Thank you for the opportunity to comment on the October 2022 Preliminary Drafts for the Municipal Stormwater General Permits and Stormwater Management Manuals (SWMMs). The Lower Columbia Fish Recovery Board (LCFRB) is the regional recovery organizati...↓
Climate Change Impacts on Stormwater Management
The proposed new section on climate change impacts to stormwater management is necessary as we continue to experience more severe flooding events in the winter, and lower stream flows in the summer, which further stress salmon and steelhead populations. Table 1-1.1 (Future Hydrologic Projections) notes not just expected changes in rainfall but increased winter streamflow and decreased summer streamflow conditions, with the following draft text acknowledging the importance of hourly rainfall and flashiness information for stormwater management. Maintaining existing and expanding stream gauge stations to provide watershed-specific information is a critical part of successful management responses to climate change. Southwest Washington rivers have limited stream gauge and temperature data today to capture the variability in flow and thermal regimes across stream orders and resulting from development and climate change. Ecology is the state agency best situated to protect and expand this essential data set, and we encourage the department to develop budget proposals that account for streamflow and temperature data needs, which are identified the WRIA 25/26, 27/28, and 29A Watershed Management Plans Expanded monitoring will not only provide more accurate environmental data for stormwater management, but support restoration project design and habitat capacity estimates for recovering salmon and steelhead. This fits well with many of the climate change mitigation recommendations in the preliminary draft, especially maintaining and increasing natural ecosystem areas.
Stormwater Pollutants and Their Adverse Impacts
This section includes a placeholder for pollutants from tires and other rubber products (including 6PPD-q). This new section will improve alignment with stormwater management and salmon and steelhead recovery. In southwest Washington, stormwater permit areas overlap with ESA-listed salmon and steelhead populations in the Lower Cowlitz, Coweeman, North Fork Lewis, East Fork Lewis, Salmon Creek, and Washougal watersheds. Many of these watersheds are rapidly urbanizing. Coho salmon are especially likely to be harmed by stormwater runoff, and important populations are found in all of these watersheds. In fact, the only coho salmon populations that have reduced extinction risks from very high to moderate - low today are found in the Lower Cowlitz, Coweeman, and Salmon Creek watersheds. The Salmon Creek population especially is a success story: originally designated a low priority for recovery because much of the watershed drained developed lands in the City of Vancouver, this population has some of the highest abundances in southwest Washington today. Salmon Creek coho salmon will likely continue to be important to species-scale recovery along with Lower Cowlitz and Coweeman River populations, and additional protections from stormwater are critical to continued success.
Preliminary Draft Fact Sheet: Tree Retention
This fact sheet identifies future permit language updates to identify tree canopy goals to support water quality, and associated reporting by permittees regarding canopy cover status and changes over time. We support tracking and implementing tree canopy coverage goals into stormwater management guidance because of the important habitat and hydrology benefits forests provide salmon and steelhead. The benefits of tree canopy coverage are more expansive than just riparian habitat and hydrology though: mature forests and riparian corridors provide important public health, stormwater, and wildlife resources, especially in light of climate change impacts to streamflow patterns and temperatures. The broader significance of tracking and restoring tree canopy points to the importance of identifying consistent and centralized data sources and reporting efforts beyond just stormwater permittees reporting to Ecology. The LCFRB has struggled to fund and consistently report on riparian and watershed-scale tree canopy coverage because datasets are either too coarse to effectively assess fine-scale riparian conditions (e.g. National Land Cover Database), too expensive to acquire regularly with our relatively small budget (e.g. field measurements as identified in the Lower Columbia Habitat Status and Trends Monitoring program), or incomplete for the full region (e.g. High Resolution Change Detection). This is not a unique struggle, and Ecology has the opportunity to provide important data and reporting to multiple communities across Washington State through its tree retention update.
Canopy coverage reporting should be based on science-based standards for riparian corridor habitat functions. Washington Department of Natural Resources and Washington Department of Fish & Wildlife both provide riparian habitat information based on site potential tree height, a scientific standard for habitat function. Although urban areas typically support more narrow and disconnected riparian areas, starting with site potential tree height defined habitat areas will place habitat functions at the forefront of decision making. This will also expand the benefits of riparian habitat beyond just stormwater management needs, supporting positive public health, wildlife, and salmon recovery outcomes.
We ask that Ecology consider the following when incorporating tree canopy reporting into the updated SWMMs:
•Provide state level land cover data in partnership with other state agencies at fine-scales to support consistent and accurate watershed and riparian-scale reporting; and
•rely on existing science-based standards for riparian habitat definitions (site potential tree height) to support broader ecosystem benefits beyond just stormwater management.
Thank you for the opportunity to provide feedback on this important permit update. Effective stormwater management is a critical component of protecting and restoring salmon and steelhead habitat as southwest Washington urban areas continue to grow and develop and climate change increases the severity of stream flow and temperature regimes. We are excited to continue partnering with Ecology and stormwater permittees to support watershed health and salmon recovery goals in the lower Columbia River. If you have any questions, please feel free to contact me at (360) 425-1553 or via email at smanlow@lcfrb.gen.wa.us.
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