Purpose: The purpose of the Instream Flow Methods Conference was to achieve agreement among the invited experts on the most appropriate method(s) for estimating an accurate relation between streamflow and fish habitat quantity and quality in Water Resources Inventory Area No.1 (WRIA 1).

Participants: Conference participants can be categorized into two groups: 1) a Technical Team comprised of experts in the various scientific disciplines related to instream flow, and 2) interested parties associated with the WRIA 1 Watershed Management Project. Dr. Thomas Hardy of Utah State University was unanimously selected by the WRIA 1 Staff Team and Administrative Decision-Makers of the five Initiating Governments to be the General Chairperson for the conference.

The Staff Team, Dr. Hardy, and the Planning Unit selected and invited 29 instream flow experts from the public and private sector to be members of the Technical Team (see Attachment 1). Due to scheduling conflicts and/or time constraints, only 12 of the invited experts were able to participate for all or most of the conference. Although all of the invited experts could not participate on the Technical Team, Dr. Hardy felt confident that the 12 participants represent a broad cross-section of perspectives on the best way to estimate the relation between streamflow and fish habitat quantity and quality. As will be described later, some of the invited guest who could not participate during the conference agreed to be part of an independent peer review panel of the conference technical report. The 12 members of the Technical Team that participated in the conference and their affiliations are identified in Table 1.

Interested parties associated with the WRIA 1 Watershed Management Project supported the Technical Team by answering questions about the availability of information or other aspects of the WRIA 1 Watershed Management Project. In addition, the interested parties met informally with the experts during breaks and lunch. Interested parties who participated in the conference for at least one full day and their affiliations are identified in Table 2. The entire proceedings were professionally recorded and video-taped for parties who could not attend the conference due to scheduling conflicts and/or time constraints.

Conference Products: Dr. Hardy has agreed to develop a conference technical report that will serve as the technical foundation for the strategic workplan for assessing instream flow needs throughout WRIA 1. The conference report will be based on the formal and informal discussions that occurred between the experts during the conference and the scientific literature related to assessing instream flow needs. Dr. Hardy will provide the WRIA 1 Watershed Management Project with a copy of all of the reports and journal articles cited in the conference report.

The revised delivery schedule for the final conference report and intermediate working drafts is presented in Table 3. As shown in Table 3, the conference report development effort will include four review cycles with the final report delivery scheduled for March 3, 2000. The four review cycles will be comprised of: 1) review by conference participants, 2) review by Initiating Governments and Planning Unit, 3) review by independent panel of experts, and 4) general public review. After the comment period for each review draft, Dr. Hardy will incorporate comments as appropriate. A comment form will be developed to ensure that comments are focused on the report contents. Dr. Hardy has offered to make a presentation to the general public on the report contents at the start of a public review period on January 21, 2000.

Conference Summary: Attachment 2 is the Agenda for the Instream Flow Methods Conference. After introductions and a presentation of the conference ground rules and objectives, the conference participants addressed five main topic areas: stratification, hydrology methods, field data collection methods, habitat modeling, and habitat suitability criteria/indices. The discussion related to each of these topic areas is summarized below.

Conference Objectives: Initial discussion focused on identifying the streamflow level that the WRIA 1 Watershed Management Project was trying to estimate. As shown in Figure 1, instream flow levels needed to preserve, protect, and restore the physical, biological, and chemical aspects of water can be divided into five functional categories: 1) water quality maintenance, 2) fisheries baseflow, 3) channel maintenance, 4) riparian maintenance, and 5) valley maintenance. Each of these flows components were identified by the Technical Team as essential for maintaining the ecological health of the stream system.

Briefly, the water quality maintenance flow is the quantity of water needed to assimilate wastewater and still achieve compliance with applicable water quality standards. The fish habitat maintenance flow is the minimum instream flow needed to support fish populations during different life stages. Technical Team members noted that a 1993 Washington State Supreme Court case identified the minimum instream flow as the optimum instream flow (quantified using appropriate methods). The channel maintenance flow is the minimum amount of water needed to perform processes such as sediment transport. The channel maintenance flows impact the long-term characteristics of aquatic habitat such as the quantity and quality of pools and riffles. Riparian maintenance flows are the flows needed to maintain a productive plant and animal community along the stream corridor. Valley forming flows are catastrophic flood events and are generally not quantified.

Stratification: If there were no budget or time constraints, appropriate field data needed to quantify ecologically based flow regimes of stream segments could be collected at all points of interest throughout WRIA 1. Pragmatically, the cost and time associated with field data collection and analysis efforts prohibits such an approach in the short-term. To balance cost and time constraints with the needed level of accuracy, the Technical Team concurred that some form of basin stratification will be required.

Stratification of the basin means that the entire study area will be subdivided into groups of self-similar watersheds/subbasins. The Technical Team identified a wide range of parameters that should be used to define self-similar subbasins and generally agreed that the three primary parameters to use when stratifying the study area are 1) longitudinal slope, 2) geology, and 3) hydrology.

The Technical Team indicated that the stratification results could be analyzed and validated by determining if there is less variability within strata than throughout the study area. Also, the stratification based on the physical attributes of the subbasins could be compared with the distribution of fish/biological attributes of the subbasins to validate the parameters used to stratify the study area.

Hydrology Methods: The Technical Team discussed what hydrologic information is needed to evaluate instream flow at any point in the study area. The Technical Team agreed that in general, the more high quality hydrologic data that can be collected for the area, the more accurate the resulting estimates of the five flow components identified as essential for maintaining the ecological health of the stream system. The hydrologic study being conducted by the U.S. Geological Survey in the basin should, at a minimum, develop all of the 31 flow statistics identified by Richter et al. (1996).

Hydrologic relations are used to estimate the five flow components and are often used to develop interim estimates of the fish habitat flow component. The interim fish habitat flow estimates are then refined using more complex methods as time and budget allow. In WRIA 1, because Washington State has already estimated instream flow needs for fish habitat as part of the Instream Resource Protection Program (IRPP), the Technical Team agreed that there is no need to develop or identify interim instream flow needs. The focus should be on conducting Instream Flow Incremental Methodology (IFIM) approaches within each stratum to validate the existing estimates.

Field Data Collection Methods: The Technical Team noted that there is a wide variety of stream types to be sampled in the study area and that the most appropriate field data collection methods depend on the stream type and the approach used to estimate the ecological flow regime. Identified stream types in the study area include estuaries, well-confined (single) mainstem channel, multi-channel (braided) mainstem channel, low gradient single and multi-channel tributaries, and small high gradient streams. Field data collection efforts should generally include:

• mapping habitat and channel form;
• identifying when and which life stages of various species occur (periodicity);
• channel cross-section geometry;
• channel longitudinal geometry;
• channel substrate and cover;
• flow velocity and depth;
• water quality (e.g., temperature, dissolved oxygen, sediment, nutrients, metals); and
• benthic invertebrates.

The complexity of the channel and habitat affects the data collection needs. In general, more data need to be collected to accurately characterize complex channels and habitats than to accurately characterize uniform channels and habitat types. As an example, five or six cross sections may be needed to characterize a complex mesohabitat whereas only two cross sections may be needed to characterize a uniform mesohabitat.

The Technical Team was in general agreement that hydroacoustic mapping coupled with the simultaneous collection of cross section data is the best method for big rivers. Following a discussion of the variety of methods that exist in the literature for estuaries and high gradient streams, it was agreed that Dr. Hardy would detail methods and considerations in the conference report.

Habitat Modeling: In general, the Technical Team agreed that habitat modeling should not focus on only one fish species and that the importance of invertebrates in the system needs to be addressed. The Rapid Biological Assessment (RBA) approach was identified as a starting point for considering invertebrates. Methods used as part of the National Water Quality Assessment (NAWQA) program were also identified as a possible framework for considering invertebrates. The Physical Habitat Simulation (PHABSIM) element of the Instream Flow Incremental Methodology (IFIM) and two-dimensional modeling were identified as the best available physical habitat modeling approaches. It was noted that even though the channel shifts over time, which results in changes in the location of habitat, the estimated instream flow needs should be about the same for a given stream reach. Additionally, caution was expressed that the results of all models need to be field verified and validated. The habitat modeling results could be validated using methods such as spawner surveys, smolt traps, and snorkeling surveys.

Habitat Suitability Criteria/Indices: Habitat suitability indices (HSIs) are an analytical tool used to represent preferences that different fish species have for various instream conditions/variables (e.g., velocity, depth, cover) at different life stages. In general, the indices are curves ranging from 0 to 1 for the particular habitat variable with 0 meaning no preference for the particular habitat condition and 1 meaning high preference for the particular condition. There was discussion about how HSI curves may have been misused in the past by adopting regional curves rather than developing HSI curves specific to a stream or stream system. It was noted that field observations suggest the HSI curves for a species may change within a 10-mile reach. As a result, the WRIA 1 Watershed Management Project could expect to have different HSI curves for the North Fork and South Fork of the Nooksack River.

The Technical Team agreed that HSI curves should be based on preference not "usability" because a species may prefer a particular habitat but may not be observed using the preferred habitat simply because the preferred habitat does not exist or is not available. The Technical Team unanimously recommended that a HSI workshop be convened to develop interim HSI curves for the study area and also to identify the process that will be used to develop and test the interim curves. The field data collection effort for the WRIA 1 Watershed Management Project should be integrated to allow for the testing and developing of HSI curves for the study area.

Summary: The Instream Flow Methods conference was a success in that a representative group of experts in instream flow quantification/estimation methods came to general agreement on the most appropriate method(s) for estimating an accurate relation between streamflow and fish habitat quantity and quality in WRIA 1. Dr. Hardy did an excellent job working with the conference participants to ensure that the wide range of viewpoints was expressed on the different issues. The conference technical report that will be finalized by March 3, 2000 will provide a technically sound, peer-reviewed workplan that will identify an integrated assessment framework for estimating the flows necessary to maintain the ecological health of the stream systems in WRIA 1.

Richter, B.D., J.V. Baumgartner, J. Powell, and D.P. Braun. 1996. A method for