Christmas lights are very pretty and bring joy for the moments they are looked upon, but for the majority of the many hours they are on they go on unwatched, unappreciated. They are on at night, so likely, they are being powered by some form of fossil fuel. Sprinklers while wasted don't leave the water cycle.
Power at night is essentially free for the power company. The % of power used is so low, that is why pay-by-time areas like CA offer it for so cheap. You cannot just turn down the output of these huge turbines. They need to provide power for peak usage, plus overhead. Some places with natural gas burners can run their main plants at below peak but above average plus overhead. Then spin up the natural gas right before peak times to cover that load. But at night time, the average daily usage rate is still being made. That's why this "free" energy is used to pump water back upstream (big hydraulic battery) or charge batteries or in this case power Christmas lights almost nobody sees. Sprinklers in the rain use clean, processed fresh water and dump it onto the ground even though it is already getting clean fresh water. I've lived in a drought for over a decade, and it makes a big difference. Having spent some time on a 3rd world country island nation (Trinidad, of Trinidad and Tobago), water and power are resources you don't take lightly. You have rain barrels and what you collect, you can use. Sure you can take an extra long shower, but then you have nothing to drink. You can plug in everything you own at once, but the main power panel will explode and then you will have no power for weeks until the repair comes out.
Is water fungible? Wasted water in California won't affect the water in those drought stricken areas, right? The price of hydrocarbons on the other hand are globally linked in one fashion or another.
Water is more regional. But wasted water in Las Vegas effects me in Colorado. Our utility sells our mountain water to Vegas for a high price because they are in the desert. Vegas has higher demands then us, so we are second tier even though we get to ski on it before it travels hundreds of miles. I agree that lowering power demands are good globally. However, power plants with the current grid and current infrastructure cannot do that at night time. Another reason I like the newer nuclear designs. They can ramp up and down in minutes, not hours. The coal factory that makes most of the power if it spun down its turbine at night, wouldn't even get it all the way down before it had to start spinning it back up again to get it to output for peak demands in the morning. And spinning up and down uses a lot of energy too. Keeping a flat output with overhead is the best, which unfortunately means lots of otherwise wasted energy at night time. The only forseeable solution is to provide more fast spike peak plants so the big plants can run lower output, or reduce average and peak consumption which have almost nothing to do with night time usage.
we have our Christmas lites on a few hours a night for a few weeks and a rain shutoff device on our sprinklers. both use fossil fuel and are (for now) choices made by each consumer.
It depends. Some places have abundant local water, others import water by desecrating important far-away environments. Some places need to maintain river flow rates in hydro facilities or nuclear base loads at night, others burn coal. Some Christmas lights are just a string or two of efficient LEDs, others are massive displays of incandescent C9s.
Outdoor Xmas lights are bad in this sense- at least lights if burned inside the house, in the winter you get the heat back for heating the house up. Therefore the most eco-ethical is window Xmas or Hanukkah candle lights inside the house.
The problem with all run off water is, it's all for the fish. We get nothing in return, and must survive on our toilet water. If even 50% of the street water was recycled we would have no water shortage problems. While I'm a great nature lover we cannot depend on the natural water cycle so fish may have to take 2nd place. And with increasing human population fish will get edged out, not ideal, but a eventual fact. Either that street runoff water can be cleaned up and reused by us, or keep dumping in the rivers to poison the fish....which is it? The humane choice is to clean up the water First before dumping in the rivers for the fish! As for lights the utility company loves these people, love Las Vegas and Times Square TOO. Now if that water cannot be cleaned up, as they say...... then neither can oil spills in the ocean! Which is it?
Even this varies greatly by locality. Some regions grab and pipe their municipal water from high in the mountains, use it just once, then fast track the treated effluent and runoff quickly to the ocean. Others pull it from the nearest rivers, then put the cleaned up water back into the rivers to be be sent to the next intake downstream, and used repeatedly on its leisurely journey to the ocean.