Discussion leaders: Brent Yarnal and Zoe Johnson

Notes by Rob Neff

• Surprise: we have more planning for drought management than for high flow events.
• Some planning for ice jam flooding; also a forecasting system, national weather service, etc., for timely flood forecasts and warning.
• Regional climate change projections: more rainfall, more flood frequency, yet more severe droughts. We have seen more and deeper droughts in past 10 years, but not sure if this is from CC.
• If we have more intense droughts, planners will need to adjust.
• Water quantity has become more of a planning issue in recent years; prior focus was on quality.
• Surprise: VA uses more water
• This is function of low population combined with high industrial use
• Some may be from electricity generated in VA but used elsewhere …. how do you attribute this? They’re not really using this water.
• Surprise: higher precipitation apparently won’t be offset by evapotranspiration.

• How might changes in water temperature affect water treatment, algal blooms?
• These haven’t been given much thought, but changes in temperature have affected water treatment in other places.
• Temperature is related to DO, thus ecosystems.
• Would like to see historical use patterns, and projections
• USGS has not made a full time series available; they may have it, but it will take time to dig it up.
• We need to relate water to time, temp, climate (wet v dry); e.g., high temp = high usage, usually also during low flows.
• ACE has modeling back 20 years or so.
• Are there studies of relationships between regions, such as MARA and NYC?
• E.g., NYC has control over Catskills. Efforts to get NYC to reduce per capita consumption seem to be having an impact. There might be pressure to adjust existing interstate compacts under CC.
• One of the biggest users is COMED to produce electricity. They use high-quality municipal water. Attempts to get them to use gray water have been largely unsuccessful.
• Might relate water use directly to population. SRBC has projected water demand and supply to 2020, but need to recognize that demand is outside as well as inside the water basins. Water use in the lower part of the basin is increasing drastically.
• Groundwater supplies … what about acid mine drainage? Not mentioned in report.
• Acid mine drainage is primarily a local concern, rather than regional.
• In some areas, this is a big problem. But, we had time and space constraints.
• Should we stop dredging the Delaware River because changes could bring in more saltwater? Can model sea-level rise; could have a big impact on some intakes.
• We’ve already seen some Salt water intrusion because of drought; e.g., Raratan. Could this get worse if sea level rises?
• Links between coastal and fresh water: More ground water withdrawals means more ground compaction and higher vulnerability to sea level rise?
• Could we see more sedimentation/erosion? Deforestation increased sedimentation, but trend has slowed or reversed due to reforestation. More work could be done on this, partly because all sediments are not created equal.
• Impacts of timing or rain combined with temperature: for instance, rain-on-ground results in higher erosion than rain-on-snow
• This is a critical link; statistical model includes temperature as well as precipitation. Also need to put our water balance model to more use.
• Forests group work shows it is dangerous to extend models out to the next 100 years. Human impacts are unlikely to be the same in 100 years
• Didn’t see any socio economic analysis … there have been some studies that relate precipitation to runoff, then to impacts on specific urban settings …
• Profound that even the large water systems have a planning horizon of 5 years or less
• Smaller systems, are part-time, mostly moonlighters …. and that’s 95% of the water managers in the SRB.
• Editorial comment: There is no "Clean Drinking Water Act;" use SWDA or CWA.
• What if these projections are wrong? with less water, we could be in serious trouble.

• Gives impression that changes would be gradual and linear. Mention surprises, potential for nonlinearities and extreme events. Do we need to plan for such eventualities?
• More attention to the socio economic impacts, and relationships to "where people live."
• More graphics, and a thinner report. Now have to read the whole section to glean the important issues. Ultimately, this goes to stakeholders, who don’t know the issues but want to know what they need to do.
• Boil down some of the information, and do some of the up-front digesting.