"Golf borrows water" ... More than 50% of the water used on modern irrigation systems percolates into the ground and adds to the area's groundwater resources. This is especially important in regions where recycled water is used on courses because that water (un-drinkable) is then filtered when it percolates. The golf course, in that case, is taking treated sewage water and returning it to the ground where it can replenish water that has been extracted. The plant (turf) and soils act as filters. Some water used for irrigation evaporates and some trans-evaporates through the plant (turf) leaves. While those "losses" may seem unproductive, they do serve the environment through cooling and that moisture (water) does not leave planet earth — it remains in the atmosphere and eventually becomes precipitation.
I hope that helps. BTW, this came up when I attended a Western Governor's Conference several years ago and listened to a scientist talk on the ski industry's use of water to make snow. It was fascinating to hear how water (both recycled and fresh) was used during the winter and then melted in the Spring along with natural snow.
Another factor is to consider where "golf water" comes from. For example, if the water comes from a surface flow (river or lake) then you must consider the evaporation factor of that source. When "borrowing" that water, a golf course is taking a certain volume, preventing a portion of evaporation, using the water and then immediately returning a percentage to the ground and allowing plants (turf) to carry out photosynthesis. A typical 18-hole golf course produces enough oxygen for about 7,000 people.