1. Tackling Algae March 2015 update

2. Agenda Background Our algae working group Raw water management –Catchment –Algae management plans –Reservoir mixing Detection & analysis –Algae monitors –Sampling programme & rapid detection At the WTW - trigger levels and treatment Next focus areas

3. Background Two water quality events in 2014 –Cloughbottom & Denton Water Treatment Works (WTW) Increase in ‘earthy/musty’ taste and odour customer contacts Increase in taste and odour ‘fails’ at the customer’s tap Climate change - WRc report January 2013 –“…Climate change is likely to lead to increased algal growth ….” –“…Cyanobacteria grow better at higher temperatures … the predicted warmer world of the late 21st century will be more suitable for these algae” –“There is also some evidence that climate change could increase nutrient loading to lakes”

4. Our algae working group Prevent - control - detect - treat Objectives: To reduce ‘unwanted’ customer contacts due to taste and odour To eliminate associated category 3 water quality events To reduce the cost of treatment to remove algal taste and odour compounds To avoid impacts of increased solids loading and prolonged WTW shut down Our algae strategy: A twin track approach for interventions with prevention/treatment on the catchment and in reservoirs as well as at the WTW

5. Prevention & Control Catchment Pro-active interventions to prevent algal blooms Nutrient reduction Replace septic tanks Cover manure heaps Fix leaking mains & sewers Nutrient & manure planning advice Prevent stock access to watercourses Buffer strips Animal housing

6. Algae management plans 42 Site specific plans in place Actions to be taken on catchment, reservoirs and at the WTW to prevent algae growth, or to control it when it does occur Reservoir actions include: –Source selection –Mixing –Scour –Variable depth draw off –Compensation flows & overflows to increase turnover Roles & responsibilities clarified

7. Reservoir mixing Prevents ‘ideal’ conditions for algae growth: ‘Resmix’ Existing bubble barriers

8. Detection & analysis Algae monitors Hand held & on-line monitors –trend monitoring & source selection –will be used to develop site specific trigger levels Installing on-line monitors high risk sites & Safeguard zones

9. Detection & analysis Sampling programme & rapid detection Risk assessment of all sites completed 2015 sampling programme agreed –25% increase from 2014, based on risk –Final water analysis where PAC or GAC in use –Algsys instrument based on fluorometry Raw smell and final taste and smell procedure re-launched in November and in use at all sites

10. At the WTW - trigger levels & treatment Currently regional trigger levels Algae trigger levels revised early February –Introduced blue green algae pigment trigger Rapid notification if trigger levels reached GAC installed at 10 of our WTWs Three additional mobile PAC rigs ordered –enabling works and delivery plans being developed for at risk sites –will treat up to 20Ml/d

11. Our next focus areas Cost and scope the most beneficial innovative solutions to pursue Woodland policy and wildlife management under review Further benchmarking meeting with other water companies & CEH Grow our understanding of all factors & complex data Biology –Benthic vs planktonic –Actinomycetes etc