00:25:07 Lamar Williams: Has anyone attributed a portion of the nutrients in the Chesapeake Bay to the Susquehanna's runoff from the farms in Pennsylvania? In particular all the sediment behind the Conowingo Dam? 00:27:34 Amanda Pollack: Lamar - yes there is a separate Watershed Implementation Plan for the Conowingo Dam that accounts for the Susquehanna watershed and is separate from the PA, MD and NY WIPs. 00:27:57 Camille Calure: Can you expand on the meaning of "overburdened community"? Thank you. 00:28:57 Bill Tollner: I had a similar question regarding "overburdened communities." 00:29:11 Bill Tollner: What do you mean by 8 digit watersheds? 00:30:30 Kathy Stecker: MD 8-digit watersheds are not the standard 8-digit HUCs. https://mde.maryland.gov/programs/water/tmdl/datacenter/pages/8digitwatershed.aspx 00:30:52 Charles Hegberg: What if the tree removal is part of forest health or sustainable forest management? 00:31:57 Brianna Martin: I assume the "10 digit watershed" means the HUC ten. More info here: https://nas.er.usgs.gov/hucs.aspx 00:34:03 Beth Uhler: We appreciate everyone's questions (keep them coming!) and will do our best to address them in the discussion portion of the webinar after all presentations have concluded. Also, thanks to those chiming in and providing answers in the chat in the interim! 00:35:38 Lamar Williams: The problem with the MS4 permit, is that it only mandates a reduction of only 20% of the existing impervious area. when are we going to do 50% or better yet 100%? 00:36:48 Heather Barrett: Will the questions and the answers in the chat be sent around? I am just starting to learn about stormwater 00:38:28 Lisa Fraley-McNeal: Yes, we'll send out the chat log after the webinar. 00:39:57 Heather Barrett: Thank you! 00:42:52 Jason Baer: MS4 does not mandate reducing impervious surface, though that is an option. It allows you to "treat" it. The current 20% CBR requirement is a burden for many. Fortunately we are currently in the mid 30s for our treatment and are looking to boost it up into the 40s through a couple of key upcoming projects. We've found that stream restorations give the best bang for the buck. 00:45:46 s schwartz: In this flow-duration-frequency table, what would you consider to be the "channel forming discharge"? 00:48:08 Beth Uhler: The MS4 requirement referenced above is specific to Maryland, for those from other jurisdictions in attendance. 00:48:21 Lamar Williams: Correction, I misspoke. the 20% reduction is to treat the runoff from only 20% of the existing impervious area. Regardless of the semantics, a large of the existing impervious area is not being reduced, treated if you will 00:48:32 Bishwodeep Adhikari: Can you please elaborate on how you defined the "individual rainfall event"? Did you use any specific number of hours to differentiate as individual and separate rainfall events? 00:48:48 John Watson: Well, the higher flow rate occurs during the shorter duration storms, but the higher volumes come the 24-hr storms. Would you like to weigh in on the conveyance vs storage approach to stormwater management and green stormwater infrastructure? 00:49:05 Doug Hokuf: It looks like the pre-developed land cover was primarily agriculture. If modeled (TR-55) as agricultural row crops, the runoff from the developed condition likely improved, even before SWM is incorporated. 00:50:18 Bill Tollner: The fact that the short duration storms produce more runoff than a similar depth over 24 hrs shows me that, when using the curve number to predict runoff, the Curve number is higher for short duration storms than for longer duration storms. This debate is going on within an ASCE committee that is discussing revisions to the NRCS National Engineering Handbook hydrology section. 00:51:40 Bill Tollner: Tess, this is really great information! 00:54:07 Lamar Williams: We need to be more aggressive with regards to managing the stormwater, and treating all of the runoff not just some 00:55:34 Harshad Patel: Remember, the channel erosion is a natural process 00:56:38 Bill Tollner: Is the concept of "Reference Stream" as promulgated by Rosgen strictly valid? It seems like a useful approximation, but we should not press it too far. Any thoughts on this? 00:58:36 Julie Bell: Could you explain the MDE mix? 00:59:17 Erik Michelsen: Harshad, the geological research in this region points to these valley systems having been remarkably stable from the last ice age to the de-forestation period associated with European arrival. 01:00:19 Lamar Williams: LOL! Harshad! But channel has accelerated due to all of the unmanaged stormwater and untreated runoff dumped into our streams. Honestly, the only way to slow down the erosion is to remove all the impervious area that exists, don't drive vehicles, and live the same way the indigenous people did for 40,000 years. If we are not going to do that, then we must be more aggressive with the runoff that is accelerated the channel erosion, not just 20% of the existing impervious area. 01:03:05 Lamar Williams: Correction Harshad, But channel (erosion) has accelerated due to all of the...……. 01:05:13 Harshad Patel: What I meant that despite having best BMPS in place, the stream will experience the stress and cause some erosion issues along the corridor as we continue to develop the watershed 01:05:38 Melinda Daniels: The focus on stormwater infrastructure only designed to "treat" low magnitude (10yr and smaller) events entirely fails to address the powerful and increasingly frequent large magnitude events that effect most of the channel erosion. I'm encouraged to hear that ASCE is considering altering the Curve numbers to reflect storm intensity, but the stormwater design/regulation community also needs to evolve to address larger events. 01:08:43 Bill Tollner: What is the maintenance plan for the sand filters? 01:08:48 Doug Hokuf: This stream eroded when the forest was removed for agricultural. The runoff from the current developed condition would have actually improved this condition. If we really want to streams to be stable , a forest land cover condition must be the pre-developed benchmark used when designing SWM. 01:11:10 Jason Papacosma: Could one good gully-washer undo it all, given channel incision? 01:13:37 Dave Hampton: Byron, can you switch to presenter mode? 01:13:46 Julie Bell: I'm not seeing the slides advancing... 01:14:12 Cidney Jones: Hi Doug, When you say runoff from the developed condition is an improvement from the agricultural land cover, are you focusing on nutrient & sediment loading? 01:15:11 AIleen Winquist: He needs to do slide show first 01:15:21 Gloria Charland: Maybe click “start slide show”? 01:15:28 Mary Larson: display settings on lower right let's you switch to slide show view 01:15:58 Jason Baer: Lamar - you say "erosion" likes it's a dirty word. Erosion is a totally natural process. The "untouched" world of the indigenous people that you suggested we return to was formed, in fact, by erosion. 01:16:43 Peter Carney: Don't treat your soil like dirt! 01:17:18 Dave Hampton: 👍 01:19:34 Lamar Williams: Touché Jason, but we can't make jest of the indigenous people's respect for the environment during their 40,000 year tenure. The Europeans destroyed the environment in less than 400years! 01:20:00 Doug Hokuf: Cidney, I'm referring to runoff (TR-55). The CN for Row Crop, Good Condition, HSG B is 78. The CN for 1/4-acre lots, Good Condition, HSG B is 75, thus producing less runoff. Then if you take into consideration the open space areas (CN 61) required for communities, the overall runoff reduces even further. 01:21:01 Tess Thompson: Meadow is not a row crop. Corn is a row crop. 01:23:34 Lamar Williams: Question all, how do we deal with significant erosion along a streambank? Do we agree with just using riprap and fabric underneath the riprap, or would we prefer to use a geotechnical method of compaction, bridging into the slope, and a combination of riprap, imbricated brick wall installation after the slopes that have eroded have been stabilized and compacted with the oversight of a geotechnical engineer? 01:23:42 Rosalie Starvish: Can design drawings be shared for the sand filters? 01:23:43 Doug Hokuf: Tess, agreed! My comment during your excellent presentation was that it appears from the aerial picture you provided that the predeveloped condition looked like agricultural. Unfortunately, most SW Regulations use the current land use as the design target, only perpetuating the failing condition of the stream. 01:26:15 Kimberly MacPhee: another benefit of the sand filters is that stormwater runoff temperatures are reduced? seems like a no-brainer assumption but just wanted to verify. In our neck of the woods we have coldwater fisheries resources that could benefit from the sand filter approach 01:26:41 Heather Barrett: Same here so please confirm if they do in fact reduce the water temp. 01:30:00 Kimberly MacPhee: This is excellent research and information! Thank you! Are there plans to investigate how other variables like legacy sediments affect stream channel responses to stormwater runoff? We have many watersheds still adjusting to damming, berming, channel straightening, deforestation, etc. Our watersheds are not highly impervious but our streams are unstable due to historic and current land uses 01:30:19 Jason Baer: Let's not forget groundwater recharge. Most folks are focused on treating runoff before getting it into the surface water bodies. Many of our aquifers in Maryland are slowly dying due to over appropriation. We really need to focus on groundwater recharge as a viable method of water treatment. Impervious surface disrupts the hydrologic cycle, which in turn results in the impacts we're discussing today. 01:30:34 Heather Barrett: We have a lot of checkdams of various sizes and materials that we are slowly taking out. 01:33:25 Jordan Fox: Re: Temperature impacts -- I can't speak to any specifics for Carroll County, but the CBP STAC published resources in January 2022 about stream temperature impacts and management responses. Elements 7 and 8 (found at the following link) summarize the impacts of various BMP and restoration projects on water temperature. https://www.chesapeake.org/stac/events/day-1-rising-watershed-and-bay-water-temperatures-e2-80-94ecological-implications-and-management-responses-a-proactive-programmatic-cbp-stac-workshop/ 01:33:57 Heather Barrett: Thank you! 01:34:25 Julie Bell: I'm interested in the restoration of wildlife habitat as part of these projects - It's one thing to improve water quality and reduce peak flows, but are you getting any fish, amphibians, etc. moving to these areas, is it being studied? 01:34:27 Lamar Williams: Anne Arundel has always been ahead of the game with regards to LID. I personally had the pleasure of forming a friendship with Michael Clar who facilitated writing Anne Arundel's 1st LID manual. 01:34:35 Jason Baer: Tess - your presentation was excellent. I'd be interested to hear more about the relationship you observed between storm intensity, duration, peak flow, and the associated in-stream impacts. 01:35:07 Heather Barrett: Is the build up of pollutants an issue in these areas? 01:36:02 Byron Madigan: We've done temperature monitoring at the maintenance center sand filter that I shared last fall at MWMC and will be sharing that data again in July with the Chesapeake Stormwater Network. 01:36:27 Melinda Daniels: It's great to see the extensive use of large wood in these projects. 01:38:32 Gloria Charland: Takeaways from the meeting 👉💬 [ ] Finalize and share the research paper on the impacts of development and stormwater regulations on stream channel stability. (Tess Thompson) [ ] Continue post-treatment monitoring through August 2026 and prepare the final report by December 2026. (Lisa Eby) [ ] Monthly photo documentation of stream reaches from April through October as part of the long-term monitoring. (Byron Madigan) See full summary - https://otter.ai/u/dyPC2hCLr_Qn5pp3GkK7-iGpIG0?utm_source=va_chat&utm_content=wrapup_v4&tab=chat&message=2f354b6f-1ad7-47cc-b49d-3fbeb44e3ab7 01:46:48 Beth Uhler: Please enter questions in the chat. 01:49:30 Dave Hampton: Dave w/ LimnoTech, Byron and Erik: what have been the top barriers to innovations in BMP 01:49:55 Dave Hampton: Implementation barriers for county govts 01:50:34 Jared Freddo: How did you address budget/ funding in a shared Ms4 Permit? Did downstream township/county pay for upstream projects? 01:54:56 Jared Freddo: When introducing a sand filter retrofit, were the downstream eroded barestream banks (seeded, planted or live staked with native shrubs as a riparian buffer) or was the growth natural? 01:55:10 Peter Carney: How are you accounting for long-term maintenance & capital replacement costs? 01:58:26 Kimberly MacPhee: I was curious if the designs for SCM that treat higher intensity storms for channel stability would possibly need to be tweaked to accommodate the channel instabilities caused by the damming, berming, etc. 01:59:27 Kimberly MacPhee: In other words, can the models account for this and then the designs are modified accordingly? 01:59:55 Emily Burgess: How would climate change influence metrics of monitoring stream force over time? It seems like it would be impossible to match existing conditions depending on which years you're comparing 02:01:30 Meilifan Parandoush: thank you for such an informative presentations 02:02:02 Bill Tollner: Is there a stormwater management fee that is assessed to residents to generate the maintenance funds. If not, how do you fund the maintenance? 02:02:39 Bill Tollner: Kudos to all for the informative presentations! 02:02:44 Erik Michelsen: Bill, in Anne Arundel County, yes there is. It's around $90 per home per year 02:02:55 Meilifan Parandoush: thank you for such an informative presentations 02:02:58 Erik Michelsen: It's based on actual impervious cover for businesses 02:04:50 Kimberly MacPhee: Thanks Tess and Erik! That is helpful info for a whole watershed approach :) 02:07:06 Jared Freddo: Is source water for Agro and industrial part of MS4 goals? Possibly choosing the source water from surface to ground water based when it would benefit the area. Pull from surface basin when filled? And Recharge ground water when needed? 02:09:25 Lusha, stormwater data, she/her: In king county it is also based on impervious cover (half a dozen percentile classes) for commercial, but it’s flat ~200-300 for residential parcels. There are also discounts for maintenance, mining/grading etc - which I personally think are costly, inequitable and do not recommend. 02:10:35 Charles Smith: Byron and Lisa, what is the limit of analysis for the channel healing below the sandfilter? Are you seeing any trends in what lengths you could expect to affect? 02:11:09 Erik Michelsen: Lusha, we have three categories of residential fees, and all non-residential are billed on measured imperviousness. 02:12:02 Jared Freddo: Thank you 02:12:07 Maha Issa: Thank you for the insightful information and great presentations. 02:12:17 Maya Craig: thanks! 02:12:17 David Waltz: Thanks!@