemeral Streams 1. Field Identification Method 2. Functional Assessment 3. Commensurate Mitigation Strategy in Worksheets

BUILDING STRONG ® Stream Types  Perennial Stream - A perennial stream has defined bed and bank (channel) features with flowing water year-round during a typical year. The water table is located above the streambed for most of the year. Groundwater is the primary source of water for stream flow. Perennial streams support a diverse aquatic community of organisms year round and are typically the streams that support major fisheries.  Intermittent Stream – An intermittent stream has defined bed and bank (channel) features with seasonal flowing water, when ground water provides water for stream flow. During drier periods, an intermittent stream may not have flowing water. The biological community of an intermittent stream is composed of species that are aquatic during a part of their life history or move to perennial water sources.  Ephemeral Stream – An ephemeral stream bed may or may not have well defined bank (channel) features with flowing stormwater only during and for a short duration after precipitation events in a typical year. The streambed of an ephemeral stream is located above the water table (uplands) year-round and runoff is the primary source of water. Ephemeral streams are upland features that under normal circumstances do not contain aquatic communities. Definitions synthesized from: 1) 2012 Nationwide permits, February 21, 2012 Federal Register and 2) the N.C. Division of Water Quality – Methodology for Identification of Intermittent and Perennial Streams and Their Origins and 3) July 2010 HGM Manual for the Functional Assessment of High-Gradient Ephemeral and Intermittent Headwater Streams in West Virginia and Eastern Kentucky.

BUILDING STRONG ® Intermittent Stream (Obvious?)

BUILDING STRONG ® Ephemeral Stream

BUILDING STRONG ® Stream Identification Protocols in Mobile District

BUILDING STRONG ® Commensurate Mitigation for Ephemeral Streams Less mitigation More mitigation For all streams, riparian buffer effects water temperature with shading and is a source of POC and DOC to downstream aquatic resources. Contribute to functional and ecological integrity of downstream aquatic resources Ephemeral Streams: Dedicated upland collection and delivery system for hydrology, sediment, and organic material supply to downstream system. Intermittent streams also provide aquatic insect (surface and hyporheic zone), aquatic habitat, and fisheries functions when flowing. Perennial streams also provide consistent fisheries, aquatic insect, and aquatic habitat functions. Ephemeral Intermittent Perennial

BUILDING STRONG ® HGM Functions

BUILDING STRONG ® Changes to Mobile District Stream SOP: Existing Condition  A. Geomorphologically Stable (Stable) These streams exhibit reference condition pattern, profile and dimension. The channels show very little incision and little or no evidence of active erosion or unprotected banks (usually outside stream bends only), within the stream reach % of both banks are stable and contain vegetative surface protection or natural rock stability along the majority of the banks. Stable point bars and bankfull benches are present (when appropriate for the stream type). These channels are stable and have access to their original floodplain or fully developed bankfull benches. Correct sediment size and type for the stream type. If sediment deposition is present, it covers less than 10% of the stream bottom and is transient. Ephemeral streams have greater than 75% canopy coverage or a high quality riparian zone habitat.

BUILDING STRONG ® Proposed Changes to Stream SOP Adverse Impact Worksheet

BUILDING STRONG ® Proposed Changes to Stream SOP In-Stream Credit Worksheet

BUILDING STRONG ® Goal for Riparian Buffers

BUILDING STRONG ® Vs. No Riparian Buffers

BUILDING STRONG ® Proposed Changes to Stream SOP Riparian Buffer Calculations

BUILDING STRONG ® Continuing Challenges With Ephemeral Streams  Physical form and functions are dependent upon landform and normal rainfall events. How do we design appropriate projects if these have changed?  What are the criteria for prioritizing on-site versus off-site mitigation?  What is the standards and protocol for evaluating temporal and spatial success of ephemeral stream channel mitigation projects?

BUILDING STRONG ® Any Questions? U.S. Army Corps of Engineers Attention: Mike Moxey 109 St. Joseph Street Mobile, AL Phone: Website: