Benefits of Retention Ponds: Tour of Sheridan Nurseries
The CFFO Water Stewardship Task Team went for a tour of Sheridan Nurseries’ Georgetown campus last week to see the innovative water irrigation system and retention pond that Sheridan has installed. We were treated to a tour by Bart Brusse, the Container Manager, and Pieter Joubert, Vice President of Nursery Operations.
Retention ponds have many benefits, including the peace of mind knowing that there is enough water to bridge the gap in a dry year, and allowing for greater recovery and reuse of water in an irrigation system. If predictions are correct, in the future we may get far more instances of significant rain in one large storm event, followed by a dry period. Well managed ponds and irrigation, be that for nursery plants as here, or for crops and pasture, mean that producers can be reliable sources for their customers, and can be resilient in dry conditions.
Our tour began with fields of potted plants. Most of the Sheridan’s sales comprise plants in containers which are too small for drip irrigation. These are watered every morning with overhead sprinklers. Plants in 5 gallon pots or larger can be watered with a more elaborate hosed spray/drip method, delivering water directly to each pot. This method uses 70% less water than the overhead sprinklers, although the equipment can be harder to orchestrate and maintain. Finally the third method of irrigation has a long tube of drip irrigation laid underground into the same trench with the plants growing directly in the ground.
Through careful design of the beds and fields, excess water from all of these forms of irrigation runs into ditches and is then collected via an elaborate drainage system (including drain outlets that would look more at home on a suburban street). This feeds into a settling pond at the lowest point on the farm, and recovers about 30% of the water used. Water slowly makes its way from the settling pond through a designed wetland, further cleaning the water before it is pumped 4 m up into the large reservoir pond built right next to the wetland.
Although some nurseries truck water in to ensure they have enough, Sheridan is looking for methods to “live within their means.” They are constantly working to improve the efficiency of their water use and recapture methods, and on improving the quality of the water they recover. Sheridan has to acquire permits to take water from the Credit River, its only source of water. Having the reservoir pond ensures that Sheridan can maintain irrigation for at least two and a half weeks should the river level be too low to take water.
2016 is already shaping up to be a dry summer. Sheridan measures the water levels carefully every day. At the time of the tour, the Credit River was about 48% lower than it was at the same time last year. Below a certain river level, their permit to take water requires that their daily limit is reduced by half, and they must stop taking water altogether at a critically low level. They have had seven low-flow days in the past 10 years, hitting the “stop taking water” level in 2012. Days like those are a reminder that the investment in the retention pond system better prepares Sheridan for water uncertainty now and in the future.